# Patent

## Title
Router height adjustment apparatus

## Abstract

A router depth adjustment mechanism for minimizing rapid course depth adjustment for standard and plunge routers. Routers with rapid or course adjustment mechanisms may permit a router motor housing to drop suddenly, if the user is inattentive. Sudden adjustments may result in damage to the router and potentially contact the user. The mechanism of the present invention includes a threaded shaft and a biased thread engaging member which may be disengaged for rapid adjustment. A restraining device and/or a break may be included to minimize the rate of change.

## Background
CROSS REFERENCE
The present application is a Divisional application and Claims priority under 35 U.S.C. §121 to U.S. patent application Ser. No. 10/292,171, entitled: Router Height Adjustment Apparatus, filed on Nov. 12, 2002, now U.S. Pat. No. 6,986,369, which is hereby incorporated by reference in its entirety


FIELD OF THE INVENTION
The present invention relates to the field of hand tools and particularly to an apparatus for minimizing rapid height adjustment.
BACKGROUND OF THE INVENTION
Cautious operation is important when utilizing power tools, such as a router. Power tool manufactures strive to develop tools which minimize user risk. For example, some router depth adjustment mechanisms allow a router motor housing to adjust rapidly, which may damage the device.
For instance, United States Published Patent Application 2002/0043294 A1, entitled: Router, which is hereby incorporated by reference in its entirety, describes a device which permits rapid depth adjustment. While such a device provides the ability to adjust rapidly, rapid adjustment may result in pinching and/or damage to the router itself. For example, when an unwary user replaces the motor housing into the router base, such as after changing a bit, the motor housing and motor may drop upon utilizing a course adjustment device, if the motor housing is not grasped.
Furthermore, if a user is forced to support the motor housing, such as to prevent damage to the router when adjusting plunge depth, the user's grasping hand or fingers may be smashed and/or pinched, upon rapid depth adjustment, due to the weight of the router motor and housing.
Moreover, routers which include grasping apparatus for aiding in grasping the base or motor housing typically include a lip or rim for at least partially supporting the weight of the router during operation and transfer. Problems may occur if the motor housing and grasping apparatus interact to create a pinch point where a user's finger or hand may be caught.
Moreover, the router itself may become damaged, such as when an adjustment mechanism is released when the router is implemented with a router table. For instance, if a user actuates the course adjustment device, the router may drop suddenly.
Therefore, it would be desirable to provide an apparatus for promoting router height adjustment.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to an apparatus for promoting efficient router depth adjustment. As will be appreciated by those of skill in the art, the apparatus of the present invention may be implemented in rotary cut-off tools, both standard and plunge routers, and the like.
In a first aspect of the present invention, a router includes a motor housing, a base, an adjustment mechanism and a hand grip attachment. The adjustment mechanism includes a shaft with a threaded portion and a thread engaging member. The shaft is attached to the motor housing and is received in the base wherein the engaging member may selectively engage the threaded portion. The hand grip includes a lip for at least partially supporting the router when grasped. The lip extends generally outward from the base to which it is attached. The lip may be disposed even with or below the end of the base adjacent to the motor housing so as to minimize potential contact with the user.
In an additional aspect of the invention, a router adjustment device includes a base, a motor housing, a frictional zone, and an adjustment mechanism including a shaft and threaded engaging member. The motor housing may adjustably secure within the base for permitting depth adjustment. The frictional zone may be disposed either on the base or motor housing. For instance, the frictional zone is disposed generally at the interface of the motor housing and base. The frictional zone at least partially resists the movement of the motor housing, such as when the thread engaging member is disengaged from the threaded shaft.
In a further aspect of the invention, an apparatus for controlling router adjustment includes a base, a motor housing, and an adjustment mechanism. The adjustment mechanism includes a shaft, a threaded engaging member and means for at least partially restraining the motor housing from moving with respect to the base. For instance, the adjustment mechanism contains a spring for generally biasing the shaft to prevent damage to the router.
In another aspect of the invention, a router adjustment device includes a base, a motor housing, an adjustment mechanism, and a brake element. The motor housing is adjustably secured in the base to permit longitudinal movement. The break element is disposed in the base substantially perpendicular to the motor housing. The break element may be activated to at least partially resist the movement of the motor housing, such as when a course adjust occurs.
It is to be understood that both the forgoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention and together with the general description, serve to explain the principles of the invention.



BRIEF DESCRIPTION OF THE DRAWINGS
The numerous advantages of the present invention may be better understood by those skilled in the art by reference to the accompanying figures in which:
FIG. 1 is an isometric view of a router including hand grip attachment with a support lip terminating generally even with the end of a base;
FIG. 2 is an exploded view of a router with a motor housing including an angled portion, for minimizing pinching, adjacent to a base;
FIG. 3 is an exploded view of a router with a motor housing including an angled portion, for minimizing pinching, adjacent to a base and FIG. 3A is a top view of the base of the router of FIG. 3A;
FIG. 4A is a cut away view of an apparatus for controlling router adjustment including a compression spring for minimizing rapid adjustment;
FIG. 4B is a cut away view of an apparatus for controlling router adjustment including a coiled spring with lever arm for minimizing rapid adjustment;
FIG. 4C is a cut away view of an apparatus for controlling router adjustment including a gasket for minimizing rapid adjustment;
FIG. 4D is a cut away view of an apparatus for controlling router adjustment including a frictional zone mounted to a thread engaging member for minimizing rapid adjustment;
FIG. 5A is cross sectional view of a router adjustment device including a biased breaking element;
FIG. 5B is cross sectional view of a router adjustment device including a biased breaking element capable of automatic actuation by a thread engaging member; and
FIG. 5C is cross sectional view of a router adjustment device including a thread engaging member with a contact zone for minimizing rapid course depth adjustment.



DETAILED DESCRIPTION OF THE INVENTION
Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings.
Referring generally now to FIGS. 1 through 5C, exemplary embodiments of the present invention are shown.
Referring to FIG. 1, a router 100 is shown. A base 102 and motor housing 104 are included in the router 100. The base 104 is suitable for supporting the router 100 when the motor housing 104 is upwardly directed. The base 102 adjustably secures the motor housing 104. For example, the motor housing is capable of being adjusted with respect to the base 102, such that the router may achieve various cut depths when implemented with a router bit. Typically, bases include a furcation which may be drawn together by means of a clamping mechanism. In additional embodiments, a friction lock may be employed to secure the motor housing within the base. An adjustment mechanism 106 is further included in the router 100.
The adjustment mechanism includes a shaft 108, with a threaded portion, and a thread engaging member 110. The engaging member 110 contains a lug or ridge for alternately engaging and releasing at least a portion of the threads included on the shaft 108. The engaging member 110 may be biased, so the lug engages the shaft when unactuated. For instance, the engaging member 110 is biased by a spring so the motor housing is secured in a first orientation. When a user depresses the engaging member the lug and threads may disengage resulting in a second orientation being obtained. Additionally, fine depth adjustment may be achieved by rotating the shaft 108.
A hand grip attachment 112 is connected to the exterior of the base 102. The hand grip attachment 112 includes a lip 114 for at least partially supporting the router when grasped. The lip 114 extends generally outwardly from the exterior of the base. The portion of the lip 114 adjacent to the motor housing 104 of the present embodiment is either even with or less than the end of the base 102. For example, the lip may be even with the base adjacent to the motor housing 104. In a further embodiment, the top of the lip is below the end of the base. By orientating the top of the lip even with or below the end of the base a user is less likely to have their hand or fingers caught between the lip and the motor housing. For example, an unwary user's hand may be pinched between the motor housing and hand grip attachment during adjustment.
In further examples, the motor housing and/or the top of the lip generally opposing the housing may be angled away from the other so as to further minimize the pinch point. See generally FIG. 2, wherein the motor housing is angled generally away from the base/lip to minimize pinching.
In an additional aspect, a motor housing is contoured for grasping by a user. For instance, the motor housing is shaped so a user may pinch the motor housing between their fingers and thumb when adjusting depth. Supporting the motor housing in the previous manner may prevent the motor housing from dropping suddenly while changing depth. In additional embodiments, the motor housing includes a lip for at least partially supporting the motor housing when grasped. Moreover, the motor housing may include an elastomeric coating or formed at least partially of elastomeric material to promote user comfort and minimize muscle fatigue.
Referring to FIG. 3, a router adjustment device 300 is shown. The adjustment device 300 includes a base 302, a motor housing 304, and an adjustment mechanism 306. The adjustment mechanism includes a shaft 308, with a threaded portion, and a thread engaging member 310. The base 302, motor housing 304 and adjustment mechanism 306, including the shaft and engaging member 310 operate substantially as described with respect to FIGS. 1 and 2. The router adjustment device 300, of the present embodiment, includes a frictional zone 316 and a slidable zone 314. A frictional zone is included to at least partially resist the movement of the motor housing 304 with respect to the base. The frictional zone 316 is disposed either on the portion of the motor housing 304 received in the base or is disposed in an interior recess of the base 302. The slidable zone 314 comprises that portion of the outer wall of the motor housing 304 that does not include the frictional zone 316.
A frictional zone permits course adjustment, via disengaging the engaging member 310, and fine adjustment, via rotation of the shaft 308. The frictional zone at least partially inhibits rapid course adjustment which would damage the device 300 or potentially contact a user.
Frictional zones may be formed of brass, ceramic material, polymeric materials, elastomeric materials and the like for increasing the coefficient of friction between the friction zone and the generally opposing surface, such as the base. The increase in the coefficient of friction is greater than the coefficient of friction provided by a router or device not containing at least one frictional zone. For instance, the static coefficient of friction between the zone and opposing surface is between 0.15μ and 0.58μ, so as to permit adjustment while offering resistance, and thus increased safety.
In additional examples, as shown in FIG. 3A, a second frictional zone 320 and a second slidable zone 322 are employed to generally oppose the first frictional zone 316 and first slidable zone 304. In examples where two frictional zones are employed, the first and second frictional zones are disposed generally opposite with one frictional zone 320 disposed on the base and the other frictional zone 316 disposed on the motor housing.
Referring to FIGS. 4A, 4B and 4C an apparatus 400 for controlling router adjustment is discussed. The apparatus 400 includes a base 402, a motor housing 404 and adjustment mechanism 406, which operate substantially a previously described.
Referring to FIG. 4A, in a first example, a compression spring 418 is disposed in the base 402 so the shaft 408 is generally biased. For instance, when the shaft 408 included in the adjustment mechanism 406 is disengaged from the engaging member 410 the spring at least partially supports the shaft, and thus the motor housing, such as by contacting a shoulder included on the shaft 408. By implementing the present apparatus when the engagement member 410 is disengaged from the shaft the spring acts to prevent rapid adjustment which may damage the apparatus or injure the user. The present apparatus retains the ability to permit a wrench to interact with a mechanical connection included on the shaft to permit base end adjustment. In additional examples, a washer may be disposed on the end of the spring 408 contacting the shaft for providing a suitable interface for the spring/shaft.
Referring to FIG. 4B, in a second example, a biased lever is disposed in the base 402 adjacent to the threaded portion of the shaft 408. In the present example a coiled spring with a lever arm 420 is utilized. The lever 420 acts to at least partially restrain the longitudinal movement of the threaded shaft by alternately engaging and releasing the threads. For example, when the thread engaging member is disengaged from the shaft 408, the lever 420 may permit gradual change.
Referring to FIG. 4C, in a further example, a gasket 422 formed of elastomeric or polymeric material is disposed in the base adjoining the shaft 408, included in the apparatus 400. For instance, the gasket 422 is formed of a semi-rigid plastic which couples to the shaft to at least partially restrain the shaft during longitudinal travel, such as when the shaft 408 is disengaged from the thread engaging member. Additionally, an inner ring formed of a metal such as brass, a ceramic and the like may be utilized to increase the durability of the gasket 422. For instance, a gasket may include a washer with a metallic inner ring surrounded by an elastomeric material such that the inner ring contacts the shaft 408.
Referring to FIG. 4D, in an additional example, a frictional zone 424 is attached to the thread engaging member 410. The frictional zone 424 is disposed in the aperture generally opposite the lug or ridge for engaging the threads included on the shaft 408. The frictional zone may contact the shaft 408, thus retarding the longitudinal motion of the shaft, such as when the shaft is disengaged from the threaded engaging member 410. For instance, when a user inadvertently releases the thread engaging member 410 the frictional zone may come in contact with the shaft, and resulting in a slower travel.
Referring now to FIG. 5A, a router adjustment device 500 is shown. The router device 500 includes a base 502, a motor housing 504 and an adjustment mechanism 506, including a shaft 508 and thread engaging member 510. All of the above are substantially similar as discussed previously. The device 500, of the present embodiment, further includes a brake element disposed in the base generally perpendicular to the axis motion for the motor housing 504.
For example, the brake element is a biased pin 526 which is suitable for contacting the motor housing. Preferably, the pin 526 is biased in a disengaged orientation. For example, a user may wish to depress the pin 526, and thus contact the motor housing and at least partially resist or inhibit motor housing motion, such as when performing a course adjustment. The pin 526 may be located so as to permit the user to utilize one hand to manipulate the pin 526 and the thread engaging member 510.
In a further embodiment, the portion of the pin 526 contacting the motor housing may be formed of brass, ceramic material, plastic and the like for at least partially retarding the longitudinal motion of the motor housing without marring the motor housing 504.
Referring to FIG. 5B, in an additional example, the biased pin includes an angled end directed towards a generally opposing angled surface included on the thread engagement member 510. Employing the present arrangement, the pin 526 automatically engages when the engaging member 510 is actuated, thus resulting in the pin 526 being forced towards the motor housing 504.
Referring now to FIG. 5C, in a further example, a contact zone 528 mounted to the thread engaging member 510. For instance, the thread engaging member 510 includes an angled or curved protrusion, directed towards the motor housing, with a contact zone 528 for contacting the motor housing 504 when the engaging member 510 is pressed. The contact zone may be formed of brass, ceramic material, plastic and the like for at least partially resisting the longitudinal motion of the motor housing without marring the motor housing 504.
It is believed that present invention and many of its attendant advantages will be understood by the forgoing description. It is also believed that it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely an explanatory embodiment thereof. It is the intention of the following claims to encompass and include such changes.

## Claims

1. A router adjustment device comprising:
a base for supporting a router;
a motor housing adjustably secured by the base for movement along an axis to a position relative to the base;
a frictional zone and a slidable zone substantially longitudinally disposed on one of the motor housing and the base; and
an adjustment mechanism for adjusting the position of the housing relative to the base, the adjustment mechanism including:
a shaft connected to the motor housing for rotation about an axis, having a threaded portion, and
a thread engaging member connected to the base, capable of selectively engaging with the threaded portion;

wherein the frictional zone has a greater coefficient of friction than the slidable zone to at least partially resist the movement of the motor housing with respect to the base, and wherein the frictional zone and the slidable zone are separate and apart from the adjustment mechanism, the shaft, and the thread engaging member.

2. The router of claim 1, wherein the frictional zone comprises brass.

3. The router of claim 1, wherein the frictional zone comprises at least one of a ceramic, a polymer, and an elastomeric material.

4. The router of claim 1, wherein the static coefficient of friction between the frictional zone and at least one of the base and the motor housing is in the range of between approximately 0.15μ and 0.58μ.

5. The router of claim 1, wherein the motor housing is at least partially formed from an elastomeric material.

6. The router of claim 1, wherein the motor housing includes a grasping zone for aiding grasping by a user.

7. The router of claim 1, wherein the motor housing is contoured to fit at least a portion of a user's hand.

8. A router adjustment device comprising:
a base for supporting a router;
a motor housing adjustable secured by the base for movement along an axis to a position relative to the base;
a first frictional zone disposed substantially longitudinally on the motor housing;
a first slidable zone disposed adjacent to the first frictional zone on the motor housing;
a second frictional zone disposed substantially longitudinally on the base generally opposing the first frictional zone;
a second slidable zone disposed adjacent to the second frictional zone on the base generally opposing the first slidable zone; and
an adjustment mechanism for adjusting the position of the housing relative to the base, the adjustment mechanism including
a shaft connected to the motor housing for rotation about an axis, having a threaded portion, and
a thread engaging member connected to the base, capable of selectively engaging with the threaded portion;

wherein the first and second frictional zones have a greater coefficient of friction than the first and second slidable zones to at least partially resist the movement of the motor housing with respect to the base, and wherein the first and second frictional zones and the first and second slidable zones are separate and apart from the adjustment mechanism, the shaft, and the thread engaging member.

9. The router adjustment device of claim 8, wherein at least one of the first frictional zone and the second frictional zone comprises brass.

10. The router adjustment device of claim 8, wherein at least one of the first frictional zone and the second frictional zone comprises at least one of a ceramic, a polymer, and an elastomeric material.

11. The router adjustment device of claim 8, wherein the static coefficient of friction between the first frictional zone and second frictional zone is in the range of between approximately 0.15μ and 0.58μ.

12. The router adjustment device of claim 8, wherein the motor housing is at least partially formed of an elastomeric material.

13. The router adjustment device of claim 8, wherein the motor housing includes a grasping zone for aiding grasping by a user.

14. The router adjustment device of claim 8, wherein the motor housing is contoured to fit at least a portion of a user's hand.

15. A router adjustment device comprising:
a base for supporting a router, the base defining a generally cylindrical interior recess;
a motor housing adjustably secured by the base for movement along an axis to a position relative to the base;
a frictional zone and a slidable zone disposed substantially longitudinally on at least one of the exterior of the motor housing and the generally cylindrical interior recess of the base, the frictional zone having a coefficient of friction which is greater than the coefficient of the slidable zone; and
an adjustment mechanism for adjusting the position of the housing relative to the base, the adjustment mechanism including:
a shaft connected to the motor housing for rotation about an axis, having a threaded portion, and
a thread engaging member connected to the base, capable of selectively engaging with the threaded portion;

wherein the frictional zone at least partially resists the movement of the motor housing with respect to the base, and wherein the frictional zone and the slidable zone are separate and apart from the adjustment mechanism, the shaft, and the thread engaging member.

16. The router adjustment device of claim 15, wherein the frictional zone comprises brass.

17. The router adjustment device of claim 15, wherein the frictional zone comprises at least one of a ceramic, a polymer, and an elastomeric material.

18. The router adjustment device of claim 15, wherein the static coefficient of friction between the frictional zone and at least one of the base and the motor housing is in the range of between approximately 0.15μ and 0.58μ.

19. The router adjustment device of claim 15, wherein the motor housing includes a grasping zone for aiding grasping by a user.

20. The router of claim 1, wherein the frictional zone is disposed in a substantially longitudinal strip on one of the motor housing and the base.

21. The router of claim 1, wherein the frictional zone and the slidable zone are disposed on an exterior surface of the motor housing.

22. The router of claim 1, wherein the frictional zone and the slidable zone are disposed on an interior surface of the base.

23. The router adjustment device of claim 8, wherein the first frictional zone is disposed in a substantially longitudinal strip.

24. The router adjustment device of claim 23, wherein the second frictional zone is disposed in a substantially longitudinal strip on one of the motor housing and the base.

25. The router adjustment device of claim 15, wherein the frictional zone is disposed in a substantially longitudinal strip on one of the motor housing and the base.

26. The router adjustment device of claim 15, wherein the frictional zone and the slidable zone are disposed on an exterior surface of the motor housing.

27. The router adjustment device of claim 15, wherein the frictional zone and the slidable zone are disposed on an interior surface of the base.

28. A router comprising:
a base for supporting the router, the base having a sleeve with an inner surface;
a motor housing configured to be received in the base for axial movement relative to the base, the motor housing having an outer surface configured to abut against the inner surface of the sleeve;
an adjustment mechanism configured to adjust an axial position of the motor housing relative to the base, the adjustment mechanism including a shaft with a threaded portion coupled to one of the motor housing and the base for rotation about an axis of the shaft, and a thread engaging member coupled to the other of the motor housing and the base for selectively engaging the threaded portion,
wherein at least one of the inner surface of the base sleeve and the outer surface of the motor housing includes a slidable zone and a frictional zone adjacent to the slidable zone and having a greater coefficient of friction than the slidable zone, the frictional zone at least partially resisting movement of the motor housing relative to the base, and wherein the frictional zone and the slidable zone are separate and apart from the adjustment mechanism, the shaft, and the thread engaging member.

29. The router of claim 28, wherein the frictional zone at least partially resists movement of the motor housing relative to the base when the thread engaging member is disengaged from the threaded portion of the shaft.

30. The router of claim 28, wherein the frictional zone is disposed on at least one substantially longitudinal strip.

31. A router comprising:
a base for supporting the router, the base having a sleeve with an inner surface;
a motor housing configured to be received in the base for axial movement relative to the base, the motor housing having an outer surface configured to abut against the inner surface of the sleeve;
an adjustment mechanism configured to adjust an axial position of the motor housing relative to the base, the adjustment mechanism including a shaft with a threaded portion coupled to one of the motor housing and the base for rotation about an axis of the shaft, and a thread engaging member coupled to the other of the motor housing and the base for selectively engaging the threaded portion,
wherein the inner surface of the base sleeve includes a first slidable zone and a first frictional zone, the outer surface of the motor housing includes a second slidable zone and a second frictional zone, the first and second frictional zones abuting each other and having a greater coefficient of friction than the first and second slidable zones to at least partially resist movement of the motor housing relative to the base, and wherein the first and second frictional zones and the first and second slidable zones are separate and apart from the adjustment mechanism, the shaft, and the thread engaging member.

32. The router of claim 31, wherein the frictional zone at least partially resists movement of the motor housing relative to the base when the thread engaging member is disengaged from the threaded portion of the shaft.

33. The router of claim 31, wherein the frictional zone is disposed on at least one substantially longitudinal strip.

34. A router comprising:
a motor housing that includes a substantially cylindrical outer wall defining a longitudinal axis;
a threaded shaft coupled to a side of the motor housing outside of the outer wall and extending along and rotatable about a shaft axis that is substantially parallel to the longitudinal axis;
a base having a substantially cylindrical sleeve that slidably receives the outer wall of the motor housing for movement along the longitudinal axis;
a flange mounted to a side of the sleeve and outside of the sleeve, the flange defining an aperture for receiving the threaded shaft;
a thread engaging member coupled to the flange and extending into the aperture, the thread engaging member being moveable between a first position where the thread engaging member is engaged with the threaded shaft so that rotation of the shaft causes movement of the motor housing relative to the base in the longitudinal direction, and a second position where the thread engaging member is disengaged from the threaded shaft; and
a longitudinal friction strip attached to the cylindrical outer wall of the motor housing, the friction strip having a greater coefficient of friction than the outer wall so that the friction strip inhibits movement of the motor housing relative to the base.