Abstract:
A new log support and clamp system (log rest) for a portable sawmill, having a log rest and a log dog. The log rest features a rack and pinion for adjusting a vertical position of the log rest using an actuation mechanism located on the operator&#39;s side of the portable sawmill, which improves the ability of the user to affix the log in place for sawing. Also, a portable sawmill having such a log rest.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of and priority to Canadian Patent Application No. 2,806,456 filed Jan. 24, 2013, under the title LOG REST WITH RACK AND PINION SYSTEM. 
     The content of the above patent application is hereby expressly incorporated by reference into the detailed description hereof. 
     FIELD OF THE INVENTION 
     The present invention relates to a new log support system (log rest) for a portable sawmill. The log rest features a rack and pinion mechanism which improves the ability of the user to raise and lower the log rest from the operator&#39;s side of the portable sawmill. 
     BACKGROUND OF THE INVENTION 
     There are several prior inventions for portable sawmills. 
     U.S. Pat. No. 5,784,941 describes a portable sawmill in which the functions of adjusting a cut and making a cut are divided between two separate devices. The invention discloses a vertical chain saw, ideally operated in an upward direction. The patent also discloses a log restraint system comprising a setwork having a headstock and a lockable L-shaped log dog, joined by a clamp which is locked with a lever. 
     U.S. Pat. No. 5,243,892 discloses a portable sawmill with a frame base and an inverted U-shaped frame, supported by a carriage rolling along side tracks defined by the frame base. In use, the log is placed on the U-shaped frame and clamped with a tubular clamp held within a sleeve and locked in place using threaded blocks. 
     U.S. Pat. No. 4,640,170 discloses a portable saw mill with a frame that surrounds the log. The frame is dragged or slid along a frame supporting surface. The frame holds a chain saw at the two ends of its blade, in horizontal fashion, with chain saw support members. The invention uses sliding means for facilitating the movement of the frame over the log. The log is secured against rolling using a simple jig or similar means. 
     U.S. Pat. No. 4,275,632 describes a portable sawmill comprising a U-shaped support or carriage, holding a band saw. When in use, a log is placed between the two guide rails and is supported in place by appropriately distanced log supports. 
     U.S. Pat. No. 4,307,641 describes a portable sawmill comprising two skid rails, vertical support members, a pair of guide rails. The log is held in place by two externally threaded log screw pins with pointed ends. 
     U.S. Pat. No. 4,300,428 describes a portable sawmill having a frame, a guide member mounted above the frame, and a carriage. The chain saw is mounted above the log, and operates at about a 45 degree angle to the horizontal. The log is held in place with log dogs which are adapted for hooking the log and holding it in position. 
     U.S. Pat. No. 4,235,140 describes a saw mill. The logs are held in place with a standard log dog attached to the cross members on which the log is placed. 
     U.S. Pat. No. 3,965,788 describes a saw guide for use with a vertically operated portable chain saw. The saw guide apparatus is attached directly to the log. 
     U.S. Pat. No. 3,926,086 describes a portable saw mill that uses a complex pulley system to move the chain saw and supporting platform. When in use, a log is placed, and clamped, between the guide rails, using a set of circular discs eccentrically oriented on a rod. 
     U.S. Pat. No. 3,695,316 describes a portable timber milling jig that uses a carriage, holding a chain saw, axially surrounding a square guide rail. The chain saw is held at an approximately 45 degree angle and only uses one guide rail, and utilizes ball bearings on the carriage to move the carriage with respect to the guide rail. When in use, a log is placed under the guide rail, and fixed using clamping points driven into the center of the log, to which support clamps are fastened. 
     Canadian Patent No. 1,200,180 describes a portable saw mill comprising a frame with a guide rail and a carriage moveable along the guide rail. A band saw is supported by the carriage. The carriage is moveable along the guide rail along two sets of wheels, one engaged with the upper side of the guide rail and the other with the lower side. The log is held in place by its own weight, or by stops and a traditional locking dog. 
     U.S. Pat. No. 4,245,535 describes a portable sawmill with an elaborate hydraulic apparatus for cutting a log. The chain saw cuts in a vertical motion. The log is held in place using a log holding assembly having a toothed prod which grips the outer end of the log, and a cylinder which impales the inner end of the log with a ram, forcing the outer end against the prod. 
     U.S. Pat. No. 4,210,049 describes an “x” frame for holding a log, with a chain saw affixed to the frame in cantilever position for cutting logs crosswise. The log is held in the nook of the “x” frame. 
     Canadian patent application 2,541,734 describes a portable sawmill that is easily displaceable, easily assembled and disassembled into portable components, and which can use generic components as its saw and/or guide rails. The log is held in place using traditional log dogs. 
     Canadian patent application 2,687,623 describes a log support system (log rest) for a portable sawmill. The log rest features a ratcheting, adjustable clamp which allows a user to affix the log in place for sawing. To lower the log rest, a pawl is disengaged from the log, the log rest is manually lowered, and the pawl is re-engaged. 
     In all cases, the log rest is on the opposite side of the log from the log dog. Accordingly, when the sawmill bed is wide, two operators are required to adjust the log rest and log dog, or the operator must lean over the bed and log (which can inconvenient, if not dangerous), or the operator must walk around the log. Leaning over also strains the back. Walking around is time consuming. As the log rest and log dog must be lowered as the top of the log is removed by cuts, this task must be repeated multiple times. 
     SUMMARY OF THE INVENTION 
     The present invention provides a log support and clamp assembly for use in a portable sawmill, comprising a horizontal support beam having two ends for affixing to a sawmill. A log dog having a vertical portion generally perpendicular to said horizontal support beam and extending upwards therefrom, and a top end having a pick protruding therefrom. A log rest assembly having a clamp housing affixed to said support beam and horizontally displaceable thereto, a post connected to or housed within said clamp housing, said post configured in a generally vertical direction and said clamp housing having a rack and pinion mechanism for raising the post relative to the horizontal support beam. 
     In one embodiment, the rack and pinion mechanism includes a tensioned chain attached to the log rest assembly, and a ratcheted wheel attached to the clamp housing for engaging teeth on the tensioned chain. 
     In an embodiment, the log support and clamp assembly further includes an actuation mechanism having a second ratcheted wheel attached at one side of the sawmill opposite of the log rest assembly; a rotatable shaft extending between the sides of a sawmill for connecting the ratcheted wheel to the second ratcheted wheel; and a handle attached to the second ratcheted wheel for actuating the ratcheted wheel. Rotation of the handle causes the ratcheted wheel to traverse the chain, thereby raising or lowering the vertical position of the post. For example, the handle may be rotated in a clockwise direction to lower the vertical position of the post and may be rotated in a counterclockwise direction to raise the vertical position of the post. 
     In an embodiment, the log support and clamp assembly includes a pawl having a tooth for engagement with a notch of the second ratcheted wheel, where the pawl locks the vertical position of the post. 
     In one embodiment, the log support and clamp assembly can be in an unlocked position, the log dog horizontally displaceable along the horizontal support beam, and in a locked position, the log dog horizontally non-displaceable along the horizontal support beam. In another embodiment, in an unlocked position, the log dog is vertically displaceable relative to the horizontal support beam, and in a locked position, the log dog is vertically non-displaceable relative to the horizontal support beam. 
     Optionally, the log dog has a log dog handle extending at an upwards angle from the top end. There are many forms of log dogs which can be used in association with the present invention. 
     The present invention also teaches a portable sawmill comprising the log support and clamp assembly, as well as a kit for retrofitting a log support and clamp assembly to a portable sawmill. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a front perspective view of the log support/clamping system of the present application. 
         FIG. 2  shows a rear perspective view of the log dog of  FIG. 1 . 
         FIG. 3  shows a sectional front perspective view of the log rest having a rack and pinion mechanism of  FIG. 1 . 
         FIG. 4  shows a sectional side perspective view of the actuation mechanism for the log rest of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention provides a simple, versatile, cost-effective and portable log support system for a sawmill such as a portable sawmill. The system provides exemplary fixing of the log onto the mill bed, and allows for a user to clamp the log in place utilizing only one hand and from the operator&#39;s side of the portable sawmill. This permits the user to use the other hand to stabilize the log until the log rest is moved into the desired position using the rack and pinion mechanism, and the log clamped between the log rest and the log dog, a cam-operated clamp that squeezes the log. The log rest is thus the back-stop against which the log is secured and against which the log dog exerts force, thereby clamping the log. The log rest thus can be quickly raised or lowered to suit the height of the log being milled. The log rest is raised or lowered by turning a handle at the operator&#39;s side of the portable sawmill, and the log rest locks in place with a pawl located at the other side of the portable sawmill. The log rest can lock automatically (e.g. by spring activation), or can be manually locked into position. Thus, both the log rest operating mechanism and the log dog are located at the operator&#39;s side of the mill bed. 
     The log rest is particularly suitable for portable sawmills, and for use by mill operators, particularly those working on their own without assistance. It allows for a highly variable log size to be affixed to it, and it allows for a single operator to maneuver the log into place, then clamp the log in place using only one hand to actuate the rack and pinion mechanism by a handle located at the operator&#39;s side of the portable sawmill. This allows the user to utilize their other hand to stabilize the log, greatly improving use and safety of a sawmill, for example, when a single person, in a remote area, is sawing logs. The log rest also allows great flexibility in the size of logs being clamped to it, thanks to its highly adjustable nature. Notably, the log rest can be adjusted to a rough log sizing, then fine adjusted for each individual log in an easy, one-handed manner. The operator, using only one hand and staying on the operator&#39;s side of the portable sawmill, can raise or lower the log rest to suit the log size by releasing the pawl and turning a handle, actuating the rack and pinion mechanism. The log rest may be locked in place using the pawl located on the operator&#39;s side of the portable sawmill. 
     The log rest design enables it to be sold as part of a sawmill such as a portable saw mill, or as a separate item for retrofitting onto an existing sawmill, for example, as a kit or an accessory option. The log rest can be manufactured from sturdy, reasonably inexpensive materials, and permits a high level of configurability for different size logs. 
     An embodiment of the present invention will now be described as shown in  FIGS. 1-4 . 
     As shown in  FIG. 1 , the log support system comprises a support beam  52  designed to be affixed to a sawmill (not shown) between sawmill bed rails  101 ,  102  using sawmill brackets  70 ,  74 . The sawmill brackets  70 ,  74  may also be part of sawmill rails  101 ,  102 . Attached to support beam  52  are log dog  48  and log rest  54 . The design is such that the sawmill brackets  70 ,  74  can be affixed to opposing sides of the sawmill rails  101 ,  102  by screwing them thereto utilizing screw holes  78 . As shown in  FIGS. 1 and 2 , log dog  48  and log rest  54  may then be easily affixed to or removed from the sawmill rails  101 ,  102  through removal of sawmill bracket pin  72  shown, lateral displacement of the support beam  52  through sawmill support opening  84  in bracket  70 , then displacement of the log dog  48  and log rest  54  beyond the end of support beam  52 . 
     As seen in  FIGS. 1 and 2 , log dog  48  is removably affixed to the support beam  52 , through housing front  56  and back  86  which together receive vertical portion  92 . Vertical portion  92  comprises pick  46  and log support  50  (may also be referred to as log dog handle) at its top end, pin limiters  60  at its bottom end, and adjustment apertures  82  extending vertically therebetween. Apertures  82  lighten the weight of the log dog  48 . Housing  56  allows vertical displacement of vertical portion  92  in relation to housing  56 ,  86  and therefore support beam  52 . As seen in  FIG. 2 , housing  86  allows horizontal displacement of log dog  48  in relation to support beam  52 , when housing screw  88  is loosened. Vertical portion  92  can thus be displaced vertically within adjustment apertures  82 , and can be displaced horizontally, along with housing  56 ,  86 , along support beam  52 . When housing screw  88  is tightened, housing  86  forms a clamp which affixes the log dog  48  in a horizontal position relative to support beam  52 , limiting horizontal displacement relative to support beam  52 . A second housing screw (not shown) secures log dog  48  in a desired vertical position relative to support beam  52 . Alternatively pin limiters (e.g.  60 ) can secure log dog  48  in a desired vertical position. 
     Log dog  48  can be removed from support beam  52 , by removing pin limiters ( 62 ,  64 ) located at the bottom of the log dog  48 , and lifting vertical portion  92  out of housing  56 ,  86 . Log dog  48 , along with housing  56 ,  86 , can also be removed from support beam  52  by removing support beam  52  from sawmill bracket  70  as described above and displacing vertical portion  92  horizontally beyond the end of support beam  52 . 
     Typically, log dog  48  is adjusted horizontally and vertically in relation to support beam  52  each time a log is clamped. The horizontal and vertical positioning will depend on the size of the logs to be cut. For example, for larger logs, log dog  48  will typically have a horizontal location on support beam  52  that is closer to sawmill bracket  70 , as compared to its positioning for smaller logs. With large logs, both log dog and log rest will each be as far apart from each other and, as close to their respective sawmill rails  101 ,  102 . Vertical displacement will be such that pick  46  will be further away from support beam  52  for larger logs as compared to smaller logs. Once log dog  48  is adjusted for use, finer adjustments for each particular log, and clamping the log can be performed using log rest  54 . Typically, the user adjusts the log rest, then the log dog. Either or both may require finer adjustment. The log dog  48  freely slides vertically and horizontally. Each time a log is clamped, adjustments are made on both planes. The adjustment made to the log rest  54  is independent of those made with the log dog. As explained in more detail below, an operator first adjusts the log rest  54  and then adjusts the log dog  48  and clamp. The primary similarity in the adjustments made to both the log dog and log rest is that their vertical displacement is dependant on log size. 
     As seen in  FIG. 3 , log rest  54  comprises log rest housing  32  which is affixed to support beam  52 . Log rest housing  32  comprises clamp housing lock (not shown) which enables the log rest housing  32  (and thus log rest  54 ) to be affixed to the support beam  52 . Loosening a clamp housing lock (not shown) allows the log rest housing  32  (and thus the entire log rest  54 ) to be horizontally displaced along support beam  52 . 
     As seen in  FIGS. 1 and 3 , log rest housing  32  houses post  36  which can be vertically displaced relative to log rest housing  32  utilizing ratcheting means. 
     Note that clamp housing lock does not affect vertical displacement of post  36 . Post  36  comprises wheel  40  at its top end, which has a rigid cuff  42 . Attached to the rigid cuff  42  is connection  120  and pin  122 , to secure the wheel  40  to the rigid cuff  42 . As well, the connection  120  extends in one direction to an end  124 . The end  124  of the connection  120  is attached to a securing connection  130 . The bottom of the post  36  also has a securing plate  136  which extends out from the post  36 . A chain  105  is attached or integrally formed at a top end to the securing connection  130 , and the bottom end of the chain  105  is attached to the securing plate  136  of the post  36 . The chain  105  is tensioned on both the top end and the bottom end to act as a rack. Alternatives to the chain  105  can be used, such as a stamped or cut metal rack with teeth. 
     As seen in  FIG. 3 , the chain  105  works with a pinion or ratcheted wheel  106 . More particularly, the teeth of the ratcheted wheel  106  mesh or engage with teeth on the chain  105 . Log rest housing  32  has support plate  115 , and the ratcheted wheel  106  is mounted to the support plate  115 . The ratcheted wheel  106  is connected to a shaft  107  via a universal joint  108 . The shaft  107  may be extendable to vary its length depending on the width between sawmill rails  101 ,  102 . The universal joint  108  includes a pair of hinges  110 ,  112  located close together and oriented at ninety degrees to each other. As well, the universal joint  108  includes a central cube component  114  that connects the pair of hinges  110 ,  112 . In another embodiment, the pair of hinges  110 ,  112  may be connected using a cross shaft (not shown). Bolts  116 ,  117  secure the hinges  110 , 112  to the central cube component  114 . The universal joint  108  permits the shaft  107  to rotate and hinge as required during actuation of the ratcheted wheel  106  traversing the chain  105 . 
     As seen in  FIG. 4 , the shaft  107  is connected at a second end to a second ratcheted wheel  230  (on the opposite side of the sawmill, i.e. the side of rail  102 ) via a second universal joint  200  located at the operator&#39;s side of the sawmill. The second universal joint  200  includes a pair of hinges  202 ,  204  connected by a central cube component  206 . The pair of hinges  202 , 204  are secured to the central cube component  206  via a pair of bolts  208 ,  210 . 
     The second ratcheted wheel  230  is mounted to an L-shaped bracket connection  220 . A first side  221  of the bracket connection  220  is attached to the bottom of rail  102 , with a second side  222  of the bracket connection  220  extending down from the exterior edge of rail  102 . The second ratcheted wheel  230  is mounted to the exterior face  223  of the second side  222  which is on the operator&#39;s side of the sawmill. Also on the operator&#39;s side, there is a handle plate  226  that is connected to the second ratcheted wheel  230  via a cylindrical shaft  232 . One or more handles  227 , 228  are attached to the handle plate  226 . The cylindrical shaft  232  passes through an opening on the bracket connection  220  and attaches to a bushing  213  on the interior side  224  of the second side  222  of the bracket connection  220 . A connection component  212  secures the bushing  213  to the second universal joint  200  using a bolt  214  and nut  215 . 
     A pawl  240  is secured to the exterior face  223  of the second side  222  of the bracket connection  220  using a bolt  241  and washer  242 . The pawl  240  has a ratchet tooth  245  that is adapted to fit into a notch of the second ratcheted wheel  230 . As well, the pawl  240  has pawl handle  250  that may be used to move the pawl  240  from a first position to lock the second ratcheted wheel  230  in place, to a second position which removes the ratchet tooth  245  from a notch of the second ratcheted wheel  230 . The pawl  240  may be used to lock the second ratcheted wheel  230  in place, and thereby locking the vertical position of the log rest housing  32  along post  36  by arresting the rotational movement of  107 . In a preferred embodiment, the pawl and notches are configured to allow free movement of the rack and pinion in an upwards, counterclockwise motion, when the pawl is unlocked. 
     Handles  227 , 228  and pawl  240  thus allow the operator to move the post  36  up or down by releasing the pawl  240  and by rotating the handles  227 ,  228 . The post  36  may be locked in the selected position by returning the pawl  240  to its engaged position. In operation, the handles  227 , 228  are rotated to turn the second ratcheted wheel  230  and the cylindrical shaft  232 , which rotates the shaft  107  and thereby actuates the ratcheted wheel  106  to move the ratcheted wheel  106  up or down the chain  105 , resulting in movement of the post  36  up or down relative to the log rest housing  32 . The handles  227 , 228  may be rotated in a clockwise direction to actuate the ratcheted wheel  106  up the chain  105  to lower the vertical position of the post  36 . As well, the handles  227 , 228  may be rotated in a counterclockwise direction to actuate the ratcheted wheel  106  down the chain  105  to raise the vertical position of the post  36 . 
     Post  36  may comprise horizontal adjustment bolt (not shown), which allows for fine tuning of the horizontal location of post  36  relative to support beam  52 , even while log rest housing  32  is secured and horizontally affixed to support beam  52 . As previously discussed, the lower end of post  36  also comprises the securing plate  136  which prevents the post  36  from so much vertical displacement that it is inadvertently removed out of the top of log rest housing  32 . 
     The log rest is used as follows. The horizontal and vertical location of log dog  48  relative to support beam  52 , and the horizontal position of log rest  54  relative to support beam  52  are set to a desired position, based on the size of the logs to be milled. The position is estimated by the user such that the diameter of the log is slightly larger than the distance between the log dog  48  and the log rest  54 . The post  36  is set at its lowest position by releasing the pawl  240  using pawl handle  250  and rotating the handles  227 , 228  to actuate the ratcheted wheel  106  to traverse up the chain  105 . The log is placed, pushed, or rolled against the log rest. Log dog handle  50  is configured such that a downward force on it causes a cam or apertures  82  inside to be forced against the pick  46  which, in turn, is pressed into the log. The log is rolled onto the log deck, and rests on the cross bunks (spans between the rails). It is positioned into the area between the log rest  54  and the log dog  48 . The user then displaces the post  36  upwards, using the rack and pinion mechanism actuated by handles  227 , 228  such that the log rest  54  supports the log but is lower than the path along which the blade will travel. Once post  36  is adjusted for correct height, the operator pushes the log against post  36 , vertically and horizontally adjusts vertical portion  92 , lifts handle  50 , pushes log dog  48  against the log, lowers handle  50 , thereby forcing pick  46  into the log. This allows for clamping of the log between the log dog  48  and the log rest  54 . As the clamping gets tighter, pick  46  digs into the side of the log, providing more stability. In this manner, utilizing handles  227 , 228 , a user is able to clamp the log between the post  36  and the pick  46  utilizing one hand and while remaining on the operator&#39;s side of the sawmill. Log rest housing  32  also comprises square block surface  38 , which provides support for post  36  as post  36  presses against the log. 
     It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims. 
     TABLE OF ELEMENTS 
     
         
           32  Log rest housing 
           36  Post 
           38  Square block surface 
           40  wheel 
           42  rigid cuff 
           46  pick 
           48  log dog 
           50  log dog handle or log support 
           52  support beam 
           54  log rest 
           56  housing front 
           60  pin limiter 
           70  sawmill bracket 
           72  sawmill bracket pin 
           74  sawmill bracket 
           78  screw holes 
           82  apertures 
           84  sawmill support opening 
           86  housing back 
           88  housing screw 
           92  vertical portion of log dog 
           101  sawmill rail 
           102  sawmill rail 
           105  chain 
           106  pinion or ratcheted wheel 
           107  shaft 
           108  universal joint 
           110  hinge 
           112  hinge 
           115  support plate 
           116 ,  117  Bolts 
           120  connection 
           122  pin 
           124  end of connection component 
           130  securing connection 
           136  securing plate 
           200  second universal joint 
           202  hinge 
           204  hinge 
           206  central cube component 
           208  bolt 
           210  bolt 
           213  bushing 
           214  bolt 
           215  nut 
           220  L-shaped bracket connection 
           221  first side of bracket connection 
           222  second side of bracket connection 
           223  exterior face of second side 
           224  interior face of second side 
           226  handle plate 
           227  handle 
           228  handle 
           230  second ratcheted wheel 
           232  cylindrical shaft 
           240  pawl 
           241  bolt 
           242  washer 
           245  ratchet tooth 
           250  pawl handle