Inch shaft collars by bore: outside diameter, width and screw size for set screw, one-piece clamp and two-piece clamp collars.
A shaft collar is a ring that locks onto a round shaft to make a stop or a shoulder: it holds a bearing, gear, sprocket or wheel in place, or spaces parts apart. A set screw collar is held by a set screw tightened onto the shaft. A one-piece clamp collar is split on one side and pinched tight by a cap screw across the split. A two-piece clamp collar is two halves held by two screws, so it goes on or off without sliding it over the end of the shaft. Each is sized by the bore, the shaft it fits.
Jump to: Set screw · One-piece clamp · Two-piece clamp
| Bore | OD | Width | Set screw |
|---|---|---|---|
| 3/16″ | 7/16″ | 1/4″ | 8-32 × 1/8″ |
| 1/4″ | 1/2″ | — | — |
| 5/16″ | 5/8″ | — | 10-32 × — |
| 3/8″ | 3/4″ | 3/8″ | 1/4-20 × 3/16″ |
| 7/16″ | 7/8″ | 7/16″ | 1/4-20 × 1/4″ |
| 1/2″ | 1″ | 7/16″ | 1/4-20 × 1/4″ |
| 9/16″ | 1″ | 7/16″ | 1/4-20 × 1/4″ |
| 5/8″ | 1-1/8″ | 1/2″ | 5/16-18 × 1/4″ |
| 11/16″ | 1-1/4″ | 9/16″ | 5/16-18 × 1/4″ |
| 3/4″ | 1-1/4″ | 9/16″ | 5/16-18 × 1/4″ |
| 13/16″ | — | 9/16″ | 5/16-18 × 1/4″ |
| 7/8″ | 1-1/2″ | 9/16″ | 5/16-18 × 5/16″ |
| 15/16″ | — | 9/16″ | — |
| 1″ | — | 5/8″ | — |
| 1-1/16″ | 1-3/4″ | 5/8″ | 5/16-18 × 5/16″ |
| 1-1/8″ | 1-3/4″ | 5/8″ | 5/16-18 × 5/16″ |
| 1-3/16″ | 2″ | 11/16″ | 3/8-16 × 3/8″ |
| 1-1/4″ | 2″ | 11/16″ | 3/8-16 × 3/8″ |
| 1-5/16″ | 2-1/8″ | 11/16″ | 3/8-16 × 3/8″ |
| 1-3/8″ | 2-1/8″ | 3/4″ | 3/8-16 × 3/8″ |
| 1-7/16″ | 2-1/4″ | 3/4″ | 3/8-16 × 3/8″ |
| 1-1/2″ | 2-1/4″ | 3/4″ | 3/8-16 × 3/8″ |
| 1-5/8″ | 2-1/2″ | 13/16″ | 3/8-16 × 3/8″ |
| 1-3/4″ | — | 7/8″ | 1/2-13 × 1/2″ |
| 1-15/16″ | 3″ | 7/8″ | 1/2-13 × 1/2″ |
| 2″ | 3″ | 7/8″ | 1/2-13 × 1/2″ |
| 2-1/16″ | 3″ | 7/8″ | 1/2-13 × 1/2″ |
| 2-1/8″ | 3″ | 7/8″ | 1/2-13 × 1/2″ |
| 2-1/4″ | 3-1/4″ | 15/16″ | 1/2-13 × 1/2″ |
| 2-3/8″ | 3-1/4″ | 15/16″ | 1/2-13 × 1/2″ |
| 2-7/16″ | 3-1/2″ | 1″ | 1/2-13 × 1/2″ |
| 2-1/2″ | 3-1/2″ | 1″ | 1/2-13 × 1/2″ |
| 2-3/4″ | 4″ | 1-1/8″ | 1/2-13 × — |
| 2-15/16″ | — | 1-1/8″ | 1/2-13 × — |
| 3″ | — | 1-1/8″ | 1/2-13 × — |
| 3-7/16″ | — | 1-1/8″ | 1/2-13 × — |
| 3-1/2″ | 4-3/4″ | 1-1/8″ | 1/2-13 × — |
| 3-15/16″ | — | 1-1/8″ | 1/2-13 × — |
| 4″ | — | 1-1/8″ | 1/2-13 × — |
| Bore | OD | Width | Screw |
|---|---|---|---|
| 1/8″ | — | — | 4-40 |
| 3/16″ | — | — | 4-40 |
| 1/4″ | — | — | 4-40 |
| 5/16″ | 11/16″ | — | 4-40 |
| 3/8″ | 7/8″ | — | 6-32 |
| 7/16″ | 15/16″ | — | 6-32 |
| 1/2″ | 1-1/8″ | 13/32″ | 8-32 |
| 9/16″ | — | 7/16″ | 10-32 |
| 5/8″ | 1-5/16″ | 7/16″ | 10-32 |
| 11/16″ | — | — | 10-32 |
| 3/4″ | 1-1/2″ | 1/2″ | 1/4-28 |
| 13/16″ | 1-5/8″ | 1/2″ | 1/4-28 |
| 7/8″ | 1-5/8″ | 1/2″ | 1/4-28 |
| 15/16″ | 1-3/4″ | 1/2″ | 1/4-28 |
| 1″ | 1-3/4″ | 1/2″ | 1/4-28 |
| 1-1/16″ | 1-7/8″ | 1/2″ | 1/4-28 |
| 1-1/8″ | 1-7/8″ | 1/2″ | 1/4-28 |
| 1-3/16″ | 2-1/16″ | 1/2″ | 1/4-28 |
| 1-1/4″ | 2-1/16″ | 1/2″ | 1/4-28 |
| 1-5/16″ | — | 9/16″ | 1/4-28 |
| 1-3/8″ | 2-1/4″ | 9/16″ | 1/4-28 |
| 1-7/16″ | 2-1/4″ | 9/16″ | 1/4-28 |
| 1-1/2″ | 2-3/8″ | 9/16″ | 1/4-28 |
| 1-9/16″ | 2-3/8″ | 9/16″ | 1/4-28 |
| 1-5/8″ | 2-5/8″ | 11/16″ | 5/16-24 |
| 1-11/16″ | 2-3/4″ | 11/16″ | 5/16-24 |
| 1-3/4″ | 2-3/4″ | 11/16″ | 5/16-24 |
| 1-13/16″ | 2-7/8″ | 11/16″ | 5/16-24 |
| 1-7/8″ | 2-7/8″ | 11/16″ | 5/16-24 |
| 1-15/16″ | 3″ | 11/16″ | 5/16-24 |
| 2″ | 3″ | 11/16″ | 5/16-24 |
| 2-1/16″ | — | 3/4″ | 5/16-24 |
| 2-1/8″ | 3-1/4″ | 3/4″ | 5/16-24 |
| 2-3/16″ | 3-1/4″ | 3/4″ | 5/16-24 |
| 2-1/4″ | 3-1/4″ | 3/4″ | 5/16-24 |
| 2-5/16″ | — | 3/4″ | 5/16-24 |
| 2-3/8″ | 3-1/2″ | 3/4″ | 5/16-24 |
| 2-7/16″ | 3-1/2″ | 3/4″ | 5/16-24 |
| 2-1/2″ | 3-3/4″ | 7/8″ | 3/8-24 |
| 2-9/16″ | 3-7/8″ | 7/8″ | 3/8-24 |
| 2-5/8″ | 3-7/8″ | 7/8″ | 3/8-24 |
| 2-11/16″ | 4″ | 7/8″ | 3/8-24 |
| 2-3/4″ | 4″ | 7/8″ | 3/8-24 |
| 2-13/16″ | 4-1/4″ | 7/8″ | 3/8-24 |
| 2-7/8″ | 4-1/4″ | 7/8″ | 3/8-24 |
| 2-15/16″ | 4-1/4″ | 7/8″ | 3/8-24 |
| 3″ | 4-1/4″ | 7/8″ | 3/8-24 |
| Bore | OD | Width | Screw |
|---|---|---|---|
| 1/8″ | — | — | 4-40 |
| 3/16″ | — | — | 4-40 |
| 1/4″ | — | — | 4-40 |
| 5/16″ | 11/16″ | — | 4-40 |
| 3/8″ | 7/8″ | — | 6-32 |
| 7/16″ | 15/16″ | — | 6-32 |
| 1/2″ | 1-1/8″ | 13/32″ | 8-32 |
| 9/16″ | — | 7/16″ | 10-32 |
| 5/8″ | 1-5/16″ | 7/16″ | 10-32 |
| 11/16″ | — | — | 10-32 |
| 3/4″ | 1-1/2″ | 1/2″ | 1/4-28 |
| 13/16″ | 1-5/8″ | 1/2″ | 1/4-28 |
| 7/8″ | 1-5/8″ | 1/2″ | 1/4-28 |
| 15/16″ | 1-3/4″ | 1/2″ | 1/4-28 |
| 1″ | 1-3/4″ | 1/2″ | 1/4-28 |
| 1-1/16″ | 1-7/8″ | 1/2″ | 1/4-28 |
| 1-1/8″ | 1-7/8″ | 1/2″ | 1/4-28 |
| 1-3/16″ | 2-1/16″ | 1/2″ | 1/4-28 |
| 1-1/4″ | 2-1/16″ | 1/2″ | 1/4-28 |
| 1-5/16″ | — | 9/16″ | 1/4-28 |
| 1-3/8″ | 2-1/4″ | 9/16″ | 1/4-28 |
| 1-7/16″ | 2-1/4″ | 9/16″ | 1/4-28 |
| 1-1/2″ | 2-3/8″ | 9/16″ | 1/4-28 |
| 1-9/16″ | 2-3/8″ | 9/16″ | 1/4-28 |
| 1-5/8″ | 2-5/8″ | 11/16″ | 5/16-24 |
| 1-11/16″ | 2-3/4″ | 11/16″ | 5/16-24 |
| 1-3/4″ | 2-3/4″ | 11/16″ | 5/16-24 |
| 1-13/16″ | 2-7/8″ | 11/16″ | 5/16-24 |
| 1-7/8″ | 2-7/8″ | 11/16″ | 5/16-24 |
| 1-15/16″ | 3″ | 11/16″ | 5/16-24 |
| 2″ | 3″ | 11/16″ | 5/16-24 |
| 2-1/16″ | — | 3/4″ | 5/16-24 |
| 2-1/8″ | 3-1/4″ | 3/4″ | 5/16-24 |
| 2-3/16″ | 3-1/4″ | 3/4″ | 5/16-24 |
| 2-1/4″ | 3-1/4″ | 3/4″ | 5/16-24 |
| 2-5/16″ | — | 3/4″ | 5/16-24 |
| 2-3/8″ | 3-1/2″ | 3/4″ | 5/16-24 |
| 2-7/16″ | 3-1/2″ | 3/4″ | 5/16-24 |
| 2-1/2″ | 3-3/4″ | 7/8″ | 3/8-24 |
| 2-9/16″ | 3-7/8″ | 7/8″ | 3/8-24 |
| 2-5/8″ | 3-7/8″ | 7/8″ | 3/8-24 |
| 2-11/16″ | 4″ | 7/8″ | 3/8-24 |
| 2-3/4″ | 4″ | 7/8″ | 3/8-24 |
| 2-13/16″ | 4-1/4″ | 7/8″ | 3/8-24 |
| 2-7/8″ | 4-1/4″ | 7/8″ | 3/8-24 |
| 2-15/16″ | 4-1/4″ | 7/8″ | 3/8-24 |
| 3″ | 4-1/4″ | 7/8″ | 3/8-24 |
Good to know
Order by the bore. There is no national standard for shaft collars: each maker publishes its own outside diameter and width, and they don’t always match. Our chart prints the sizes two makers (Climax and Ruland) both list; where they differ it shows a dash rather than pick one. When a collar has to fit a tight space, measure the one in hand.
Holding power isn’t on our chart. Each maker rates its own collars (screw, seating torque and shaft hardness all change it). Set screw collars grip best on a shaft softer than the screw; on a hardened shaft use a clamp collar. For a critical load, use the maker’s rating for the exact part.
Quick answers
- What size is a 1/2 inch shaft collar?
- A 1/2″ set screw collar is 1″ outside diameter and 7/16″ wide, with a 1/4-20 × 1/4″ set screw (Climax and Ruland list the same).
- What are the dimensions of a 1 inch clamp collar?
- A 1″ one-piece clamp collar: 1-3/4″ OD, 1/2″ wide, one 1/4-28 clamp screw.
- What size is a 3/4 inch two-piece shaft collar?
- A 3/4″ two-piece clamp collar: 1-1/2″ OD, 1/2″ wide, two 1/4-28 screws (one each side).
- What is the difference between a set screw collar and a clamp collar?
- A set screw collar is held by a screw pressing on the shaft; a clamp collar (one-piece split or two-piece) squeezes all the way around and does not mark the shaft. Clamp collars are the choice on hardened shafts.
- How do you measure a shaft collar?
- By its bore, the shaft it fits: a 1/2″ collar goes on a 1/2″ shaft. Outside diameter and width vary by maker; this chart shows them where two makers agree.