Chuck
Glossary · Workholding & Setup
At a glance
- Category /
- Workholding & Setup
- Also called /
- three jaw, four jaw, soft jaws
- Related /
- 3 terms
- Source /
- Written in the shop
A chuck is the clamping device that grips a workpiece on a lathe, using jaws that move to centre and hold the part.
Also called: three jaw · four jaw · soft jaws
In practice
A three-jaw self-centres and is fast but not perfectly accurate. A four-jaw has independently adjustable jaws and can be indicated in precisely, or used to hold something that is not round. Soft jaws are machined in place to fit one part exactly.
Why it matters
How the part is gripped determines how true it runs and how much it distorts. Clamp a thin-walled part too hard in a three-jaw and it will machine perfectly round, then spring out of round the moment it is released.
Have a drawing with this on it?
Request a Quote
Send it over and we will tell you what it will take to hold — and what is safe to loosen.