- Cast Iron Adapter Can Be Threaded to Fit Any Spindle Nose Thread
- 3/8″ Smooth Pilot Hole
- 4″ (100 mm) in Diameter and Has No Chuck Mounting Holes
- Use It for All 3″ and 4″ Chucks
- 55 mm Diameter Hub
Cast iron lathe chuck adapter can be threaded to fit any spindle nose thread. It has a 3/8″ smooth pilot hole.This adapter is 4″ (100 mm) in diameter and has no chuck mounting holes. Use it for all 3″ and 4″ chucks.
*NOTE* These adapters require machining on the lathe on which they will be used.
Instructions are included for final turning of the registration diameter on your lathe to ensure perfect concentricity.
| Nominal Size | 4″ |
| Outside Diameter | Ø 3.9″ (100 mm) |
| Thread | 10 mm Smooth Bore |
| Bolt Holes | None |
| Hub Diameter | Ø 2.2″ (56 mm) |
| Hub Length | Ø 0.9″ (24 mm) |
| Flange Thickness | Ø 0.6″ (16 mm) |
| Registration Boss | Ø 0.1″ (3 mm) |
| Registration Diameter | Ø 2.8″ (72 mm) |
![PROFRAME HELMET MATTE [BLK] L](https://www.bestfixhardwareus.com/wp-content/uploads/2026/09/proframe-helmet-matte-blk-l.webp)
