Had to pick between a 3-jaw chuck and a 4-jaw for a weird brass part today

So I got this job turning a tiny brass piece that was totally out of round. Real tough call. I went with the 4-jaw because I could adjust each jaw individually to center it up. Took me like 20 minutes to get it running true but after that the cut was perfect. Would a 3-jaw have worked faster? Maybe but I dont think it would have held that close. Has anyone else spent way too long dialing in a 4-jaw for a simple part?

2 comments

2 Comments

mitchell.thomas9d ago

My old mentor used to say a 4-jaw is for workholding and a 3-jaw is for speed, so you made the right call lol. I read in a trade magazine once that a 3-jaw can actually introduce runout on out-of-round stock by clamping unevenly. Twenty minutes dialing beats scrapping a part any day.

finley_smith9d ago

You said "twenty minutes dialing beats scrapping a part any day" but honestly how many parts are you really scrapping vs just wasting time setting up? I mean yeah runout is real but a 3-jaw works fine for 90% of jobs if you tap it in.