| WO/1993/008005 | DEPTH OF CUT LOCK MECHANISM FOR A PLUNGE TYPE ROUTER |
| JP2023134827 | ROUTER |
| JP2005125795 | ROUTER |
MCCRACKEN ROBERT E (US)
WATSON JAMES B (US)
| US2842173A | 1958-07-08 | |||
| US1899883A | 1933-02-28 | |||
| US3363510A | 1968-01-16 | |||
| US4108225A | 1978-08-22 |
| 1. | A router comprising: a motor housing having an external cylindrical portion, said cylindrical portion having a first longi tudinal region with a substantially smooth surface and a second longitudinal region having an external screw thread; a base having a cylindrical bore for slidably receiving therein said first longitudinal region of said motor housing cylindrical portion; an adjustment ring including means for engag¬ ing said screw thread on said motor housing and means for rotationally engaging said base; and means for preventing relative rotation between said motor housing and said base. |
| 2. | The router according to claim 1 further comprising: means for releasably securing said adjustment ring to said motor housing and said base so as to maintain the relative positions of said base and said motor housing. |
| 3. | The router according to claim 1 wherein said relative rotation preventing means includes a longitudinal groove in the surface of one of said motor housing and said base and a complemental projection on the other of said motor housing and said base. |
| 4. | The router according to claim 1 further comprising: means for adjustably setting limits on the range of angular rotation of said adjustment ring relative said base. |
| 5. | The router according to claim 1 wherein said adjustment ring comprises two hingedly joined substantially semicylindrical portions and each of said adjustment ring portions has a complemental screw thread segment for engaging said motor housing external screw thread. |
| 6. | The router according to claim 5 wherein said base is formed with an annular groove and each of said adjustment ring portions has a projection for engaging said base annular groove. |
| 7. | The router according to claim 1 wherein said adjustment ring is split forming an opening between two opposed ends, said router further comprising: clamp means for releasably securing said adjustment ring to said motor housing so as to maintain the position of said base relative said motor housing, including: a first projection formed on said adjust¬ ment ring adjacent a first one of said opposed ends; a second projection formed on said adjustment ring adjacent the second one of said opposed ends; said first and second projections each being formed as respective mirrorimage halves of a frustoconical structure; an adjustment ring clamp knob having an inner surface adapted to slidably engage the frustoconical surfaces of said first and second projections; and means for supporting said knob with said inner surface engaging the frustoconical surfaces of both said first and second projections so that movement of said k'nob toward said adjustment ring draws said first and second projections toward each other and movement of said knob away from said adjustment ring allows said first and second projections to separate; whereby movement of said adjustment ring clamp knob may be effected by an operator for selectively securing and releasing said adjustment ring with respect to said motor housing. |
| 8. | The router according to claim 7 wherein said clamp knob has a central internally threaded boss and said supporting means includes a threaded member fixed against rotation with respect to said adjustment ring and threadedly engaged with said clamp knob boss. |
| 9. | The router according to claim 8 wherein said surfaces of said first and second projections are shaped such that at a section taken along a plane orthogonal to said threaded member each of said surfaces describes an arc of a circle having a predetermined diameter irrespective of the position of said plane along said surfaces, the center of said circle varying linearly as said plane moves along said threaded member. |
| 10. | The router according to claim 9 wherein said clamp knob inner surface is frustoconical to provide substantial surface engagement with said first and second projection surfaces. |
| 11. | The router according to claim 1 further comprising means for adjustably setting limits on the range of angular rotation of said adjustment ring, including: a first beveled annular surface on said adjustment means at one longitudinal end thereof; a second beveled annular surface on one of said motor housing and said base adjacent said first beveled annular surface, said first and second beveled annular surfaces together forming a Vshaped annular groove; a tab on said adjustment means extending toward and terminating before said first beveled annular surface; a first generally circular stop ring rotatable along said annular groove, said first stop ring includ¬ ing a first interfering projection extending into the path of travel of said adjustment means tab; a second generally circular stop ring rotat¬ able along said annular groove adjacent said first stop ring, said second stop ring including a second interfer¬ ing projection extending into the path of travel of said adjustment means tab; and means for setting the angular positions of said first and second stop rings along said annular groove with said first and second projections flanking said adjustment means tab so that said projections define limits on the extent of angular rotation of said adjustment means. |
| 12. | The router according to claim 11 wherein said stop rings setting means includes: first securing means for securing said first stop ring to said second beveled annular surface; and second securing means for securing said second stop ring to said first stop ring. |
| 13. | The router according to claim 12 wherein said first stop ring includes means for adjusting the circumference of said first stop ring and said first securing means includes complementary mating surface regions formed on said first stop ring and said second. beveled annular surface so that when the circumference of said first stop ring is adjusted below a predeter¬ mined circumference said surface regions engage with each other and said first stop ring is prevented from rotating along said annular groove. |
| 14. | The router according to claim 13 wherein said complementary mating surface regions comprise at least one projecting rib on said second beveled annular surface directed transversely to the direction of rotation of said first stop ring and a plurality of interfering grooves formed on said stop ring, said interfering grooves being sized and oriented so that one of said interfering grooves engages said at least one projecting rib when the circumference of said first stop ring is less than said predetermined circumference. |
| 15. | The router according to claim 14 wherein said first and second stop rings include surfaces which abut each other and said second securing means includes complementary mating serrated formations on said abut ting surfaces. |
| 16. | The router according to claim 13 wherein said first stop ring is resilient and is formed with an opening between two opposed ends, said circumference adjusting means joining said two ends with a selective spacing therebetween. |
| 17. | The router according to claim 16 wherein said circumference adjusting means includes: an adjustment projection on one of said ends, said adjustment projection being formed with a circum ferentially directed opening; and a tab on the other of said ends, said tab being circumferentially directed toward said adjustment projection and adapted to extend through said projection opening, said tab being formed with two interfering barbs sized and spaced so that when said tab extends through said adjustment projection opening with a first of said barbs engaging said adjustment projection the circumference of said first stop ring is sufficiently large that said first stop ring is free to rotate along said groove and when said tab extends through said adjustment projection opening with a second of said barbs engaging said adjustment projection the circumfer¬ ence of said first stop ring is below said predetermined circumference so that said first stop ring is prevented from rotating along said annular groove. |
| 18. | The router according to claim 18 wherein said first interfering projection of said first stop ring is located on said other end and said tab is secured to said first interfering projection. |
| 19. | The router according to claim 18 wherein said complementary mating surface regions comprise at least one projecting rib on said second beveled annular surface directed transversely to the direction of interfering grooves formed on said first stop ring, said interfering grooves being sized and oriented so that one of said interfering grooves engages said at least one projecting rib when the circumference of said first stop ring is less than said predetermined circumference. AMENDED CLAIMS [received by the International Bureau on 29 April 1992 (29.04.92); original claims 1,2,1419 amended; remaining claims unchanged (3 pages)3 1 A router comprising: a motor housing having an external cylindrical portion, said cylindrical portion having a first longitudinal region and a second longitudinal region having an external screw thread; a base having a cylindrical bore for slidably receiving therein said first longitudinal region of said motor housing cylindrical portion; an adjustment ring substantially encircling said motor housing and said base, said adjustment ring having a screw thread segment for engaging said screw thread on said motor housing and means for rotationally engaging said base; means for preventing relative rotation between said motor housing and said base; and clamp means for releasably circumferentially clamping said adjustment ring about said motor housing and said base, so as to maintain the relative position of said motor housing and said base once a desired depth of cut has be selected. |
| 20. | 2 The router according to claim 1 wherein said means for rotationally engaging said base includes an annular groove located in one of said adjustment ring and said base and a complemental projection on the other of said adjustment ring and said base. |
| 21. | 3 The router according to claim 1 wherein said relative rotation preventing means includes a longitudinal groove in the surface of one of said motor housing and said base and a complemental projection on the other of said motor housing and said base. |
| 22. | 4 The router according to claim 1 further comprising: means for adjustably setting limits on the range of angular rotation of said adjustment ring relative said base. beveled annular surface so that when the circumference of said first stop ring is adjusted below a predetermined circumference said surface regions engage with each other and said first stop ring is prevented from rotating along said annular groove. |
| 23. | 14 The router according to claim 13 wherein said complemen¬ tary mating surface regions comprise at least one projecting rib on said second beveled annular surface directed transversely to the direction of interfering grooves formed on said first stop ring, said interfering grooves being sized and oriented so that one of said interfering grooves engages said at least one projecting rib when the circumference of said first stop ring is less than said predetermined circumference. |
| 24. | 15 The router according to claim 13 wherein said first stop ring is resilient and is formed with an opening between two opposed ends, said circumference adjusting means joining said two ends with a selective spacing therebetween. |
| 25. | 16 The router according to claim 15 wherein said circumfer¬ ence adjusting means includes: an adjustment projection on one of said ends, said adjustment projection being formed with a circumferentially directed opening; and an interfering projection on the other of said ends, said interfering projection having a tab formed thereon, said tab being circumferentially directed toward said adjustment projection and adapted to extend through said projection opening, said tab being formed with two barbs sized and spaced so that when said tab extends through said adjustment projection opening with a first of said barbs engaging said adjustment projection the circumference of said first stop ring is sufficiently large that said first stop ring is free to rotate along said groove and when said tab extends through said adjustment projection opening with a second of said barbs engaging said adjustment projection the circumference of said first stop ring is below said predetermined circumference so that said first stop ring is prevented from rotating along said annular groove. |
| 26. | 17 The router according to claim 16 wherein said first barb of said tab is located distal to said interfering projection relative said second baib. |
| 27. | 18 The router according to claim 13 wherein said complemen¬ tary mating surface regions comprise at least one projecting rib on said second beveled annular surface directed transversely to the direction of rotation of said first stop ring and a plurality of interfering grooves formed on said stop ring, said interfering grooves being sized and oriented so that one of said interfering grooves engages said at least one projecting rib when the circumference of said first stop ring is less than said predetermined circumference. |
| 28. | 19 The router according to claim 15 wherein said first and second stop rings include surfaces which abut each other and said second securing means includes complementary mating serrated formations on said abutting surfaces. STATEMENΓ UNDER ARTICLE 19 This response to the International Search Report of the United States International Searching Authority for the present international application under the Patent Coopera¬ tion Treaty has amended claims 1, 2, 16 and 17 in an effort to more specifically describe the applicant's invention. In claim 1, the adjustment ring has been amended in the third subparagraph of the amended claim on page 14, lines 810, to indicate that the adjustment ring "substantially surround said motor housing and said base, said adjustment ring having a screw thread segment for engaging said housing external screw thread." The last subparagraph of claim 1 on page 14, lines 1214, has been added to include a "clamp means" which "releasably circumferentially clamps" the adjustment ring to maintain the relative position of said motor housing and said base "once a desired depth of cut has been selected." The reference to "a substantially smooth surface" of the first longitudinal region originally in claim 1, page 14, lines 45 has been deleted as it is an unneces¬ sary limitation. Claim 2 on page 14, lines 1621 has been amended to indicate that the "means for rotationally engaging said base includes an annular groove located in one of said adjustment ring and said base and a complemental projection on the other of said adjustment ring and said base." Claim 16 has been amended in the second subpara¬ graph on page 18, lines 20 and 21 to delete "a tab" and add "an interfering projection" on the other of said ends, "said interfering projection having a tab formed thereon". Line 22 has been amended to delete "interfering" immediately preced¬ ing "barbs" to correct an inadvertent typographical error. Claim 17 on page 19, lines 35 has been amended to indicated that "said first barb of said tab is located distal to said interfering projection relative said second barb." Former claim 19 on page 19, lines 1826 has been renumbered as claim 14 now depending from claim 13. This amendment has been made to properly reflect the dependance of claim 14 on claim 13. Former claim 16 on page 18, lines 21 25 has been renumbered as claim 15. Former claims 17 and 18 on page 18, lines 2632 and page 19, lines 117 depending from former claim 16 have been renumbered as claims 16 and 17 to properly reflect their dependance on newly numbered claim 15. All former claims 1418 have accordingly been renum¬ bered. By renumbering of the claims, the related dependent numbers have been affected and have also been renumbered accordingly. It is believed that the claims, as amended, distinguish the Turner et al. reference and Turner et al. combined with the secondary references as cited by the Examiner. It is thus respectfully submitted that the present PCT application now defines a novel invention as well as having industrial applicability so as to thereby be patent able. An indication to that effect upon the Preliminary. |
Technical Field
This invention relates to portable electric router tools and, more particularly, to an arrangement for providing an adjustable depth of cut adjustment mechanism.
Background Art
Prior art routers have been constructed with various kinds of depth of cut adjustment mechanisms. One such type of mechanism utilizes a rack and pinion arrangement whereas another type utilizes an externally threaded motor housing. All of the known mechanisms suffer from various drawbacks, including relatively large numbers of parts, difficulty of assembly, and inconvenience in use.
Prior router depth of cut adjustment mecha¬ nisms utilizing a split adjustment ring have included projections on opposite sides of the split which are squeezed together to effect a clamping action by means of a threaded member arranged generally tangential to the ring. These arrangements are not entirely satisfac¬ tory because, for example, there is insufficient room for manipulating the threaded member.
When using a router, the operator often desires to quickly change the depth of cut from one preset depth to another present depth. In the particu¬ lar router depth of cut adjustment mechanism considered herein, the router includes a motor housing with an
external cylindrical portion and a base with a cylindri¬ cal bore for slidably receiving therein the cylindrical portion of the motor housing. A depth of cut adjustment ring engages the motor housing and the base and is rotatable to effect relative longitudinal displacement of the motor housing with respect to the base, the router further including an arrangement for preventing relative rotation between the motor housing and the base.
It is therefore an object of this invention to provide an improved depth of cut adjustment mechanism for a router which does not suffer from the drawbacks enumerated above.
It is therefore another object of this inven- tion to provide a more effective split ring clamping arrangement.
It is an object of the present invention to provide an arrangement for adjustably setting limits on the range of angular rotation of the rotatable depth of cut adjustment ring.
Disclosure Of The Invention
The foregoing, and additional objects are attained in accordance with the principles of this invention by providing a depth of cut adjustment mecha- nism for a router wherein the router motor housing has an external cylindrical portion with a first longitudi¬ nal region having a substantially smooth surface and a second longitudinal region having an external screw thread. A cutting tool is mounted to the shaft of the motor contained within the motor housing and extends beyond one end of the motor housing. The router also
includes a base having a cylindrical bore for slidably receiving therein the smooth surface longitudinal region of the motor housing. The depth of cut adjustment mechanism includes an adjustment ring which engages the screw thread on the motor housing and rotationally engages the base, and further includes an arrangement for preventing relative rotation between the motor housing and the base. By means of this arrangement, rotation of the adjustment ring effects relative longi- tudinal motion between the motor housing and the base, so that the distance which the cutting tool projects beyond the base may be varied to thereby adjust the cutting depth.
In accordance with an aspect of this inven- tion, there is further provided an arrangement for releasably securing the adjustment ring to the motor housing and the base so as to maintain the relative positions of the base and the motor housing.
In accordance with another aspect of this invention, the arrangement for preventing relative rotation includes a keyway and slot combination formed in the motor housing and the base.
In accordance with a further aspect of this invention, there is also provided an arrangement for adjustably setting limits on the range of angular rotation of the adjustment ring relative the base, thereby enabling the tool operator to make quick changes between two different depths of cut.
In accordance with a further aspect of this invention, there is also provided a pair of stop rings, each having an interference projection, and each being independently rotatably mounted on the router base.
These rings may be set with their interference projec¬ tions at any desired angular orientation on the base. The depth of cut adjusting ring has a tab fixedly mounted thereon which extends to a point between the interfering projections so as to limit the angular rotation of the adjustment ring.
In accordance with a further aspect of this invention, there is also provided a clamping arrangement for use in the environment described above which in- eludes first and second projections formed on the split ring adjacent opposite sides of the split. Each of the projections has a frusto-conical camming surface. A circular knob mounted for threaded rotation on a bolt passing through the projections radially with respect to the router motor housing bears against the camming surfaces so as to squeeze the ring to effect a clamping action as the knob is moved inwardly.
In accordance with an aspect of this inven¬ tion, the surfaces of the first and second projections are shaped such that at a section taken along a plane orthogonal to the bolt each of the surfaces describes an arc of a circle having a predetermined diameter irre¬ spective of the position of the plane along the surfac¬ es, the center of the circle varying linearly as the plane moves along the bolt.
In accordance with another aspect of this invention, the clamp knob inner surface is frusto- conical to provide substantial surface engagement with the first and second projection surfaces.
BriefDescription OfTheDrawings
The foregoing will be more readily apparent upon reading the following description in conjunction with the drawings in which like elements in different figures thereof have the same reference numeral applied thereto and wherein:
FIGURE 1 is an elevational view, partially cut away, showing a router constructed in accordance with this invention;
FIGURE 2 is a perspective view of the motor housing of the router shown in Figure 1;
FIGURE 3 is a perspective view of the top central portion of the base of the router shown in Figure 1;
FIGURE 4 is a top plan view of the adjustment ring of the router shown in Figure 1, shown in its * fully open state;
FIGURE 5 is an elevational view of the opened adjustment ring shown in Figure 4;
FIGURE 6 is a cross-section of the adjustment ring taken along the line 6-6 in Figure 5;
FIGURE 7 is a cross-sectional view showing details of the clamping knob on the adjustment ring;
FIGURE 7A is a detail of the surface of the adjustment ring clamp projection;
FIGURE 8 is a top plan view of a stop ring of the router shown in Figure 1, shown in its fully open state;
FIGURE 9 is an elevational view of the opened stop ring shown in Figure 8;
FIGURE 10 is an enlarged detail of the stop ring shown in Figure 9; and
FIGURE 11 is an elevational view, partly in cross-section, showing how the motor housing, the base, the adjustment ring and the stop rings of the router shown in Figure 1 fit together.
Best Mode For Carrying Out The Invention
Referring now to the drawings. Figure 1 illustrates a router, designated generally by the reference numeral 100, which is constructed in accor¬ dance with the principles of this invention. The router includes a motor housing 102 which contains a motor (not shown) powered through a switch 105 and a line cord 104 and having a rotating output shaft on which is mounted a collet 106 for holding a cutting tool (not shown) . The motor, its mounting within the motor housing 102, and the cutting tool collet form no part of the present invention and will not be described in any further detail.
The motor housing 102 is supported in a base 108, in a manner to be described in full detail herein¬ after, which includes a pair of handles 110 by means of which an operator can manipulate the router 100 along a work surface. The motor housing 102 is supported in the base 108 so that the cutting tool can extend outwardly beyond the lower support surface 112 of the base 108. In operation of the router 100, the lower support surface 112 rests on the upper surface of the work and the distance that the cutting tool extends beyond the
lower support surface 112 determines the depth of cut of the router 100. This depth of cut may be adjusted by varying the relative longitudinal position of the motor housing 102 relative the base 108.
As is best shown in Figure 2, the motor housing 102 is generally cylindrical in external config¬ uration. A first longitudinal region 114 of the motor housing 102 has a generally smooth surface, while a second longitudinal region 116 is formed with an exter- nal screw thread 118.
As shown in Figure 3, the base 108 has a cylindrical bore 120 which is sized to slidably receive therein the smooth longitudinal region 114 of the motor housing 102. In order to prevent relative rotation between the motor housing 102 and the base 108, the cylindrical bore 120 of the base 108 is formed with a longitudinal groove 122 and the motor housing 102 is formed with a projection 124 complemental thereto.
The present invention is concerned with the arrangement for adjusting the depth of cut of the router 100. Accordingly, there is provided an adjustment ring 126 which engages both the screw thread 118 on the motor housing 102 and also rotationally engages the base 108. Since the motor housing 102 cannot partake of rotational motion relative the base 108 because of the groove 122 and the projection 124, rotation of the adjustment ring 126 effects longitudinal displacement of the motor housing 102 relative the base 108, which varies the distance that the cutting tool projects beyond the lower support surface 112. Subsequent clamping of the adjust¬ ment ring 126 to the motor housing 102 and the base 108 maintains the desired depth of cut adjustment.
Thus, the adjustment ring 126 is formed with an internal screw thread 128 (Figure 5) which is comple- mental to the external screw thread 118 of the motor housing 102. The base 108 is formed with an annular groove 130 at its upper end and the adjustment ring is formed with an inwardly directed projection, or flange, 132 which engages the annular groove 130. Accordingly, rotation of the adjustment ring 126 does not affect its longitudinal position with respect to the base 108 but due to the pitch of the screw threads 118,128, the motor housing 102 is longitudinally displaced.
Preferably, the adjustment ring 126 is a split ring hinged at 134, as best shown in Figures 4 and 5. Each half of the adjustment ring 126 is generally se i- circular in plan. This allows for economical molding of the adjustment ring 126 and easy assembly onto the router 100. The adjustment ring 126 is preferably molded of a plastic material so that it is inherently resilient.
After the adjustment ring 126 is rotated to achieve a desired depth cut, the ring 126 must be clamped to the motor housing 102 and the base 108 to maintain that depth of cut setting. Toward that end, the adjustment ring 126 is formed with a first projec- tion 136 adjacent a first of the opposed ends flanking the split of the ring 126 and a second projection 138 adjacent the other opposed end flanking the split of the ring 126. Preferably, the projections 136,138 are mirror image halves of a frusto-conical structure. When pressed together, the projections 136,138 provide a recess 140 which holds the head 142 of a threaded member 144 against rotation. A circular clamp knob 146 is provided. The knob 146 has an internally threaded boss 148 which is threadedly engaged with the threaded member
144, as is best shown in Figure 7. The clamp knob 146 has an inner camming surface 150 which bears against the frusto-conical surfaces 152,154 of the projections 136,138, respectively. Thus, clockwise rotation of the clamp knob 146 closer to the motor housing 102 to draw the projections 136,138 toward each other, thereby closing the gap between the opposed ends of the adjust¬ ment ring 126 and clamping the adjustment ring 126 to the motor housing 102 and the base 108. Conversely, counterclockwise rotation of the clamp knob 146 loosens the adjustment ring 126. Since the clamp knob 146 extends away from the router 100 to a region which is free of all obstructions, it is very easily manipulated by the operator.
The clamp knob 146 is circular, with the inner camming surface 150 being beveled so that it is frusto- conical. To provide substantial engagement of the inner camming surface 150 with the surfaces 152,154 of the projections 136,138 of the adjustment ring 126, the surfaces 152,154 are shaped such that at a section taken along a plane orthogonal to the threaded member 144, each of the surfaces 152,154 describes an arc of a circle having a predetermined fixed diameter irrespec¬ tive of the position of the plane along the surfaces 152,154. The center of that circle varies linearly as the plane moves along the threaded member 144. Thus, as the clamp knob 146 is tightened on the threaded member 144 and the projections 136,138 are moved closed togeth¬ er, the inner camming surface 150 always engages the same size frusto-conical surface.
Advantageously, the router 100 is arranged with adjustable limit stops for the depth of cut adjust¬ ment mechanism so that the operator can quickly change the depth of cut setting between first and second preset
depths of cut. These limit stops are provided on stop rings which encircle the base 108 and which may be fixed to the base 108 in preset angular orientations. The limit stops cooperate with structure on the adjustment ring 126 to provide limits to the range of angular rotation of the adjustment ring 126.
Figures 8-10 illustrate a stop ring 156 which may be utilized for the above-described function. A pair of such stop rings 156 are utilized, the stop rings being rotated 180 * from each other when in use, as will be described in full detail hereinafter. Like the adjustment ring 126, the stop ring 156 is a split ring hinged at 158. Each half of the stop ring 156 is generally semi-circular in plan (Figure 8) while being generally triangular in cross-section as can best be seen in Figure 11. Thus, the inner surface of the stop ring 156 is at an angle of approximately 45 * . This inner surface is serrated to form a plurality of grooves 160. The wider end surface 162 of the stop ring 156 is also serrated.
The stop ring 156 is preferably molded of a plastic material so that it is inherently resilient. The stop ring 156 is formed with an interfering projec¬ tion 164 at one end and an adjustment projection 166 at its other end. The projections 164,166 are thus opposed across the opening of the split stop ring 156, and the spacing therebetween determines the overall circumfer¬ ence of the stop ring 156. To adjust that circumfer¬ ence, the adjustment projection 166 is formed with an opening 168 which is directed circumferentially of the stop ring 156. On the interfering projection 164, there is formed a tab 170 circumferentially directed toward the adjustment projection 166. The tab 170 includes a first barb 172 and a second barb 174 and is adapted for.
insertion through the opening 168. When the first barb 172 engages the projection 166, the circumference of the stop ring 156 is relatively large and when the second barb 174 engages the projection 166, the circumference of the stop ring 156 is smaller.
To accommodate the stop rings 156, the lower end of the adjustment ring 126 is formed with a beveled annular surface 176, as best shown in Figure 11. The base 108 is formed with a beveled annular surface 178 adjacent the annular groove 130, so that when the adjustment ring 126 is installed on the base 108 the surfaces 176 and 178 together form a V-shaped annular groove. The pair of stop rings 156 fit within this groove, with one of the stop rings oriented 180° with respect to the other stop ring, as is best shown in Figure 11.
The effectively fix the position of the stop rings 156 in the V-shaped annular groove, the beveled annular surface 178 is formed with a number of ribs 180 which are directed transversely to the direction of rotation of the stop rings 156 in the V-shaped annular groove. The ribs 180 cooperate with the serration grooves 160 of the lower one of the stop rings 156 when the second barb 174 engages the adjustment projection 166 so that the stop ring 156 is at its smaller circum¬ ference. In this state, the lower stop ring 156 is effectively clamped and prevented from rotating. The cooperation of the serrations on the end surfaces 162 of the stop rings 156 prevents the upper one of the stop rings 156 from rotating with respect to the lower one of the stop rings 156 when the second barb 174 of the upper stop ring 156 engages the adjustment projection 166 of the upper stop ring 156.
For cooperation with the interfering projec¬ tions 164 of the stop rings 156 so as to limit the extent of angular rotation of the adjustment ring 126, the adjustment ring 126 is formed with a ta 182 which extends toward, but terminates before, the beveled annular surface 176, as is best shown in Figure 1. The projections 164,166 of the stop rings 156 extend beyond the V-shaped annular groove and therefore extend into the path of travel of the tab 182. Thus, the range of angular rotation of the adjustment ring 126 is limited by the angular positions of the stop rings 156.
In operation of the limit stop arrangement just described, the stop rings 156 are set with their first barbs 172 engaging the adjustment projections 166 so that the circumferences of the stop rings 156 are relatively large and the stop rings 156 are free to rotate independently in the V-shaped annular groove. The operator then sets the greater of the two preset depths of cut. The lower stop ring 156 is then moved so that its interfering projection 164 abuts the tab 182. The adjustment tab 170 is then manipulated so that the second barb 174 engages the adjustment projection 166 of the lower stop ring 156. This causes the lower stop ring 156 to be clamped to the base 108 by means of the ribs 180 and the serration grooves 160. Next, the adjustment ring 126 is moved to set the shallower depth of cut. The upper stop ring 156 is then moved so that its interfering projection 164 abuts the tab 182. Its adjustment tab 170 is then manipulated so that the second barb 174 engages the adjustment projection 166. This clamps the upper stop ring 156 to the lower stop ring 156 by means of the serrations on the end surfaces 162. Thereafter, the operator can quickly change the depth of cut between the preset deeper and shallower depths of cut, as defined by the positions of the two
stop rings 156, by rotating the adjustment ring 126 until the tab 182 abuts against the respective interfer¬ ing projection 164.
Accordingly, there has been disclosed an improved depth of cut adjustment mechanism for a router. While an exemplary embodiment has been disclosed herein, it will be appreciated by those skilled in the art that various modifications and adaptations to the disclosed embodiment may be made and it is only intended that this invention be limited by the scope of the appended claims.