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Rack-and-Pinion Router With a Zero-Set Knob: Two Knobs on One Hollow Pinion, Set to Zero on the Work (Rees, 1969)
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13. November 2026NO
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Rack-and-Pinion Router With a Zero-Set Knob: Two Knobs on One Hollow Pinion, Set to Zero on the Work (Rees, 1969)

Spencer C. Rees of Pickens, South Carolina, received US 3,466,973, dated 16 September 1969, for The Singer Company. A rack screwed to the motor housing is moved by a pinion through a window in a box on the base. The pinion is a hollow shaft running in one bore through the box's two side lugs, with a knob at each end. One knob turns it. The other, a zero-set knob with graduations, slips on its sleeve against an O-ring, so it can be set to zero with the bit touching the work. One screw through the middle holds it all together. Only the pinion shaft was metal; the rest was moulded. We print every part in PETG round a small DC motor. The sizes are ours.
Advanced
About 3 days

Instructions

1

What one turn of the knob does

Loading Jupyter Notebook...
2

Read US 3,466,973

"The zero-set knob 40 has a reduced diameter portion 51 which carries circumferentially-spaced graduation marks 52 on its surface." "In the above-described structure it will be noted that the only metallic part required is the pinion shaft 37 which is a relatively simple two-diameter piece."
3

Print the base

The base 10: the split ring with clamp lugs, the box 28 for the rack with its two lugs 50 and stepped bore 33, the window 36, two legs 11 down to the plate 12 with its aperture, and two handle arms. Print it plate down. PETG, 0.2 mm layers, 40 % infill, 5 walls.
Design FileSTLCC0 - Free
4

Print the motor housing

The housing 19: a tube for a 42 mm motor, 56 mm outside, a ledge with an 18 mm hole and two M4 holes, and two M3 holes for the rack. Print it ledge down. PETG, 0.2 mm layers, 40 % infill, 5 walls.
Design FileSTLCC0 - Free
5

Print the small parts

One plate: the rack 29 (module 1.5), the hollow pinion shaft 37 with its toothed (splined) part, bearing part and end ribs, the adjusting knob 38 with grooves, the flanged sleeve 39, the zero-set knob 40 with 20 graduations and an O-ring groove, and the cover plate 53 with its window 55 and mark 56. PETG, 0.2 mm layers, 40 % infill, 5 walls.
Design FileSTLCC0 - Free
6

Motor in the housing

Fit the collet adapter on the motor's shaft, stand the motor in the housing on its ledge and screw it down with two M4 screws; wire it through a toggle switch to the DC supply. Screw the rack to the housing's front with two M3 screws.

Materials for this step:

PETG FilamentPETG Filament1 piece
Electric MotorElectric Motor1 piece
Motor Shaft Collet AdapterMotor Shaft Collet Adapter1 piece
Socket Head Cap ScrewSocket Head Cap Screw2 pieces
Machine ScrewsMachine Screws2 pieces
Toggle SwitchToggle Switch1 piece
Hook-Up WireHook-Up Wire1 piece
Heat Shrink TubingHeat Shrink Tubing1 piece

Tools needed:

FDM 3D PrinterFDM 3D Printer
DC Power SupplyDC Power Supply
Electric Soldering IronElectric Soldering Iron
Hex Key SetHex Key Set
Screwdriver SetScrewdriver Set
Deburring ToolDeburring Tool
7

Base and handles

Turn two hardwood handles 17 and bolt one to each arm with an M8 bolt. Slide the housing into the base with the rack in the box's channel, and put an M5 screw with a wing nut through the clamp lugs.

Materials for this step:

Hardwood BoardHardwood Board1 piece
Hex Bolt AssortmentHex Bolt Assortment2 pieces
Hex NutHex Nut3 pieces
Socket Head Cap ScrewSocket Head Cap Screw1 piece
Wing NutWing Nut1 piece

Tools needed:

Wood LatheWood Lathe
Cordless DrillCordless Drill
Drill Bit SetDrill Bit Set
Adjustable SpannerAdjustable Spanner
8

Pinion, knobs and cover

Push the pinion shaft through the box's bore from the right, its toothed part through the window meshing with the rack, its bearing part in the right lug. Fit the O-ring in the zero-set knob's groove, push the sleeve into the knob, and slide them onto the shaft's toothed end from the left, the sleeve in the left lug. Fit the adjusting knob on the right end, its grooves on the shaft's ribs. Pass a long M4 screw through knob, shaft and sleeve with a washer, into a nut in the sleeve, and tighten it until the knobs have only a little end play. Screw the cover over the box with two M3 screws.

Materials for this step:

O-RingO-Ring1 piece
Socket Head Cap ScrewSocket Head Cap Screw1 piece
Flat WasherFlat Washer1 piece
Hex NutHex Nut1 piece
Machine ScrewsMachine Screws2 pieces

Tools needed:

Hex Key SetHex Key Set
Screwdriver SetScrewdriver Set
9

Set zero and rout

Fit a bit. Loosen the clamp, turn the adjusting knob until the bit's tip touches the work, then turn the zero-set knob alone until its zero lines up with the cover's mark. Turn the adjusting knob to the depth wanted, read off the graduations, and clamp. Rout with both hands on the handles.

Tools needed:

Router Bit SetRouter Bit Set
Hardwood BoardHardwood Board
Bar ClampBar Clamp
Digital Caliper 6-InchDigital Caliper 6-Inch
Safety GlassesSafety Glasses
10

Troubleshooting

Rack and pinion router troubleshooting.

Flow

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11

History and honest limits

**Spencer C. Rees** of Pickens, South Carolina, assignor to The Singer Company, US 3,466,973, dated 16 September 1969, filed 8 January 1968. He claimed a rack on the motor housing, "a pair of lugs formed on the base in fixed spaced relation on opposite sides of the rack and having aligned cylindrical apertures", a hollow pinion shaft, an adjusting knob, a flanged sleeve, "a zero-set knob frictionally coupled to said sleeve", and "single fastening means" through them all. His pinion shaft was metal and the rest moulded; ours is all printed. His motor ran on mains; ours is a small DC motor. He gives no sizes; every size here is ours.

Materials

14

Tools Required

15

Design Files

3

This blueprint makes

CC0 Public Domain

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