Patent Publication Number: US-2022219309-A1

Title: Power tool with multiple modes of operation and ergonomic handgrip

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. Non-Provisional application Ser. No. 17/456,420, filed on Nov. 24, 2021, and titled “Power Tool With Multiple Modes Of Operation And Ergonomic Handgrip,” and claims the benefit of U.S. Provisional Application No. 63/199,108, filed on Dec. 7, 2020, and titled “Power Tool With Multiple Modes Of Operation And Ergonomic Handgrip,” both of which are incorporated by reference herein in their entireties. 
    
    
     TECHNICAL FIELD 
     This description relates to a power tool with multiple modes of operation and an ergonomic handgrip. 
     BACKGROUND 
     When performing fastening tasks such as fastening sheet goods to interior or exterior walls, there are many variations in the fastening tasks that present challenges to productivity. For example, there are variations in material types and hardness, variations in fastener quality and fastener type, variations in wall type (e.g., wood vs. metal) and wall thickness, as well as other variations. Many power tools for performing fastening tasks, such as screwguns, have one speed and/or one mode for the varied fastening tasks and situations. Having one speed and/or one mode to cover all fastening variations can lead to damaged or broken fasteners, which causes delays and lost productivity. Users may also manually slow the screwgun down using partial trigger actuation, which also reduces productivity and increases user fatigue. 
     Additionally, power tools such as screwguns are a type of “dead spindle” power tool where the motor and the output spindle are separated from each other until the user applies pressure to push the two component together. Once the corresponding clutches engage, power is transmitted from the motor to the output spindle and a fastener (e.g., screw) is driven into a work piece. Generally, these power tools have an on/off trigger that a user needs to pull to drive the fastener. 
     It is desirable to have a power tool for fastening and other tasks, such as a screwgun, with technical improvements that address these challenges. 
     SUMMARY 
     According to one general aspect, a power tool includes a housing, a motor disposed in the housing, a motor controller disposed in the housing and electrically coupled to the motor, a transmission disposed in the housing and coupled to the motor, and a tool bit holder configured to be rotatably driven by the motor via the transmission and configured to receive a tool bit for rotatably driving threaded fasteners. The power tool includes a power switch actuatable from outside the housing and coupled to the motor controller to control power delivery to the motor and an electronic mode select switch actuatable from outside the housing and electrically coupled to the motor controller. The electronic mode select switch is configured to select between at least a first mode of operation in which power delivery to the motor is controlled by actuation of the power switch and an electronic lock on mode in which continuous power is delivered to the motor upon a single actuation and release of the power switch. 
     According to another general aspect, a power tool includes a housing including a motor housing portion, a transmission housing portion coupled to the motor housing portion, and a handle portion coupled to and extending transverse to the motor housing portion, a motor disposed at least partially in the motor housing portion, a motor controller disposed in the housing and electrically coupled to the motor to control power delivery to the motor, a transmission disposed at least partially in the transmission housing portion, and a tool bit holder configured to be rotatably driven by the motor via the transmission and configured to receive a tool bit for rotatably driving threaded fasteners. The power tool includes a power switch actuatable from outside the housing and coupled to the motor controller to control power delivery to the motor and an electronic mode select switch coupled to and actuatable from outside the motor housing. The electronic mode select switch is electrically coupled to the motor controller and is configured to select among a plurality of modes of operation of the motor, where the electronic mode select switch is configured to be actuatable by a user with one hand while gripping the housing with the one hand in a position for actuating the power switch and driving a threaded fastener into a workpiece. 
     According to another general aspect, a power tool includes a housing including a motor housing portion, a transmission housing portion coupled to the motor housing portion, and a handle portion coupled to and extending transverse to a bottom surface of the motor housing portion, where the motor housing portion includes a top surface generally opposite the bottom surface. The power tool includes a motor at least partially disposed in the motor housing portion, a motor controller disposed in the housing and electrically coupled to the motor, a transmission disposed at least partially in the transmission housing portion, a tool bit holder configured to be rotatably driven by the motor via the transmission and configured to receive a tool bit for rotatably driving treaded fasteners, a power switch actuatable from outside the housing and coupled to the motor controller to control power delivery to the motor, and an electronic mode select switch coupled to and actuatable from outside the motor housing portion. The electronic mode select switch is electrically coupled to the motor controller and configured to select among a plurality of modes of operation of the motor. The electronic mode select switch is disposed on the top surface of the motor housing portion. The power tool includes a belt clip disposed on the top surface of the motor housing portion. 
     According to another general aspect, a power tool includes a housing, a motor disposed in the housing, a motor controller disposed in the housing and electrically coupled to the motor, a transmission and clutch assembly disposed in the housing and coupled to the motor, where the transmission and clutch assembly includes at least an output clutch and an input clutch, a tool bit holder configured to be rotatably driven by the motor via the transmission and clutch assembly and configured to receive a tool bit for rotatably driving threaded fasteners, a power switch actuatable from outside the housing and coupled to the motor controller to control power delivery to the motor, an electronic mode select switch actuatable from outside the housing and electrically coupled to the motor controller and having one or more modes of operation for controlling power to the motor, and a mode change sensor for sensing changes in position of the output clutch, where the mode change sensor is located forward of the input clutch and is configured to send signals to the electronic mode select switch responsive to sensing changes in the position of the output clutch. 
     According to another general aspect, a power tool includes a housing, a motor disposed in the housing, a motor controller disposed in the housing and electrically coupled to the motor, and a transmission and clutch assembly disposed in the housing and coupled to the motor. The transmission and clutch assembly includes a planetary gear assembly having a planet carrier, an output clutch, an intermediate clutch coupled to one face of the planet carrier, and an input clutch integrated with an opposite face of the planet carrier. The power tool includes an electronic mode select switch coupled to and actuatable from outside the motor housing, where the electronic mode select switch is electrically coupled to the motor controller and is configured to select among a plurality of modes of operation of the motor, and a tool bit holder configured to be rotatably driven by the motor via the transmission and clutch assembly and configured to receive a tool bit for rotatably driving threaded fasteners. 
     According to another general aspect, a power tool includes a housing, a motor disposed in the housing, a motor controller disposed in the housing and electrically coupled to the motor, a transmission disposed in the housing and configured to be driven by the motor, an output spindle extending from the housing and configured to be moved axially relative to the housing when depressed against a workpiece, a clutch disposed between the transmission and the tool bit holder, the clutch having an input clutch member coupled to the transmission and an output clutch member coupled to the output spindle, the output clutch moveable between a rearward position in which torque is transmitted from the transmission to the output spindle via the clutch when the output spindle is depressed against a workpiece, and a forward position in which torque transmission from the transmission to the output shaft is interrupted, a sensor assembly including a sensed member coupled to the output spindle axially forward of the output clutch member and configured to move axially with the output spindle and a sensing member axially fixed relative to the housing to sense a position of the sensed member, and a brake mechanism configured to engage the output member the clutch when in the forward position to inhibit rotation of the output member, the brake mechanism including at least one leg extending from a point axially forward of the sensed member and extending past at least a portion of the sensed member to engage the output clutch member when in the forward position. 
     The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a front perspective view of an example screwgun. 
         FIG. 1B  is a rear perspective view of the screwgun of  FIG. 1A . 
         FIG. 1C  is a right side view of the screwgun of  FIG. 1A . 
         FIG. 1D  is a front view of the screwgun of  FIG. 1A . 
         FIG. 1E  is a left side view of the screwgun of  FIG. 1A . 
         FIG. 1F  is a rear view of the screwgun of  FIG. 1A . 
         FIG. 1G  is a top view of the screwgun of  FIG. 1A . 
         FIG. 1H  is a bottom view of the screwgun of  FIG. 1A . 
         FIG. 2  is left side cutaway view of an example screwgun. 
         FIG. 3A  is a top rear perspective view of an example screwgun with a removable clip. 
         FIG. 3B  is a top rear perspective view of the screwgun of  FIG. 3A  with an exploded view of the removable clip. 
         FIG. 4  is a partial rear perspective cutaway view of the screwgun of  FIG. 3A . 
         FIG. 5  is a partial top rear perspective view of the screwgun of  FIG. 3A  with the removable clip removed. 
         FIG. 6  is a partial right side cutaway view of the screwgun of  FIG. 3A  with the removable clip removed. 
         FIG. 7  is a side view of a mode change switch from the screwgun of  FIG. 3A . 
         FIG. 8  is a perspective view of the mode change switch of  FIG. 7 . 
         FIG. 9  is an example schematic of an example indicator for a mode change switch. 
         FIG. 10A  is a right side view of a screwgun being gripped in a first position. 
         FIG. 10B  is a left side view of the screwgun of  FIG. 10A  being gripped in the first position. 
         FIG. 10C  is a top view of the screwgun of  FIG. 10A  being gripped in the first position. 
         FIG. 10D  is a top view of the screwgun of  FIG. 10A  being gripped in the first position with the thumb near the mode select switch. 
         FIG. 11A  is a right side view of the screwgun of  FIG. 10A  being gripped in a second position. 
         FIG. 11B  is a left side view of the screwgun of  FIG. 10A  being gripped in the second position. 
         FIG. 12A  is a left side view of the screwgun of  FIG. 1A . 
         FIG. 12B  is a rear view of the screwgun of  FIG. 1A . 
         FIG. 13A  is a rear portion perspective exploded view of an example transmission and clutch assembly for a screwgun. 
         FIG. 13B  is a front portion perspective exploded view of the transmission and clutch assembly of  FIG. 13A . 
         FIG. 13C  is a rear portion perspective exploded view of an example transmission and clutch assembly with a braking mechanism. 
         FIG. 13D  is a perspective view of the braking mechanism of  FIG. 13C . 
         FIG. 13E  is a side view of the assembled transmission and clutch assembly of  FIG. 13C  with the braking mechanism engaged. 
         FIG. 13F  is a side view of the assembled transmission and clutch assembly of  FIG. 13C  with the braking mechanism disengaged. 
         FIG. 13G  is a side view of the assembled transmission and clutch assembly of  FIG. 13C  with the braking mechanism engaged. 
         FIG. 13H  is a side view of the assembled transmission and clutch assembly of  FIG. 13G  in a partial cutaway of the gear and clutch case. 
         FIG. 13I  is a side view of the assembled transmission and clutch assembly of  FIG. 13G  in a partial cutaway of the gear and clutch case. 
         FIG. 13J  is a top view of the gear and clutch case of  FIG. 13I . 
         FIG. 14  is a side view of an assembled transmission and clutch assembly for a screwgun. 
         FIG. 15  is a perspective view of an example integrated clutch input face. 
         FIG. 16A  is a rear perspective exploded view of another example input clutch. 
         FIG. 16B  is a front perspective exploded view of the input clutch of  FIG. 16A . 
         FIG. 17A  is a side assembled view of an example mode change sensor. 
         FIG. 17B  is a partial side assembled view of the mode change sensor of  FIG. 17A  rotated 90 degrees. 
         FIG. 18  is a side view of the output shaft with magnet arm assembly of  FIG. 17A . 
         FIG. 19A  is a partial side assembled view of the mode change sensor of  FIG. 17A  in a first position. 
         FIG. 19B  is a partial side assembled view of the mode change sensor of  FIG. 17A  in a second position. 
         FIG. 19C  is a partial side assembled view of the mode change sensor of  FIG. 17A  in a third position. 
         FIG. 19D  is a partial side assembled view of the mode change sensor of  FIG. 17A  in a fourth position. 
         FIG. 20  is a partial side assembled view of another mode change sensor using a Hall sensor with a concentrator. 
         FIG. 21A  is a side assembled view of another mode change sensor using an inductive sensor in a first position. 
         FIG. 21B  is a side assembled view of the mode change sensor of  FIG. 21A  in a second position. 
         FIG. 22A  is a partial side assembled view of the mode change sensor of  FIG. 21A  illustrating an inset view of inductive sensing coils. 
         FIG. 22B  a partial cutaway side assembled view of the mode change sensor of  FIG. 21A  except the sensor is moved to the front of the clutch face. 
         FIG. 23A  is a top view of inductive sensor coils. 
         FIG. 23B  is a side view of the inductive sensor coils of  FIG. 23A . 
         FIG. 24  is a top view of inductive sensor coils. 
         FIG. 25A  is a partial cutaway side assembled view of an inductive sensor in a first position. 
         FIG. 25B  is a partial cutaway side assembled view of the inductive sensor of  FIG. 25A  in a second position. 
         FIG. 26A  is a partial side assembled view of a two coil radial inductive sensor in a first position. 
         FIG. 26B  is a partial side assembled view of the two coil radial inductive sensor of  FIG. 26A  in a second position. 
         FIG. 27A  is a partial side assembled view of a two coil axial inductive sensor in a first position. 
         FIG. 27B  is a partial side assembled view of the two coil axial inductive sensor of  FIG. 27A  in a second position. 
         FIG. 27C  is a front view of the two coil axial inductive sensor of  FIG. 27A . 
         FIG. 28A  is a rear perspective exploded view of a depth adjustment nosecone with a depth collar adjustment. 
         FIG. 28B  is a front perspective exploded view of the depth adjustment nosecone of  FIG. 28A . 
         FIG. 29A  is an example flowchart of the operations of the screwgun of  FIGS. 1A-1H . 
         FIG. 29B  is an example flowchart of the trigger operated modes of operation of the screwgun of  FIGS. 1A-1H . 
         FIG. 29C  is an example flowchart of the lock on mode of operation of the screwgun of  FIGS. 1A-1H . 
         FIG. 29D  is an example flowchart of the auto start mode of operation of the screwgun of  FIGS. 1A-1H . 
     
    
    
     DETAILED DESCRIPTION 
     This document describes and illustrates a power tool, such as a screwgun (also referred to interchangeably as a screwdriver), that is a battery powered, cordless power tool. The power tool is generally configured to rotatably drive threaded fasteners into a workpiece. More specifically, in some implementations, the power tool may be used to drive drywall screws for affixing drywall to studs. To assist with driving threaded fasteners into a workpiece, the power tool includes an electronic mode select switch (also referred to as a digital mode select switch), which enables the power tool to be operated in one of multiple modes of operation. The modes of operation enable a motor in the power tool to be operated in various different drive modes. For example, the modes of operation include one or more of manual high speed, manual low speed, push start mode, lock on mode, and one or more rapid sequential modes. More specifically, the manual high speed mode and the manual low speed mode control the motor mode of operation and power delivery to the motor in cooperation with the actuation of a power switch (also referred to as a trigger) on the power tool. The other modes of operation control the motor mode of operation regardless of the actuation of the power switch. 
     In this manner, the electronic mode select switch provides different modes of operation for the power tool, including modes at different speeds, to address the technical needs and varied situations for driving fasteners into workpieces. This provides the user more options for operating the power tool in different fastening situations compared to a power tool with fewer speeds and fewer modes of operation. The user may select an appropriate mode of operation for a given fastening situation. By using an appropriate mode of operation for the given fastening situation, fastening efficiency may be improved and re-work of fastening jobs may be avoided because damage to fasteners and/or the workpiece can be minimized because the mode of operation may be better matched to the fastening situation. Furthermore, user fatigue caused by trying to control the motor speed using the power switch may be reduced by providing modes of operation that operate the power tool at different speeds using the power switch and in different modes without having to actuate the power switch. Also, the electronic mode select switch enables more modes of operation and a smoother transition between modes of operation when compared to a mechanical mode select switch. A visual indicator on the electronic mode select switch may be used to indicate the selected mode of operation. Each of the modes of operation is described in more detail below. 
     The power tool is ergonomically configured to enable simultaneous one-handed operation of the power tool and one-handed operation of both the power switch and the electronic mode select switch using the same hand. The electronic mode select switch and the power switch are both actuatable from outside the housing of the power tool. For example, the power switch may be located on a handle portion of the housing and the electronic mode select switch may be located on a motor housing portion of the housing. More specifically, for instance, the electronic mode select switch may be located on a top surface of the motor housing portion. The housing is ergonomically configured with multiple gripping regions to enable multiple, different one-handed grip positions by the user, while simultaneously providing access to the electronic mode select switch on the motor housing portion and the power switch on the handle portion. The ergonomic configuration of the power tool provides comfort during operation of the power tool for extended periods of time, which may reduce user fatigue during the extended use periods. The ergonomic configuration also provides for one-handed ease of operation using the various different modes of operation. Additionally, a belt clip (also referred to as a clip or tool clip) may be located in a same area on the motor housing portion as the electronic mode select switch. The belt clip may protect the electronic mode select switch from physical damage due to unintended drops of the power tool and/or unintended banging of the power tool against a foreign object and may provide a convenient place to retain the power tool on a user&#39;s belt or other stationary object when not in use. 
     As mentioned above, the power tool includes multiple different modes of operation. For some of the modes of operation, the power tool includes a sensing mechanism (also referred to as a sensor or a mode change sensor) that is used to detect and trigger one or more of the modes of operation. The sensor, which may be a Hall sensor, an inductive sensor, or other type of sensor, senses a position of the output clutch when the input clutch is engaged and the sensor sends a signal that causes the motor to start. The sensor may be located on or in front of the output clutch, as illustrated and described below in more detail, which increases the accuracy of sensing the position of the output clutch and reduces the complexity of prior sensing linkages, which were at least partially located behind the output clutch. 
     Furthermore, the power tool includes a multiple part clutch arrangement in combination with a planetary gear transmission. In one example arrangement, an input clutch face and corresponding clutch surfaces are integrated as part of the output planet gear carrier of the transmission. The integrated clutch and transmission components provides for a more compact clutch and transmission assembly and for an overall more compact and ergonomically configured, quieter operating power tool. These features and other features are described in more detail below with respect to the figures. 
     Referring to  FIGS. 1A-1H and 2 , in one example implementation, a power tool  10  is illustrated. In the illustrated examples, the power tool  10  is a screwgun, which also may be referred to as a screwdriver, that is configured to rotatably drive threaded fasteners into a workpiece.  FIG. 1A  is a front perspective view of the example screwgun.  FIG. 1B  is a rear perspective view of the screwgun of  FIG. 1A .  FIG. 1C  is a right side view of the screwgun of  FIG. 1A .  FIG. 1D  is a front view of the screwgun of  FIG. 1A .  FIG. 1E  is a left side view of the screwgun of  FIG. 1A .  FIG. 1F  is a rear view of the screwgun of  FIG. 1A .  FIG. 1G  is a top view of the screwgun of  FIG. 1A .  FIG. 1H  is a bottom view of the screwgun of  FIG. 1A .  FIG. 2  is left side cutaway view of an example screwgun. 
     The power tool  10  has a housing  12  having a front end portion  18 , a rear end portion  22 , and sidewalls defining a tool axis X-X. The housing includes a motor housing portion  13  that contains a motor  14  (e.g., a rotary motor) and a transmission housing portion  15  that contains a planetary gear transmission that transmits rotary motion from the motor  14  to an output spindle  26 . The motor housing portion  13  includes a bottom surface  17  and a top surface  19 , which is generally opposite the bottom surface  17 . The transmission housing portion  15  is coupled to the motor housing portion  13 . Coupled to the front end portion  18  of the transmission housing portion  15  and mechanically connected to the output spindle  26  is a working end or tool bit holder  16  for retaining a tool bit  31  (e.g., a drill bit or screw driving bit), as shown in  FIG. 2 , and defining a tool holder axis X-X. As shown, the tool bit holder  16  includes a hex bit retention mechanism. Further details regarding example tool holders are set forth in commonly-owned U.S. patent application Ser. No. 12/394,426 (now U.S. Pat. No. 8,622,401) and Ser. No. 14/186,088 (now U.S. Pat. No. 9,616,557), which are incorporated herein by reference. The working end of the tool bit holder  16  could encompass other elements, such as a different hex bit holder, a chuck, a nosepiece of a nailer or stapler, or a saw blade holder. As illustrated in  FIG. 2 , a removable depth adjust nosecone assembly  32  is coupled to the front end portion  18  of the housing  12 . The motor  14  drives the working end or tool bit holder  16  via the motor output shaft  51 , the transmission, and the output spindle  26 . A nosepiece  33  or magazine may optionally be coupled to the front end portion  18  of the housing  12 , as described and shown in the aforementioned U.S. patent application Ser. No. 14/186,088 (now U.S. Pat. No. 9,616,557), which is incorporated by reference. 
     Extending downward and slightly rearward of the housing  12  is a handle portion  40  in a pistol grip formation. The handle portion  40  has a proximal portion  42  coupled to the housing  12  and a distal portion  44  coupled to a battery receptacle  28 . The handle portion  40  also has a first front wall portion  43  and a second front wall portion  59  facing the tool bit holder  16  side of the tool, a rear wall portion  41  facing away from the tool bit holder  16  side of the tool, and sidewalls  49 . The handle portion  40  extends generally along a handle axis Y-Y that is at an obtuse angle α to the tool bit holder axis X-X and that lies along a midline of the handle portion  40 . For example, the angle α may be approximately 100-115 degrees, e.g., approximately 106 degrees, such that the distal portion  44  is located generally rearward and downward of the rear end portion  22  of the housing  12 . It should be understood that this angle can be varied among a wide range of angles. The handle portion  40  also includes a finger rest recess  47  and a rear concave recess  48  for use when gripping the power tool  10  in one-handed operation. 
     The motor  14  may be powered by an electrical power source, e.g., a battery (not shown), which is coupled to the battery receptacle  28 . In some implementations, the motor  14  may be a brushless motor. It is understood that the motor  14  may be implemented as other types of motors. A trigger  30 , also referred to as a power switch, is coupled to the handle portion  40  adjacent the motor housing portion  13  of the housing  12 . The trigger  30  electrically connects the battery (or other source of power) to the motor  14  via a motor controller  29  for controlling power delivery to the motor  14 . The motor controller  29  is in electrical communication with the motor  14 . The motor controller  29  may include a memory module and a microcontroller. The trigger  30  defines a trigger axis Z-Z extending along the direction of trigger travel, which is generally perpendicular to the handle axis Y-Y. A light unit (e.g., an LED)  27  may be disposed on the battery receptacle  28  and may be angled to illuminate an area in front of the tool bit holder  16 . Power delivery to the light unit  27  may be controlled by the trigger  30  and the motor controller  29 , or by a separate switch on the tool. As shown in the drawings, the power tool is a battery powered cordless screwgun, also referred to as a screwdriver. However, it should be understood that the tool may be any type of corded, cordless, pneumatic, or combustion powered tool, such as a drill, an impact driver, a wrench, a hammer, a hammer drill, a nailer, a stapler, a saw, a grinder, a sander, or a router. 
     As mentioned above, the motor  14  drives the working end or tool bit holder  16  via the motor output shaft  51 , the transmission, and the output spindle  26 . The transmission may be a planetary gear transmission that includes a sun gear  52  (also referred to as a pinion), a planet carrier  53  for holding one or more (e.g., three) planet gears  20 , and a ring gear  54  that is fixed around the planet gears. The sun gear  52  is operably coupled to the motor output shaft  51 , which rotatably drives the sun gear  52 . The sun gear  52  is operably coupled to the planet gears  20  where the teeth of the sun gear  52  rotatably drive the planet gears  20 . The planet gears  20  rotate around axes that revolve around the sun gear  52 . The ring gear  54  binds and encases the planet gears  20  with the planet gears  20  rotating within the fixed ring gear  54 . 
     The transmission is operably coupled to a clutch system that includes an input clutch  55  integrated with the planet carrier  53 , an intermediate clutch  56 , a clutch spring  57 , and an output clutch  58 . The output clutch  58  is operably coupled to the output spindle  26  and the tool bit holder  16 . The output clutch  58  moves axially with the with the output spindle  26  and the tool bit holder  16 . In general operation, the rotation of the motor output shaft  51  rotatably drives the sun gear  52  and the planet carrier  53  with the integrated input clutch  55  and the intermediate clutch  56 . An axial gap between the intermediate clutch  56  and the output clutch  58  keeps the output clutch disengaged from the intermediate clutch  56  until an axial force is exerted on the tool bit holder  16 , such as by a user pressing the tool bit holder  16  into a workpiece. The axial force exerted on the tool bit holder axially moves the tool bit holder  16  and the output spindle  26 , which is coupled to the tool bit holder  16 , and the output clutch  58 , which is coupled to the output spindle  26 , and compresses the clutch spring  57  until the output clutch  58  engages the rotating intermediate clutch  56 . The rotating intermediate clutch  56  imparts rotation to and rotatably drives the output clutch  58 , the output spindle  26 , and the tool bit holder  16 . Additional details and description of the transmission and clutch assemblies are provided below in more detail with respect to  FIGS. 13A-16B , including different implementations. 
     The power tool  10  includes an electronic mode select switch  60 . The electronic mode select switch  60  provides an interface for a user to change the power tool modes of operation using an electronic switch instead of a mechanical switch. The electronic mode select switch  60  is actuatable from outside the housing  12 . The electronic mode select switch  60  is disposed on the motor housing portion  13 . While the electronic mode select switch  60  is illustrated as being disposed on a top surface  19  of the motor housing portion  13 , it is understood that the electronic mode select switch  60  may be disposed in other locations on the motor housing portion  13  such as, for example, on either side of the motor housing portion  13  or on a back of the motor housing portion  13  above the proximal portion  42  of the handle portion  40 . As illustrated in  FIG. 2 , the electronic mode select switch  60  includes a printed circuit board (PCB)  61  that has a microcontroller and a memory module. Additional details, including the details of the various modes of operation, are provided below with respect to  FIGS. 3A-9 . 
     Furthermore, a sensor (also referred to interchangeably as a mode change sensor) may be used to detect movement of the output spindle  26  for use in one or more of the modes of operation. When the sensor detects axial movement of the output spindle  26 , such as when the tool bit  31  engages a workpiece, the sensor sends a signal that causes the power tool  10  to operate and drive the fastener into the workpiece. When the sensor detects the axial movement of the output spindle  26  returning to its original position, then the sensor sends a signal that causes the power tool to stop driving the fastener into the workpiece. The sensor assembly includes a sensed member that moves together with the output spindle  26  and a sensing member that remains stationary relative to the sensed member and that senses movement of the sensed member relative to the sensing member. Alternatively, the sensing member could move together with the output spindle  26 , while the sensed member remains stationary relative to the sensing member. For example, in the implementation of  FIG. 2 , a sensor assembly  78  is illustrated as including a sensing member  79  with a Hall sensor  92  and a sensed member  89  including a magnet arm assembly  80 . Additional details, including details of various other sensor implementations, are provided below with respect to  FIGS. 17A-27C . 
     The power tool  10  includes a clip  70 , which also may be referred to interchangeably as a tool belt clip, a belt clip, a tool clip, a removable clip, and a hook. The clip  70  is disposed on the top surface  19  of the motor housing portion  13  and is secured to the motor housing portion  13  using removable fasteners. In this manner, the clip  70  is removable from the power tool  10 . In some implementations, the clip  70  may be integral with the power tool. The clip  70  enables the power tool  10  to hang from various surfaces, hooks, hangars, tool belt, and other objects. In some implementations, a portion of the clip  70  at least partially surrounds the electronic mode select switch  60  and, since the clip  70  is raised above top surface  19  of the motor housing portion  13 , provides physical protection for the electronic mode select switch  60 , which is recessed in the top surface  19 . The clip  70  is illustrated and described in more detail below with respect to  FIGS. 3A-4 . 
     Referring to  FIGS. 3A-9 , the electronic mode select switch  60  and the clip  70  are illustrated in more detail. The power tool  10  illustrated in  FIGS. 3A-9  may be the same power tool  10  and include the same features and functions as power tool  10  of  FIGS. 1A-2 , where the example implementation illustrated is a screwgun.  FIG. 3A  is a top rear perspective view of an example screwgun (i.e., power tool  10 ) with a removable clip  70 .  FIG. 3B  is a top rear perspective view of the screwgun (i.e., power tool  10 ) of  FIG. 3A  with an exploded view of the removable clip  70 .  FIG. 4  is a partial rear perspective cutaway view of the screwgun (i.e., power tool  10 ) of  FIG. 3A .  FIG. 5  is a partial top rear perspective view of the screwgun (i.e., power tool  10 ) of  FIG. 3A  with the removable clip  70  removed.  FIG. 6  is a partial right side cutaway view of the screwgun (i.e., power tool  10 ) of  FIG. 3A  with the removable clip  70  removed.  FIG. 7  is a side view of the electronic mode select switch  60  from the screwgun (i.e., power tool  10 ) of  FIG. 3A .  FIG. 8  is a perspective view of the electronic mode select switch  60  of  FIG. 7 .  FIG. 9  is an example schematic of an example indicator for the electronic mode select switch  60 . 
     As mentioned above, in some implementations, the electronic mode select switch  60  and the clip  70  are disposed on the top surface  19  of the motor housing portion  13  of the power tool  10 . In this manner, the electronic mode select switch  60  and the clip  70  are located in a same area on the motor housing portion  13 . The clip  70  is a removable clip that is secured to the top surface  19  using fasteners  71  that are received through slots  72  of the clip  70  and received into a fastener receiver  73  on the top surface  19  of the power tool  10 . The fasteners  71  are removable to enable the clip  70  to be removed and re-assembled as desired. The clip  70  also includes two feet  75  that hook into the motor housing portion  13  for additional support. 
     The clip  70  is raised above the top surface  19 , while the electronic mode select switch  60  is recessed into the top surface  19 . In this manner, the clip  70  provides physical protection to the electronic mode select switch  60  and may prevent unintended selection of the electronic mode select switch  60  and may prevent damage to the electronic mode select switch  60  due to a drop of the power tool  10  or knocking the power tool  10  into another object. The top surface  19  also includes a rib  76  that is disposed around and encircles or at least partially surrounds the electronic mode select switch  60 . The rib  76  is raised above the top surface  19  and may provide protection to the electronic mode select switch  60  against drops or other accidents when the clip  70  is removed. 
     The top surface  19  also may include multiple air vents  77  that aid in cooling the power tool  10  and, specifically, the motor and electrical and electronic components. The air vents  77  are air intake vents that receive air external to the power tool  10  and use the air for cooling. In some implementations, the air vents  77  are disposed on the top surface  19  on either side of the electronic mode select switch  60  adjacent to the fastener receiver  73 . It is understood that the air vents  77  may be located at other points on the top surface  19  and/or at other points on the motor housing portion  13 . 
     The electronic mode select switch  60  provides an interface for user selection of multiple different modes of operation of the power tool  10 . The electronic mode select switch  60  is electrically coupled to (i.e., in electrical communication with) the motor controller  29  and may be used to electronically control the mode of operation of the power tool  10  and the motor. The modes of operation may include manual high speed, manual low speed, push start mode, lock on mode, and multiple, different rapid sequential modes. The modes of operation are selected by the user depressing the electronic mode select switch  60 . The modes of operation may be programmed in a particular order and the user may cycle through the modes of operation by depressing the electronic mode select switch  60 . The electronic mode select switch  60  may include the PCB  61 , which includes a microcontroller  62 , a memory module  63 , and an indicator  64 . The memory module  63  may store the instructions for the different modes of operation, including the sequential order for activating the modes. The microcontroller  62  may perform the instructions stored in the memory module  63  and communicates the instructions to the motor controller  29 . The indicator  64  is configured to provide a visual indication to the user of the selected mode of operation. 
     For the manual high speed mode and the manual low speed mode, the electronic mode select switch  60  is used in conjunction with the trigger (trigger  30  of  FIG. 2 ). First the electronic mode select switch is selected to place the mode of operation in the manual high speed mode or the manual low speed mode and then the trigger  30  is used to turn the motor and the power tool on and off. In some implementations, the trigger  30  is a variable speed trigger that is used to control the amount of power delivered to the motor (and thus its operating speed) to be variable based on the travel distance of the trigger  30  or the amount of user pull of the trigger  30 . In some implementations, the trigger  30  functions as an on-off switch so that the amount of the power delivered to the motor (and thus the operating speed of the motor) remains substantially constant regardless of the travel distance of the trigger so long as it has been actuated. 
     In manual high speed mode, the trigger  30  is used to actuate the motor by the user pulling the trigger  30 . When the trigger  30  is pulled by the user, the motor turns ON at the highest or maximum power and/or operating speed of the power tool  10  or has a variable speed up to the highest or maximum power and/or operating speed based on the amount of pull on the variable speed trigger. When the trigger  30  is released, the motor turns OFF and the power tool  10  turns OFF. 
     In the manual low speed mode, the trigger  30  is used to actuate the motor by the user pulling on the trigger  30 . When the trigger  30  is pulled by the user, the motor turns ON at a reduced percentage of the highest or maximum operating speed of the power tool or has a variable power or speed up to a reduced percentage of the full operating speed of the power tool  10  based on the amount of pull on the variable speed trigger. In either case, the percentage of the full operating speed may be configurable by a user. In some implementations, the percentage of the full operating speed may be preset. For example, the percentage of the full operating speed may be set to 75% of the full operating speed. In operation, when the mode is set to the manual low speed and the trigger is fully pulled all the way, the motor turns ON and operates at 75% of the full power and/or operating speed. In this manner, a full trigger pull operates at this set lower speed. In some implementations, the variable trigger may be pulled less and the motor and power tool operate at an even lower percentage of the full power and/or operating speed depending on how far the trigger is pulled. In some implementations, the motor remains at a substantially constant reduced percentage of power and/or motor speed regardless of the amount of trigger travel, so long as the trigger has been actuated. When the trigger is released, the motor and the power tool turn OFF. 
     The use of the manual low speed mode may assist in maximizing user productivity and reducing user fatigue. The manual low speed mode also may reduce and/or eliminate fasteners that break and/or burn up from too high of an operating speed. The manual low speed mode also may reduce and/or eliminate broken fastener threads from thin wall sheet metal applications. 
     The push start mode is another mode of operation that is actuated by using the electronic mode select switch  60  to select the push start mode. The push start mode also may be referred to as auto start mode. In the push start mode, the trigger  30  is not used to actuate the motor and the power tool  10 . In the push start mode, the initial motor state is that the motor is not running. The sensor assembly  78 , which may include a nosepiece switch, detects movement of the output spindle towards the clutch, for example, when the user pushes the power tool  10  against a workpiece to drive a fastener into the workpiece. When the sensor assembly  78  detects the movement, the sensor assembly sends a signal to the motor controller to turn the motor ON. The motor turns ON, the clutch is engaged by the pushing movement of the power tool  10  against the workpiece, and the fastener is driven into the workpiece. After the fastener is driven into the workpiece, the output spindle  26  returns to its initial position. The sensor assembly  78  detects the movement of the output spindle  26  to its original position and the sensor assembly sends a signal to the motor controller to turn the motor OFF. 
     In some implementations, the push start mode may include only one speed option. For example, the motor may only operate at full operating speed in push start mode that has only one speed option. In some implementations, the push start mode may include a high speed option and a low speed option. In a push start high speed mode, the engagement of the workpiece by pushing the power tool  10  against the workpiece, automatically turns the motor on at full operating speed based on the sensor assembly detecting the movement of the output spindle  26 . In a push start low speed mode, when the sensor assembly detects the movement of the output spindle  26 , the motor is turned ON to a percentage of the full operating speed, which may be a configurable percentage of the full operating speed or a preset percentage of the full operating speed, similar to the manual low speed mode. 
     Another mode of operation is the lock on mode of operation. The lock on mode is actuated by using the electronic mode select switch to select the lock on mode. When the user fully pulls and releases the trigger  30 , the motor turns on full operating speed and the motor remains ON until the user fully pulls and releases the trigger  30  again. For instance, a partial trigger pull will not turn ON the motor in this mode and a partial trigger pull will not turn OFF the motor in this mode. In lock on mode, continuous power is delivered to the motor upon a single actuation and release of the power switch. With the lock on mode of operation, the motor remains turned ON as the user engages and disengages from a workpiece to drive fasteners. The clutch engages and disengages with the depressing and release of the power tool  10  against the workpiece. This mode of operation enables a faster pace of driving fasteners because the motor remains fully ON resulting in no lag time between driving fasteners. 
     In some implementations, the modes of operation include one or more rapid sequential modes. The rapid sequential modes are similar to the push start mode except that the motor remains running for a period of time after the sensor assembly detects the output spindle has returned to its initial position instead of the motor turning OFF. In a rapid sequential mode, the electronic mode select switch  60  is used to select the mode. When the user pushes the power tool  10  against the workpiece, the sensor assembly detects the movement of the output spindle  26  and sends a signal to start the motor. The user then drives a fastener into the workpiece. When the sensor assembly detects the output spindle  26  has returned to its initial position, the sensor assembly sends a signal to turn OFF the motor. The motor remains on for a period of time, which may be a preset time or may be a time adjustable by a user. For example, the motor may remain on for 3 seconds. The motor may be set to remain on for other periods of time. This enables another fastener to be driven within the period of time that the motor is still at full operating speed. If another fastener is driven, the period of time resets when the output spindle  26  returns to its initial position and the sensor assembly sends a signal to turn off the motor. If no drive event occurs during the period of time, the motor turns off and waits for the next sensed movement of the output spindle  26  to turn on again. 
     In some implementations of the rapid sequential mode, the motor speed may drop to a percentage of the full operating speed (e.g., 75% of the full operating speed) during the period of time instead of staying on at full operating speed. If the sensor assembly detects movement of the output spindle  26  to drive another fastener, the motor increases to full operating speed and then returns to the percentage of the full operating speed after the fastener is driven for the period of time. If no drive event occurs during the period of time, the motor turns off and waits for the next sensed movement of the output spindle  26  to turn on again. 
     Referring to  FIG. 9 , the indicator  64  provides a visual indication to the user of the current mode of operation. In this example, three lights  65 - 67  (e.g., light emitting diodes (LEDs)) may be used to indicate the current mode of operation. The lights  65 - 67  may be used alone and in combination to indicate a particular mode. The user may cycle through the modes of operation by depressing the electronic mode select switch, which causes the indicator  64  and the lights  65 - 67  to change with each selection of the electronic mode select switch. For example, when only light  65  is illuminated, the mode of operation may be manual low speed. When only light  66  is illuminated, the mode of operation may be manual high speed. When lights  66  and  67  are illuminated together, the mode of operation may be push start mode. When lights  65 ,  66 , and  67  are illuminated, the mode of operation may be lock on mode. The fixed symbol  68  also provides an indication to the user that the lock on mode is functional when all three lights  65 - 67  are illuminated. It is understood that this is merely one example of how the indicator  64  may be used to indicate the particular modes of operation to the user and that the lights  65 - 67  may be assigned to indicate other modes. 
     Referring to  FIGS. 10A-12B , various different user hand positions for gripping the power tool  10  are illustrated. The power tool  10  may be the same power tool  10  as illustrated in  FIGS. 1A-1H  and include the same reference numbers to refer to the same components. For example,  FIGS. 10A-10D  illustrate different views of a power tool  10  being gripped in a first position.  FIG. 10A  is a right side view of a screwgun being gripped in a first position.  FIG. 10B  is a left side view of the screwgun of  FIG. 10A  being gripped in the first position.  FIG. 10C  is a top view of the screwgun of  FIG. 10A  being gripped in the first position.  FIG. 10D  is a top view of the screwgun of  FIG. 10A  being gripped in the first position with the thumb near the electronic mode select switch. 
       FIGS. 11A-11B  illustrate different views of the power tool  10  being gripped in a second position.  FIG. 11A  is a right side view of the screwgun of  FIG. 10A  being gripped in a second position.  FIG. 11B  is a left side view of the screwgun of  FIG. 10A  being gripped in the second position. 
     As shown in  FIGS. 10A-11B , the power tool  10  is ergonomically configured to enable simultaneous one-handed operation of the power tool and one-handed operation of both the trigger  30  (also referred to as a power switch) and the electronic mode select switch  60  using the same hand. The electronic mode select switch  60  and the trigger  30  are both actuatable from outside the housing of the power tool. For example, the trigger  30  may be located on a handle portion  40  of the housing  12  and the electronic mode select switch  60  may be located on a motor housing portion  13  of the housing  12 . More specifically, for instance, the electronic mode select switch  60  may be located on a top surface  19  of the motor housing portion  13 . The housing  12  is ergonomically configured with multiple gripping regions to enable multiple, different one-handed grip positions by the user, while simultaneously providing access to the electronic mode select switch  60  on the motor housing portion  13  and the trigger  30  on the handle portion  40 . The ergonomic configuration of the power tool  10  provides comfort during operation of the power tool for extended periods of time, which may reduce user fatigue during the extended use periods. The ergonomic configuration also provides for one-handed ease of operation using the various different modes of operation. 
     Referring also back to  FIG. 1E , the power tool  10  includes a housing  12 , also referred to as an ergonomic housing, designed to be contoured to a user&#39;s hand. The housing  12  includes a first gripping region  34  on a top portion of the motor housing portion  13 , a second gripping region  36  on the rear wall portion  41  of the proximal portion  42  of the handle portion  40 , a third gripping region  35  on a bottom portion of the motor housing portion  13  below the first gripping region  34 , a fourth gripping region  38  on the rear wall portion  41  of the distal portion  44  of the handle portion  40 , a fifth gripping region  45  on a front wall portion  43  of the proximal portion  46  of the handle portion  40  adjacent to the trigger  30 , and a sixth gripping region  37  on the front wall portion  43  of the proximal portion  46  of the handle portion  40  distal of the fifth gripping region  45  and adjacent the battery receptacle  28 . One or more of the gripping regions  34 ,  35 ,  36 ,  38 ,  45 ,  37  may be formed or covered with an elastomeric material, such as rubber or a resilient plastic material, and may include one or more ridges or recesses to facilitate gripping of these regions. For ease of illustration the gripping regions  34 ,  35 ,  36 ,  38 ,  45 ,  37  are not illustrated in the other  FIGS. 10A-11B . 
     The ergonomic grip facilitates ergonomic gripping of the tool by a user&#39;s hand in two different grip positions during operation of the tool.  FIGS. 10A-11B  illustrate the anatomical parts of a user&#39;s hand. Generally, a user&#39;s hand includes a palm  101  to which is connected a thumb  102 , a forefinger  104 , a middle finger  106 , a ring finger  108 , and a pinky finger  110 . A web  112  of muscles connects the base of the thumb  102  and forefinger  104 . In addition, the palm  101  includes a center region flanked by two fleshy pads in the form of a thenar eminence on the thumb side of the palm and the hypothenar eminence on the pinky side of the palm. Further, there are fleshy pads on the palm  101  at the base of the thumb  102  and each finger  104 ,  106 ,  108 , and  110 . 
     In the first gripping position illustrated in  FIGS. 10A-10D , the thumb  102  grips the power tool  10  on the concave recess on one side of the motor housing portion  13  and the forefinger  104  grips the power tool  10  on the concave recess on the opposite side of the motor housing portion  13 . The middle finger  106  grips the power tool  10  on the finger rest recess  47 , which is located on the handle portion  40  near the bottom surface of the motor housing portion  13 . The ring finger  108  and the pinky finger  110  grip the trigger  30  on the handle portion  40 . In this manner, the finger rest recess  47  provides a gripping location for the middle finger  106  to provide leverage to enable the thumb  102  to move easily from the concave recess on the motor housing portion ( FIG. 10C ) to the electronic mode select switch on the top surface of the motor housing portion ( FIG. 10D ). Of course, the user may just as easily move the thumb  102  back from the electronic mode select switch to the concave recess, all while maintaining a steady, reliable, and comfortable grip on the power tool  10 . In this manner, the user may operate the power tool with one hand and simultaneously change modes of operation with the same hand by moving the thumb  102  from the side of the power tool to the top of the power tool  10 . 
     In the second gripping position illustrated in  FIGS. 11A-11B , the thumb  102  is wrapped around the handle portion  40 . The forefinger  104  grips the power tool  10  on the concave recess on the motor housing portion  13 . The middle finger  106  grips the trigger  30  on the handle portion  40  and the ring finger  108  and the pinky finger  110  grip the handle portion  40  below the trigger  30 . In this manner,  FIGS. 11A-11B  illustrate a second gripping position that is different than the first gripping position illustrated in  FIGS. 10A-10D . Both gripping positions enable one-handed operation of the power tool  10  that enables the user to maintain a comfortable and steady grip for periods of time while using the power tool  10  on a workpiece(s). 
     Referring to  FIGS. 12A and 12B , features are illustrated, including example dimensions, that provide for a housing  12  with superior ergonomics.  FIG. 12A  is a left side view of the screwgun of  FIG. 1A .  FIG. 12B  is a rear view of the screwgun of  FIG. 1A . The handle portion  40  has a first depth D 1  and a first width W 1  at the trigger  30 , a second depth D 2  and a second width W 2 , and a third depth D 3  and a third width W 3  at the base of the handle portion  40 . The first depth D 1  is slightly greater than the second depth D 2 , which is greater than the third depth D 3 . For example, the first depth D 1  is approximately 45 mm to 55 mm (e.g., approximately 50 mm), the second depth D 2  is approximately 40 mm to 50 mm (e.g., approximately 48 mm), and the third depth D 3  is approximately 38 mm to 48 mm (e.g., approximately 45 mm). The first width W 1  is greater than the second width W 2 , which is approximately equal to the third width W 3 . For example, the first width W 1  is approximately 37 mm to 42 mm (e.g., approximately 39 mm), the second width W 2  is approximately 31 mm to 36 mm (e.g., approximately 34 mm), and the third width W 3  is approximately 28 mm to 35 mm (e.g., approximately 33 mm). The concave recesses on either side of the motor housing portion  13  have a height H 1 , which is approximately 14 mm to 20 mm (e.g., approximately 16 mm). 
     The housing  12  further includes a fourth depth D 4  measured from the trigger  30  to the rear concave recess  48  of approximately 80 mm to 85 mm (e.g., approximately 82 mm). The ergonomics of the housing  12  also form an ellipse-shape centered on the trigger  30  with a major axis MA 1  extending from the top surface of the motor housing to the battery receptacle and having dimensions of approximately of 142 mm to 147 mm (e.g., approximately 145 mm) and a minor axis MI 1  extending from the rear of the handle to the front of the motor housing and having dimensions of approximately of 128 mm to 132 mm (e.g., approximately 130 mm). 
     Referring to  FIGS. 13A-15 , an example transmission and clutch assembly for the power tool  10  is illustrated.  FIG. 13A  is a rear portion perspective exploded view of an example transmission and clutch assembly for a screwgun.  FIG. 13B  is a front portion perspective exploded view of the transmission and clutch assembly of  FIG. 13A .  FIG. 14  is a side view of an assembled transmission and clutch assembly for a screwgun.  FIG. 15  is a perspective view of an example planet carrier  53  with an integrated input clutch  55 . 
     As mentioned above, the motor (not shown) drives the working end or tool bit holder  16  via the motor output shaft (not shown), the output spindle  26 , and the transmission and clutch assembly. The transmission and clutch assembly includes a gear and clutch case front portion  83  and a gear and clutch case rear portion  84 , in which the transmission and clutch components are at least partially disposed. A bearing  81  is disposed in the gear and clutch case front portion  83 . In some implementations, and as illustrated, the transmission may be a planetary gear transmission that includes a sun gear  52  (also referred to as a pinion), a planet carrier  53  for holding three planet gears  20 , and a ring gear  54  that is fixed around the planet gears. Pins  82  (also referred to as carrier pins) are configured to secure and hold the planet gears  20  in the planet carrier  53 . The sun gear  52  is operably coupled to the motor output shaft  51 , which rotatably drives the sun gear  52 . The sun gear  52  is operably coupled to the planet gears  20  where the teeth of the sun gear  52  rotatably drive the planet gears  20 . The planet gears  20  rotate around axes that revolve around the sun gear  52 . The ring gear  54  binds and encases the planet gears  20 . A bearing  39  (also referred to as an output spindle bearing) supports the output spindle  26 . As shown in  FIG. 14 , a planet carrier bearing  85  support the planet carrier  53 . 
     The transmission is operably coupled to a clutch system that includes an input clutch  55  integrated with the planet carrier  53 , an intermediate clutch  56 , a clutch spring  57 , and an output clutch  58 . The output clutch  58  is operably coupled to the output spindle  26  and the tool bit holder  16 . The output clutch  58  moves axially with the with the output spindle  26  and the tool bit holder  16 . In general operation, the rotation of the motor output shaft rotatably drives the sun gear  52  and the planet carrier  53  with the integrated input clutch  55  and the intermediate clutch  56 . An axial gap between the intermediate clutch  56  and the output clutch  58  keeps the output clutch disengaged from the intermediate clutch  56  until an axial force is exerted on the tool bit holder  16 , such as by a user pressing the tool bit holder  16  into a workpiece. The axial force exerted on the tool bit holder axially moves the tool bit holder  16  and the output spindle  26 , which is coupled to the tool bit holder  16 , and the output clutch  58 , which is coupled to the output spindle  26 , and compresses the clutch spring  57  until the output clutch  58  engages the rotating intermediate clutch  56 . The rotating intermediate clutch  56  imparts rotation to and rotatably drives the output clutch  58 , the output spindle  26 , and the tool bit holder  16 . 
     Referring more specifically to  FIG. 15 , the input clutch  55  is integrated with the planet carrier  53 . With the input clutch  55  integrated with the planet carrier  53 , the overall transmission and clutch assembly is more compact and enables users to use the power tool in tighter and more confined spaces, where manoeuvrability may be challenging. The input clutch  55  includes multiple clutch faces  551 ,  552 , and  553 . The clutch faces  551 ,  552 , and  553  mesh and interact with corresponding clutch faces on the intermediate clutch  56 . In general, the input clutch  55  and the intermediate clutch  56  remain axially stationary, while the output clutch  58  is a movable clutch that moves in an axial direction to engage the intermediate clutch  56  when the spring force of the clutch spring  57  is overcome and to disengage the intermediate clutch  56  when the spring force of the clutch spring  57  is released. 
     Referring also to  FIG. 17A , the sensor assembly  78  comprises a sensed member  89  including a magnet arm assembly  80  and a sensing member  79  including a Hall sensor  92 . The magnet arm assembly  89  includes a radial arm portion  89   a  that extends radially outward from the output spindle to a radius that is greater than a radius of the output clutch  58 , an axial arm portion  89   b  that extends axially rearward across at least a portion of the output clutch  58 , and, a magnet  86  that is coupled to the axial arm portion  89   b  approximately even with the output clutch  58 . The magnet arm  80  is coupled to the output clutch  58 . The magnet arm assembly  80  and magnet  86  move axially when the output clutch  58  moves axially. In this manner, the axial position of the magnet arm assembly  80  and magnet  86  may be sensed by the Hall sensor  92  to detect the movement of the tool bit holder  16 , the output spindle  26 , and the output clutch  58  when the tool bit holder  16  is pressed against a workpiece. The detection of the movement of these components may be used to one or more of the modes of operation discussed above such as, for example, the push start mode(s) and the rapid sequential mode(s). At least a portion of the magnet arm assembly  80  is located forward of the output clutch  58  on the side closer to the gear and clutch case front portion  83 . The magnet arm assembly  80  and the Hall sensor  92  are discussed in more detail below with respect to  FIGS. 17A-19D . 
     Referring to  FIGS. 13C-13J , the transmission and clutch assembly also may include a braking mechanism  88 , also referred to as a clutch stop.  FIG. 13C  illustrates an exploded view of the clutch and transmission assembly with the braking mechanism  88  and  FIG. 13D  illustrates the braking mechanism component by itself. The braking mechanism may include a ring  90  and multiple legs  91 . As illustrated in  FIGS. 13E, 13G, 13H, and 13I  the legs  91  of the braking mechanism  88  extend from a point axially forward of the sensed member  89  of the sensor assembly  78  to a point axially rearward of the radial arm portion  89   a  of the sensor assembly  78  to engage stops  93  on the output clutch  58  when the output clutch  58  is in its forward position to prevent rotation of the output clutch  58  and the tool bit holder  16  when the output clutch  58  is disengaged from the intermediate clutch  56  and the input clutch  55 . This is also referred to as a “dead spindle” position. In this example, the braking mechanism  88  includes multiple legs  91  that engage stops  93  on the output clutch  58  when the output clutch  58  is in its forward position to prevent rotation of the output clutch  58  and the tool bit holder  16  when the output clutch  58  is disengaged from the intermediate clutch  56  and the input clutch  55 . 
     In  FIG. 13F , the stops  93  on the output clutch  58  are disengaged from the legs  91  on the braking mechanism  88 . For instance, as the output clutch  58  re-engages the intermediate clutch  56 , the stops  93  on the output clutch  58  disengage from the legs  91  on the braking mechanism  88  so that the output clutch  58  and the output spindle  26  may rotate. In  FIGS. 13H-13J , the braking mechanism  88  is illustrated as being integrated as part of the gear and clutch case  83 . For example, the braking mechanism  88  may be insert molded into the gear and clutch case  83 . 
     Referring to  FIGS. 16A and 16B , another example implementation of a transmission and clutch assembly is illustrated.  FIG. 16A  is a front perspective exploded view of another example input clutch.  FIG. 16B  is a rear perspective exploded view of the input clutch of  FIG. 16A . In this example, the input clutch  155  is not integrated with the planet carrier  153  and instead is a separate component. The pins  182  function as a securing mechanism to secure and hold the planets  120  in the planet carrier  153  and to hold the input clutch  155  to the planet carrier  153 . 
     In some implementations, the transmission may include a parallel axis transmission, similar to the one described in U.S. Pat. No. 7,469,753, which is incorporated herein by reference. 
     Referring to  FIGS. 17A-19D , an example sensor assembly  78  is illustrated. The sensor assembly  78  includes the magnet arm assembly  80  coupled to the output spindle  26 , the magnet  86 , and the Hall sensor  92  electrically connected to the electronic mode select switch  60 .  FIG. 17A  is a side assembled view of an example mode change sensor.  FIG. 17B  is a partial side assembled view of the mode change sensor of  FIG. 17A  rotated 90 degrees.  FIG. 18  is a side view of the mode change sensor of  FIG. 17A . 
     The magnet arm assembly  80  is coupled to the tool bit holder  16  side of the output clutch  58 , which is forward of the clutch spring  57  and the intermediate clutch  56 . In operation, the Hall sensor  92  senses the movement of the magnet  86  by detecting a change in polarity as the magnet moves axially. The Hall sensor  92  may be a bi-latching Hall sensor that uses the detected change in polarity of the magnet, due to the axial movement of the magnet  86 , to send signals to the electronic mode select switch  60 , which may be relayed to the motor controller. In some implementations, the Hall sensor may be an ordinary Hall sensor that detects the proximity of the magnet. 
     When the user applies pressure to the tool bit holder  16  against a workpiece, the tool bit holder  16 , the output spindle  26 , and the output clutch  58  with the attached magnet arm assembly  80  move axially to compress the clutch spring  57  towards the intermediate clutch  56 . The magnet  86  is fixed to the magnet arm assembly  80  and moves axially with the magnet arm assembly  80  and the output clutch  58 . As the magnet  86  moves across the Hall sensor  92  and the change of polarity is sensed, the Hall sensor  92  sends a signal to the electronic mode select switch  60 . If the current mode of operation is the push start mode or rapid sequential mode, the motor will turn ON responsive to the detected axial movement and the signal initiated by the Hall sensor  92 . 
     When the user releases the pressure of the tool bit holder  16  from the workpiece, the tool bit holder  16 , the output spindle  26 , and the output clutch  58  with the attached magnet arm assembly  80  move axially away from the intermediate clutch  56 . The magnet  86  is fixed to the magnet arm assembly  80  and moves axially with the magnet arm assembly  80  and the output clutch  58 . As the magnet  86  moves back across the Hall sensor  92  and the change of polarity is sensed, the Hall sensor  92  sends a signal to the electronic mode select switch  60 . If the electronic mode select switch  60  is in the push mode, the motor will turn OFF responsive to the detected axial movement and the signal initiated by the Hall sensor  92 . If the electronic mode select switch  60  is in the rapid sequential mode, the motor remains ON for the period of time responsive to the detected axial movement and the signal initiated by the Hall sensor  92 . 
       FIGS. 19A-19D  illustrate the operation of the magnet arm assembly  80  and the Hall sensor  92 .  FIG. 19A  is a partial side assembled view of the mode change sensor of  FIG. 17A  in a first position. In  FIG. 19A , the tool state is the motor is OFF and the push start mode is selected on the electronic mode select switch and in a standby state. The output clutch  58  is disengaged from the intermediate clutch  56 . The Hall sensor is looking for a magnetic pole change, where the “S” magnetic pole of the magnet  86  is positioned below the Hall sensor  92 . 
       FIG. 19B  is a partial side assembled view of the mode change sensor of  FIG. 17A  in a second position. In  FIG. 19B , output spindle  26 , the magnet arm assembly  80 , and the magnet  86  move axially from a home position and travel the distance marked by “distance traveled.” The axial movement moves the magnet  86  past the Hall sensor  92  such that the “N” pole of the magnet is positioned below the Hall sensor  92  and the Hall sensor  92  senses the magnetic pole change from “S” to “N”. The Hall sensor  92  sends a signal to turn the Motor ON. The Motor turns ON even though the output clutch  58  has not yet engaged the intermediate clutch  56 . 
       FIG. 19C  is a partial side assembled view of the mode change sensor of  FIG. 17A  in a third position. In  FIG. 19C , the axial movement of the output spindle  26 , the magnet arm assembly  80 , the magnet  86 , and the output clutch  58  continues to engage the rotating intermediate clutch  56 . The output clutch  58  engages the intermediate clutch  56  causing the output spindle  26  and the tool bit holder to rotate and drive a fastener into the workpiece. The tool state is the Motor is ON, the clutches are engaged and driving a fastener. The Hall sensor  92  is waiting for another change in polarity of the magnet. 
       FIG. 19D  is a partial side assembled view of the mode change sensor of  FIG. 17A  in a fourth position. In  FIG. 19D , the output clutch  58  disengages from the intermediate clutch  56  and the output clutch  58 , along with the magnet arm assembly  80  and the magnet  86 , move axially back to the home position. The output clutch  58  and the output spindle  26  stop rotating when the clutches disengage. As the magnet  86  moves axially, the Hall sensor  92  senses the change in polarity from “N” back to “S”. The Hall sensor  92  sends a signal to turn the Motor Off. If the electronic mode select switch  60  is in the push mode, the motor will turn OFF responsive to the detected axial movement and the signal initiated by the Hall sensor  92 . If the electronic mode select switch  60  is in the rapid sequential mode, the motor remains ON for the period of time responsive to the detected axial movement and the signal initiated by the Hall sensor  92 . 
     Referring to  FIG. 20 , another example implementation of a mode change sensor is illustrated.  FIG. 20  is a partial side assembled view of another mode change sensor using a Hall sensor  2092  with a concentrator  2094 . In some implementations, a Hall sensor  2092  may be used with a concentrator  2094  and a fixed permanent magnet  2096 . The concentrator  2094  directs or focuses a magnetic field on the output clutch. When the output clutch moves axially, the magnetic field passing through the Hall sensor  2092  changes and the Hall sensor  2092  sends a signal to turn the motor ON. When the output clutch moves axially again, the magnetic field passing through the Hall sensor  2092  reverses and the Hall sensor  2092  sends a signal to turn the motor OFF. 
     Referring to  FIGS. 21A-23B , other example implementations illustrate mode change sensor using an inductive sensor.  FIG. 21A  is a side assembled view of another mode change sensor using an inductive sensor in a first position.  FIG. 21B  is a side assembled view of the mode change sensor of  FIG. 21A  in a second position.  FIG. 22A  is a partial side assembled view of the mode change sensor of  FIG. 21A  illustrating an inset view of inductive sensing coils.  FIG. 22B  a partial cutaway side assembled view of the mode change sensor of  FIG. 21A .  FIG. 23A  is a top view of inductive sensor coils.  FIG. 23B  is a side view of the inductive sensor coils of  FIG. 23A . 
     In  FIGS. 21A and 21B , an inductive sensor board  2102  is used to detect a change in position/axial movement of the output clutch  2104 . The inductive sensor board  2102  is positioned above the output clutch  2104 .  FIG. 21A  shows the output clutch  2104  is a first disengaged position, where the output clutch  2104  is disengaged from the intermediate clutch  2106 . In  FIG. 21B , the inductive sensor board  2102  no longer senses the ferrous metal of the output clutch  2104  as the output clutch  2104  moves axially towards the intermediate clutch  2106 . Responsive to sensing this change, the inductive sensor board  2102  sends a signal to turn the motor ON. When the output clutch  2104  disengages from the intermediate clutch  2106 , the inductive sensor board  2102  senses the ferrous metal of the output clutch  2104  and sends a signal to turn the motor OFF. 
     In some implementations, the scheme can also be reversed and the inductive sensor board  2102  can look at the gap between the output clutch  2104  and the intermediate clutch  2106 . Then, when the output clutch  2104  moves into view, the inductive sensor board  2102  would detect the movement and turn the motor ON and OFF, as appropriate. 
       FIG. 22A  illustrates the details of the inductive sensor  2202  with a receiving coil  2220  on the top side of the printed circuit board and the sensing coil  2224  on the bottom (clutch) side of the printed circuit board, where the output clutch is in a forward position. 
       FIGS. 22B, 23A, and 23B  illustrate a two coil inductive sensor implementation. The printed circuit board  2302 , also referred to as an Auto Start Module, includes an inductive sensor using a side by side coil design to achieve the furthest sensing range with a first coil  2330  and a second coil  2340 . The switching distance S D  is a fixed distance from the sensor&#39;s surface where a conductive target will switch the sensor output signal from Low to High. The switching distance S D  is approximately 40% of the coil diameter with an approximate coil diameter of between 5 mm and 9 mm (e.g., approximately 7 mm) and an approximate switching distance S D  of between 2 mm and 3.6 mm (e.g., approximately 2.8 mm). The target for the inductive sensor is the output clutch  2304  and the distance from the inductive sensor to the target is the Target Distance or T D . 
     Referring to  FIG. 24 , the location of the inductive sensor coils is illustrated. The auto start module  2402  is housed inside the gear case behind the output clutch  2404 . The sense coil  2430  is positioned so the output clutch  2404  covers 100% of the coil diameter. 
     Referring to  FIGS. 25A and 25B , the output clutch  2504  is shown in a position at rest (or home position) ( FIG. 25A ) and during actuation ( FIG. 25B ). When the output clutch  2504  displacement is greater than the switching distance (T D &gt;S D ), the auto start module  2502  will send a HIGH signal to the motor. As the output clutch  2504  disengages from the motor, the T D &lt;S D  and the auto start module  2502  will send a LOW signal to stop the motor. 
     Referring to  FIGS. 26A and 26B , another example implementation of a mode change sensor that uses a two coil radial inductive sensor  2602  (also referred to as inductive sensor or inductive sensor board) is illustrated.  FIG. 26A  illustrates a partial side assembled view of a two coil radial inductive sensor  2602  in a first position with the output clutch  2604  disengaged from the intermediate clutch  2606  (i.e., the output clutch  2604  in rest position meaning no pressure is being applied by the user to a workpiece). The inductive sensor board  2602  is fixed in position in the gearcase disposed below the output clutch  2604 . The inductive sensor  2602  is positioned to detect movement of the output clutch  2604  towards the intermediate clutch  2606  by watching for a gap between the gear case  2608  and the output clutch  2604  when pressure is applied by the user against a workpiece. 
       FIG. 26B  illustrates a partial side assembled view of the two coil radial inductive sensor  2602  of  FIG. 26A  in a second position when the output clutch  2604  has moved towards to the intermediate clutch  2606  (i.e., the output clutch  2604  has moved into driving position to drive a fastener). The inductive sensor  2602  senses the gap  2610  between the gear case  2608  and the output clutch  2604  as the output clutch  2604  moves axially toward the intermediate clutch  2606 . Responsive to sensing the gap  2610 , the inductive sensor  2602  sends a signal to turn the motor ON and the output clutch  2604 , output spindle, and tool bit holder rotate to drive a fastener. When the output clutch  2604  disengages from the intermediate clutch  2606 , the output clutch  2604  returns to the rest position and the gap  2610  is closed. The inductive sensor  2602  senses the gap  2610  is closed and sends a signal to turn the motor OFF. 
     Referring to  FIGS. 27A-27C , another example implementation of a mode change sensor using an axial inductive sensor is illustrated. A donut-shaped induction sensor  2702  is used that is concentric with the output shaft axis of rotation. This allows the induction sensor  2702  to nest in the assembly and use less space. The induction sensor  2702  works by looking at the outside face of the output clutch  2704  and senses a change in the distance of the output clutch  2704  when the power tool is in use.  FIG. 27A  illustrates a partial side assembled view of a two coil axial inductive sensor  2702  in a first position with the output clutch  2704  engaged with the intermediate clutch  2706  is a drive mode. A gap  2710  is created when the output clutch  2704  is in the drive mode and the donut-shaped inductive sensor  2702  senses the gap  2710  and sends a signal via the wire to turn the motor ON.  FIG. 27B  illustrates a partial side assembled view of the two coil axial inductive sensor  2702  of  FIG. 27A  in a second position when the output clutch  2704  is disengaged from the intermediate clutch  2706  in the rest position. The gap  2710  is closed in this position and the inductive sensor  2702  senses the closed gap  2710  and sends a signal to turn the motor OFF.  FIG. 27C  illustrates a front view of the two coil axial inductive sensor  2702  of  FIG. 27A  showing its donut shape and location concentric with the output shaft. 
     In one or more of the mode change sensor implementations described above, a duty cycle method to “pulse” the sensor at a % duty cycle may be used to reduce electromagnetic interference (EMI). For example, at a 20% duty cycle, the sensor is on for 2 ms and off for 8 ms. This duty cycle is fast enough to detect the output clutch movement faster than a user can perceive the movement. Operating the inductive sensor on a duty cycle provides the advantage of much lower EMI emissions than if no duty cycle is used and the sensor is on for 100% of the time. 
     Referring to  FIGS. 28A and 28B , a depth adjustment nosecone  2800  with a depth adjustment collar  2802  is illustrated.  FIG. 28A  is a rear perspective exploded view of a depth adjustment nosecone  2800  with a depth adjustment collar  2802 .  FIG. 28B  is a front perspective exploded view of the depth adjustment nosecone  2800  of  FIG. 28A . The depth adjustment nosecone  2800  is removeable and is used to adjust the depth to which a screw can be driven. An example depth adjustment nosecone is described in commonly assigned U.S. Pat. No. 10,406,661 at col. 6, line 12 to col. 7, line 14, which is herein incorporated by reference. 
     In  FIGS. 28A and 28B , the depth adjust nosecone  2800  includes differences from the incorporated patent such as the depth adjustment collar  2802  has concave indexing recesses  2803  that are used to hold the depth adjustment collar  2802  in a fixed position. The spring holder assembly  2804  includes leaf springs  2806  that engage the concave indexing recesses  2803  as the depth adjustment collar  2802  rotates. 
       FIG. 29A  is an example flowchart of a process  2900  for controlling the operation of a power tool such as, for example, the power tool  10  of  FIGS. 1A-1H .  FIG. 29B  is an example flowchart of the trigger operated modes of operation of the screwgun of  FIGS. 1A-1H .  FIG. 29C  is an example flowchart of the lock on mode of operation of the screwgun of  FIGS. 1A-1H .  FIG. 29D  is an example flowchart of the auto start mode of operation of the screwgun of  FIGS. 1A-1H . Process  2900  is performed by the power tool  10 . More specifically, process  2900  may be performed using the components of the motor controller, which may include a memory module and a microcontroller, and/or the electronic mode select switch  60 , which includes a memory module  63  and a microcontroller  62 , as illustrated in  FIG. 7 . In some implementations, the motor controller may be a component separate from the power switch  30  and the electronic mode select switch  60  or the motor controller may be incorporated as a component of the power switch  30  or the electronic mode select switch  60 . 
     Referring to  FIG. 29A , process  2900  includes receiving a default operation mode ( 2902 ). In some implementations, the default operation mode includes the last operation mode of the power tool as stored in the memory module  63  of the electronic mode select switch  60 , as illustrated in  FIG. 7 . The last operation mode may be stored as an operation mode state in the memory module  63 . The memory module  63  may retain the operation mode state for a period of time. In some implementations, the operation mode state is retained for the period of time, but may be erased upon certain events such as, for example, the removal of the battery pack from the power tool. If there is no operation mode state stored in the memory module  63 , then a default operation mode is entered, where the default operation mode may be a triggered operated mode such as, for example, the manual high speed operation mode. 
     In some implementations, the memory module  63  retains state information for the operation mode. In some implementations, the memory module in the motor controller may maintain state information for the operation mode. 
     In some implementations, process  2900  may not default to the last operation mode as stored in the memory module  63  and instead may use a default operation mode, where the default operation mode may be one of the trigger operated modes such as, for example, the manual high speed mode or the manual low speed mode. 
     Process  2900  determines whether an input was received from the electronic mode select switch ( 2904 ). For example, the power tool  10  determines if the user has selected the electronic mode select switch  60 . If an input from the electronic mode select switch  60  is received, then the operation mode of the power tool  10  is changed ( 2906 ). The selected mode may be stored in the memory module  63  and/or in a memory module in the motor controller. Then, process  2900  loops back and determines again if an input from the electronic mode select switch has been received ( 2904 ). In this manner, a user may cycle through and select a desired operation mode for the power tool  10 , as described above in more detail. 
     If an input from the electronic mode select switch  60  is not received or is not received again, then the power tool  10  determines if an input is received from the nosepiece switch ( 2908 ). As discussed above, the nosepiece switch may be a part of the sensor assembly  78 , which is activated when the user presses the power tool  10  against a workpiece. If there is an input from the nosepiece switch and the auto start mode is selected ( 2910 ), then the auto start mode operation is performed ( 2912 ). 
     If there is no input received from the nosepiece switch ( 2908 ) or the auto start mode is not detected ( 2910 ), then process  2900  determines whether an input has been received from the power switch  30  ( 2914 ). If no input is received from the power switch  30 , then process  2900  goes back to determine whether an input is received from the electronic mode select switch  60  ( 2904 ). If an input is received from the power switch  30 , then the power tool  10  determines which operation mode is selected ( 2916 ). The microcontroller  62  in the electronic mode select switch  60  may be programmed to determine the operation mode ( 2916 ) and retrieve the selected mode from storage in the memory module  63  and/or the motor controller. 
     Depending on the selected operation mode  2916 , power is delivered to the motor in one of the trigger operated mode ( 2918 ), the lock on mode ( 2020 ), or the auto start mode ( 2012 ). 
     Referring to  FIG. 29B , the trigger operated mode routine  2918  is illustrated. When the power switch  30  is activated and the power tool  10  is in the trigger operated mode, then power is delivered to the motor ( 2930 ). As long as the power switch  30  is activated ( 2932 ), power is delivered to the motor ( 2930 ). When the power switch  30  is released or deactivated, then power is discontinued to the motor ( 2934 ) and the process returns ( 2936 ) to  FIG. 29A  at step  2904  to determine whether an input is received from the electronic mode select switch  60 . 
     The tiggered operated mode may include a manual high speed mode, a manual low speed mode, or a variable speed mode. In the manual high speed mode, the motor is controlled to rotate at a substantially constant high speed (or substantially constant high target speed) regardless of the travel distance of the power switch. In the manual low speed mode, the motor is controlled to rotate at a substantially constant low speed (or substantially constant low target speed) regardless of the travel distance of the power switch. In the variable speed mode, the speed of the motor depends on the travel distance of the power switch. Additional details for these modes of operation are described above. 
     Referring to  FIG. 29C , the lock on mode routine  2920  is illustrated. When the lock on mode has been selected, continuous power is delivered to the motor ( 2940 ) starting when the power switch is activated. At the same time a timer is started if a timer is not currently running. Continuous power continues to be delivered to the motor without interruption, even if the power switch is subsequently released. Power continues to be delivered to the motor ( 2940 ) until the power switch is subsequently actuated and released a second time (step  2942 ) or until a timer expires (step  2943 ), whichever comes first. Once the power switch is activated and released a second time ( 2942 ) or the timer expires ( 2943 ), then power to the motor is discontinued ( 2944 ) and the process returns ( 2946 ) to  FIG. 29A  at step  2904  to determine whether an input is received from the electronic mode select switch. 
     Referring to  FIG. 29D , the auto start mode routine  2912  is illustrated. When the auto start mode has been selected, power is delivered to the motor ( 2950 ). As long as the motor start switch is activated ( 2952 ), power is delivered to the motor ( 2950 ). The motor start switch may be one or both of the power switch  30  and the nosepiece switch, which is part of the sensor assembly  78 . That is, power may be delivered to the motor in the auto start mode using one or both of the power switch  30  and the nosepiece switch. Once the motor start switch is released or no longer activated ( 2953 ), then power to the motor is discontinued ( 2954 ) and the process returns ( 2956 ) to  FIG. 29A  at step  2904  to determine whether an input is received from the electronic mode select switch. 
     It is understood that the elements of process  2900  may be performed in a different order than the order illustrated in  FIG. 29A . 
     In the following some examples are described. 
     Example 1: A power tool comprising: 
     a housing; 
     a motor disposed in the housing; 
     a motor controller disposed in the housing and electrically coupled to the motor; 
     a transmission disposed in the housing and coupled to the motor; 
     a tool bit holder configured to be rotatably driven by the motor via the transmission and configured to receive a tool bit for rotatably driving threaded fasteners; 
     a power switch actuatable from outside the housing and coupled to the motor controller to control power delivery to the motor; and 
     an electronic mode select switch actuatable from outside the housing and electrically coupled to the motor controller, the electronic mode select switch configured to select between at least a first mode of operation in which power delivery to the motor is controlled by actuation of the power switch and an electronic lock on mode in which continuous power is delivered to the motor upon a single actuation and release of the power switch. 
     Example 2: A power tool comprising: 
     a housing including a motor housing portion, a transmission housing portion coupled to the motor housing portion, and a handle portion coupled to and extending transverse to the motor housing portion; 
     a motor disposed at least partially in the motor housing portion; 
     a motor controller disposed in the housing and electrically coupled to the motor to control power delivery to the motor; 
     a transmission disposed at least partially in the transmission housing portion; 
     a tool bit holder configured to be rotatably driven by the motor via the transmission and configured to receive a tool bit for rotatably driving threaded fasteners; 
     a power switch actuatable from outside the housing and coupled to the motor controller to control power delivery to the motor; and 
     an electronic mode select switch coupled to and actuatable from outside the motor housing, the electronic mode select switch electrically coupled to the motor controller and configured to select among a plurality of modes of operation of the motor, 
     wherein the electronic mode select switch is configured to be actuatable by a user with one hand while gripping the housing with the one hand in a position for actuating the power switch and driving a threaded fastener into a workpiece. 
     Example 3: A power tool comprising: 
     a housing including a motor housing portion, a transmission housing portion coupled to the motor housing portion, and a handle portion coupled to and extending transverse to a bottom surface of the motor housing portion, the motor housing portion including a top surface generally opposite the bottom surface; 
     a motor at least partially disposed in the motor housing portion; 
     a motor controller disposed in the housing and electrically coupled to the motor; 
     a transmission disposed at least partially in the transmission housing portion; 
     a tool bit holder configured to be rotatably driven by the motor via the transmission and configured to receive a tool bit for rotatably driving treaded fasteners; 
     a power switch actuatable from outside the housing and coupled to the motor controller to control power delivery to the motor; 
     an electronic mode select switch coupled to and actuatable from outside the motor housing portion, the electronic mode select switch electrically coupled to the motor controller and configured to select among a plurality of modes of operation of the motor, the electronic mode select switch disposed on the top surface of the motor housing portion; and 
     a belt clip disposed on the top surface of the motor housing portion. 
     Example 4: A power tool comprising: 
     a housing; 
     a motor disposed in the housing; 
     a motor controller disposed in the housing and electrically coupled to the motor; 
     a transmission and clutch assembly disposed in the housing and coupled to the motor, the transmission and clutch assembly including at least an output clutch and an input clutch; 
     a tool bit holder configured to be rotatably driven by the motor via the transmission and clutch assembly and configured to receive a tool bit for rotatably driving threaded fasteners; 
     a power switch actuatable from outside the housing and coupled to the motor controller to control power delivery to the motor; 
     an electronic mode select switch actuatable from outside the housing and electrically coupled to the motor controller and having one or more modes of operation for controlling power to the motor; and 
     a mode change sensor for sensing changes in position of the output clutch, the mode change sensor located forward of the input clutch and configured to send signals to the electronic mode select switch responsive to sensing changes in the position of the output clutch. 
     Example 5: A power tool comprising: 
     a housing; 
     a motor disposed in the housing; 
     a motor controller disposed in the housing and electrically coupled to the motor; 
     a transmission and clutch assembly disposed in the housing and coupled to the motor, the transmission and clutch assembly including a planetary gear assembly having a planet carrier, an output clutch, an intermediate clutch coupled to one face of the planet carrier, and an input clutch integrated with an opposite face of the planet carrier; 
     an electronic mode select switch coupled to and actuatable from outside the motor housing, the electronic mode select switch electrically coupled to the motor controller and configured to select among a plurality of modes of operation of the motor; and 
     a tool bit holder configured to be rotatably driven by the motor via the transmission and clutch assembly and configured to receive a tool bit for rotatably driving threaded fasteners. 
     Example 6: A power tool comprising: 
     a housing; 
     a motor disposed in the housing; 
     a motor controller disposed in the housing and electrically coupled to the motor; 
     a transmission disposed in the housing and configured to be driven by the motor; 
     an output spindle extending from the housing and configured to be moved axially relative to the housing when depressed against a workpiece; 
     a clutch disposed between the transmission and the tool bit holder, the clutch having an input clutch member coupled to the transmission and an output clutch member coupled to the output spindle, the output clutch moveable between a rearward position in which torque is transmitted from the transmission to the output spindle via the clutch when the output spindle is depressed against a workpiece, and a forward position in which torque transmission from the transmission to the output shaft is interrupted; 
     a sensor assembly including a sensed member coupled to the output spindle axially forward of the output clutch member and configured to move axially with the output spindle and a sensing member axially fixed relative to the housing to sense a position of the sensed member; and 
     a brake mechanism configured to engage the output member the clutch when in the forward position to inhibit rotation of the output member, the brake mechanism including at least one leg extending from a point axially forward of the sensed member and extending past at least a portion of the sensed member to engage the output clutch member when in the forward position. 
     Example 7: The power tool as in any of the preceding examples, wherein the power tool is a screwgun. 
     As used herein, the singular forms “a,” “an,” and “the” may be intended to include the plural forms as well, unless the context clearly indicates otherwise. The terms “comprises,” “comprising,” “including,” and “having,” are inclusive and therefore specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
     When an element or layer is referred to as being “on,” “engaged to,” “connected to,” or “coupled to” another element or layer, it may be directly on, engaged, connected or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly engaged to,” “directly connected to,” or “directly coupled to” another element or layer, there may be no intervening elements or layers present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between,” “adjacent” versus “directly adjacent,” etc.). As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms may be only used to distinguish one element, component, region, layer or section from another region, layer or section. Terms such as “first,” “second,” and other numerical terms when used herein do not imply a sequence or order unless clearly indicated by the context. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the example embodiments. 
     Terms of degree such as “generally,” “substantially,” “approximately,” and “about” may be used herein when describing the relative positions, sizes, dimensions, or values of various elements, components, regions, layers and/or sections. These terms mean that such relative positions, sizes, dimensions, or values are within the defined range or comparison (e.g., equal or close to equal) with sufficient precision as would be understood by one of ordinary skill in the art in the context of the various elements, components, regions, layers and/or sections being described. 
     While certain features of the described implementations have been illustrated as described herein, many modifications, substitutions, changes and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the scope of the embodiments.