US 3466973 A
Description (OCR text may contain errors)
Sept. 16, 1969 s. c. REEs 3,466,973
RACK AND PINION DEPTH-OF-CUT ADJUSTING MECHANISM FOR PORTABLE' ROUTERS Filed Jan. 8, 1968 2 Sheets-Sheet 1 INVENTOR.
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RACK AND PINION DEPTH-OF-CUT ADJUSTING MECHANISM FOR PORTABLE ROUTERS Filed Jan. 8, 1968 2 Sheets-Sheet 2 INVENTOR. N@ Spencer C. Rees v r Witness BY I I Y E l g @sulla Tf- ATTORNEY United States Patent Oliice 3,466,973 Patented Sept. 16, 1969 3,466,973 RACK AND PINION DEPTH-OF-CUT ADJUSTING MECHANISM FOR PORTABLE ROUTERS Spencer C. Rees, Pickens, S.C., assignor to The Singer Company, New York, N..Y., a corporation of New Jersey Filed Jan. 8, 1968, Ser. No. 696,451 Int. Cl. B23c 1/20; B27e 5/10 U.S. CI. 90--12 3 Claims ABSTRACT F THE DISCLOSURE An adjusting mechanism for portable routers combines two knobs equally accessible and positioned in spaced relation on opposite sides of a rack and operatively asso ciated with a hollow shaft carrying a pinion for moving the rack. One knob is locked for rotation with the shaft and the other kno-b is frictionally coupled to the shaft. A single metal part is required which is simple in form and the more complex parts are formed by molding to provide a low-cost easy assembly secured by a single fastening element.
Background of the invention This invention relates to rack and pinion depth-of-cut adjusting mechanisms for portable routers and more specifically to such mechanisms which incorporate a zeroset feature to facilitate the adjustment.
Accordingly one object of this invention is to provide a zero-set knob removed from adjacency with respect to the depth-of-cut adjusting knob and of a relative size to be as readily accessible as the adjusting knob itself.
A further object of this invention is to provide a pinion assembly for a depth-of-cut adjusting mechanism which yrequires a minimum of simple metallic parts, the major portion of the mechanism being adapted for fabrication by molding from inexepensive non-metallic materials.
Another object of this invention is to provide a pinion shaft which is journaled in a single through bore made in relatively rigidly fixe-d lugs spaced on opposite sides of the rack with which the pinion meshes.
These and other objects of the present invention will become apparent from a reading of the following specification taken in conjunction with the drawings.
Brief description of the drawings FIG. 1 is a front elevation view of a portable electricy Description of a preferred embodiment Referring now to FIG. 1, a portable electric router is shown having a stationary base of generally hollow cylindrical form. The base 10 is formed with two downwardly extending diametrically opposed leg portions 11 11 which are joined by a flat flanged portion 12 which is adapted to contact the work itself or to receive a nonmetallic sub-base 13 suitable for sliding over the work. This structure provides a large aperture 14 through which to observe the cutting of the work by a suitable tool bit (not shown) secured in a collet 15 by a nut 16.
Handles 17-17 secured to the leg Iportions 11-11 facilitate the manual guiding of the tool over the Work and one handle contains a switch (not shown) having an actuator button 18 conveniently located for control of power to the tool bit.
A motor housing 19 for supporting electric motor structure (not shown) is adapted to telescope within the base 10 for vertical sliding motion relative thereto. An insulated end cover 20 surmounts the motor housing 19 and is adapted to receive a power cord 21 and a switch cable 22 for electrical connection to the switch (not shown) housed within the handle 17.
Referring more specifically to FIG. 2, the base 10` is split or slotted as indicated at 23 and is provided with springing lugs 24-25 on either side of the slot 23. A clamping screw 2S extends through apertures in the lugs 24 24 to engage a nut 26 and serves to provide means for clamping the motor housing 19 within the base 10 in any selected relative axial position of the parts.
A housing skirt 27 made of sheet steel is secured to the exterior of housing 19 to provide a smooth wear-resistant sliding surface between the parts. It will be understood that a conventional electric motor contained vertically within housing 19 has its output shaft directly connected to the collet or chuck 1S for driving a tool bit.
The structure, as thus far described, forms no part of the present invention and there will now be described specific structure for adjusting the housing 19 relative to the base 10, which structure is believed to be novel in this art.
Referring more specifically to FIG. 3, the base 10 is formed with a radially-offset portion 28 adapted to provide a slidable housing for a rack member 29 which is secured to the housing 19 by means of tap screws 30-30. The rack-receiving portion 28 is an open-ended box-like structure having a front wall 31 and side walls 32-32. Thickened portions 50-50 of the side walls 32-32. provide lugs spaced in fixed relation on opposite sides of the 'rack 29. A single bore 33 extends through the lugs 50'-50 and provides spaced bearing seats 34, 35 therein. The single bore 33 also removes part of the front Wall 31 to leave a window 36 providing access to the rack 29 for driving engagement therewith by a pinion journaled in said bearing seats 34, 35 as will be described presently.
A pinion assembly comprises the following parts: a pinion shaft 37, an adjusting knob 38, a flanged sleeve 39, a zero set knob 40, a resilient O-ring 41, a screw 42, a washer 43 and a nut 44.
The pinion shaft 37 is hollow and is formed with a splined portion 45 and a smooth bearing portion 46. Radial ribs 47 formed on the end face of the pinion shaft 37 are adapted to drivingly engage radial grooves 48 formed in the adjusting knob 38 when the parts are in the assembled condition shown in FIG. 2.
The flanged 4sleeve 39 is nested within the zero-set knob 40 and is frictionally coupled thereto by means of a resilient O-ring 41 held captive and in compression between the two parts. Internal splines 4'9 formed on the sleeve 39 engage with the splined portion 45 of the pinion shaft 37 in assembled condition to lock the sleeve for rotation with the pinion shaft.
The single screw 42 is passed through the nested assembly of the parts as shown in FIG. 2 and is threaded into the nut 44 held nonturnable within sleeve 39 `with the pinion shaft 37 acting as a spacer to hold the knobs 3 38 and 40 in clamped relation with slight end-play with respect to the lugs 50-50. The bearing portion 46 is journaled in the seat 35 and the lianged sleeve 39 is journaled in the seat 34 and this structure provides automatic alignment of the parts inasmuch as the seats 34 and 3S are formed by a single boring operation.
The zero-set knob 40 has a reduced diameter portion 51 which carries circumferentially-spaced graduation marks 52 on its surface. A semicylindrical cover-plate 53 is secured to the front wall 31 by means of screws 54-54 and covers the pinion assembly permitting only the knurled portions of each of the knobs 38 and 40 to be exposed at each end thereof for manipulation. A window 55 formed in the cover-plate 53 is provided with a xed reference mark 56 to enable the graduation marks 52 to be viewed so that the zero-set knob Amay be selectively rotated to any desired initial annular index setting with respect to the angular position of the pinion shaft 37.
In the above-described structure it will be noted that the only metallic part required is the pinion vshaft 37 lwhich is a relatively simple two-diameter piece. All the other parts are readily formed by molding from nonmetallic and inexpensive materials. The assembly is simple, and requires but a simple conventional fastening element and results in an effective depth-of-cut adjusting mechanism having a distinctive quality appearance attainable at low cost.
Having thus set forth the nature of this invention, what I claim herein is:
1. In a portable electric router having a Work-engaging base, a motor housing axially adjustable therein and means for clamping the motor housing and base in selected relative axial positions; a depth-of-cut adjusting and calibration means comprising:
(a) a rack longitudinally secured on said motor hous- (b) a pair of lugs formed on the base in xed spaced relation on opposite sides of the rack and having aligned cylindrical apertures,
(c) a hollow pinion shaft carrying a pinion in engagement with the rack,
(d) opposite end portions of the pinion shaft extending through the aligned apertures,
(e) an adjusting knob carried on one end of the pinion shaft for rotation therewith,
(f) a sleeve having a flanged portion and carried on the other end of the pinion shaft for rotation therewith,
(g) said pinion shaft and said sleeve each having a bearing portion journaled in a respective lug aperture,
(h) a zero-set knob frictionally coupled to` said sleeve and retained thereon by the anged portion of said sleeve, and
'(i) single fastening means passing through said adjusting knob, said hollow pinion shaft and said sleeve to secure these parts in coupled relation for rotation as a unit.
2. Mechanism in accordance with claim 1, wherein the zero-set knob has circumferentially spaced graduation marks on a surface portion thereof and a cover-plate removably secured to the base has a window with a stationary index mark for visually setting said zero-set knob to align any one of said graduation marks with said reference mark.
3. Mechanism in accordance with claim 1, wherein a cover-plate removably secured to the base provides with said base a closure for the mechanism leaving the knobs exposed at each end substantially as a continuation of the cover.
References Cited UNITED STATES PATENTS 1,874,232 8/1932 Groene et al 90-12 2,855,963 10/1958 Potter 144-134 ANDREW R. IUHASZ, Primary Examiner G. WEIDENFELD, Assistant Examiner U.S. Cl. X.R. 144-l34, 136