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One-Screw Two-Part Shaft Collar: Hooked Ends Reach Round the Shaft So the Halves Cannot Open (Grundy, 1907)
John R. Grundy · Public domain
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13. November 2026NO
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One-Screw Two-Part Shaft Collar: Hooked Ends Reach Round the Shaft So the Halves Cannot Open (Grundy, 1907)

John R. Grundy of Philadelphia received US 860,369, dated 16 July 1907, for a two-part collar held by a single screw, where earlier split collars needed two. The screw passes through one pair of ends, an overhang on one part lying over the other. At the opposite side a tongue on one part fits a recess in the other. Both of those ends reach round the shaft past the diameter under the screw. When the screw's point presses the shaft, they hook under it and cannot open. Each part goes onto the shaft from the side, so the shaft stays in its bearings. We cut the two parts from a turned brass ring with a piercing saw, from a full-size template. The patent gives no sizes; every size here is ours.
Advanced
About 2 days

Instructions

1

Why the hooks hold

Loading Jupyter Notebook...
2

Read US 860,369

"It is obvious that by using the single screw in place of a plurality of screws, as has hitherto been considered necessary, I am enabled to reduce the cost of the collar." "The parts of said collar are placed in position on the shaft by being moved toward it in radial planes."
3

Turn the ring

Grip 45 mm brass round bar in the 3-jaw chuck. Face it, turn it to 40 mm for 20 mm, centre-drill, drill through 15 mm and ream 16 mm. Part off 16 mm long and face the parted side.

Materials for this step:

Brass Round BarBrass Round Bar1 piece

Tools needed:

Metal LatheMetal Lathe
Lathe Chuck 3-JawLathe Chuck 3-Jaw
Lathe Cutting ToolLathe Cutting Tool
Center Drill SetCenter Drill Set
Drill Bit SetDrill Bit Set
ReamerReamer
Parting ToolParting Tool
Digital Caliper 6-InchDigital Caliper 6-Inch
Safety GlassesSafety Glasses
4

Print the cutting template

Full-size A4 template: the end view of the ring with the outlines of parts B and B', and the bottom of the ring seen from below with the tongue b' and cheeks a'. Print at 100 %; its 50 mm bar must measure 50 mm.
Design FilePDFCC0 - Free
Download Model
5

Cut the parts apart

Glue the end view on one end face of the ring, centred, and the strip on the outside at the bottom. Wax the blade. Top joint: hold the ring in soft jaws, face up, and saw with the blade along the axis: in from the outside 5 mm left of the line to 14 mm radius, round the 14 mm circle to the line, and down the line into the bore. Bottom joint: turn the ring over and saw with the blade across the wall, following the strip from one end face to the other: the cheeks a' 3 mm left of the line, the tongue b' 3 mm right of it. Go slowly at the corners; the two parts come apart.

Tools needed:

Inkjet PrinterInkjet Printer
GlueGlue
Bench ViseBench Vise
Vice Soft JawsVice Soft Jaws
Jeweler's SawJeweler's Saw
BeeswaxBeeswax
6

Fit the joints and cut away the bores

File the saw marks off the joints until the tongue slides into its recess and the overhang lies on the other part, with the two parts round a 16 mm bar. File each part's bore out to 18 mm across over the 22 degrees next to the top joint on its own side, B' to the left of the line and B to the right, as the template shows. Try them on the bar: put B on from below right, then B' from below left, sliding it up under the overhang and the tongue into its recess. File until each goes on without forcing.

Tools needed:

Mild Steel Round BarMild Steel Round Bar
Bench ViseBench Vise
Vice Soft JawsVice Soft Jaws
File SetFile Set
Needle File SetNeedle File Set
Digital Caliper 6-InchDigital Caliper 6-Inch
7

Drill and tap for the screw

With both parts on the bar, the overhang lying on B', clamp the bar in the machine vice so the dashed screw line on the template stands upright. Drill 4.2 mm through the overhang and through B' into the bore, and tap M5 through both with cutting oil. Take the parts off and deburr the bore.

Materials for this step:

Cutting OilCutting Oil1 piece

Tools needed:

Mild Steel Round BarMild Steel Round Bar
Drill PressDrill Press
Machine ViceMachine Vice
Drill Bit SetDrill Bit Set
Tap and Die SetTap and Die Set
Tap WrenchTap Wrench
Deburring ToolDeburring Tool
8

The collar in 3D

FreeCAD model, our sizes: parts B and B' on a 16 mm shaft, the overhang b and the M5 screw at the top, the tongue b' between the cheeks a' at the bottom, and the bores cut away beside the top joint.
Design FileSTLCC0 - Free
Download Model
9

Fit it on the shaft

Run an M5 x 12 cup point set screw into the overhang until it just shows. Put B onto the shaft from the side where the collar is wanted, then B' from the other side, its top under the overhang and its tongue into the recess. Tighten the screw with the hex key: it pushes on the shaft and draws both bottom ends down against it. Try to slide and turn the collar; it must not move.

Materials for this step:

Cup Point Set ScrewCup Point Set Screw1 piece

Tools needed:

Hex Key SetHex Key Set
10

Troubleshooting

Grundy collar troubleshooting.

Flow

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11

History and honest limits

**John R. Grundy** of Philadelphia, US 860,369, dated 16 July 1907, filed 28 January 1907. He claimed "a shaft collar made in two parts, and means for holding the parts together comprising a single screw passing through two adjacent ends of said two parts, the other ends of said parts being formed to co-act with the shaft to prevent their separation". His screw end also has a second projection b2 in a recess, holding the parts in line along the shaft; ours leaves it out, as the screw through both parts does that. His screw has a hex head; ours is a socket set screw. He gives no material; ours is brass, which a piercing saw cuts well. The patent gives no sizes; every size here is ours.

Materials

3

Tools Required

24

Design Files

2

This blueprint makes

Thumbnail
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Shaft Collar

Free

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