Posted by Martin Kyte on 20/02/2017 15:43:12:
So my conclusion is if you want a cheap chuck go for an economy standard precision new one rather than a high end old one. You are unlikely to get the low run out that the high end one once had and the jaws will have seen some use to boot. With then new one at least the jaws should close parallel. I know you can always regrind but that will not put the wear back on the tenons and new jaws are expensive.
That said I pensioned off my old griptru by buying it a set of soft jaws. In addition I have a 2 independent four jaws, a self centering four jaw an a Super Precision Pratt Burnerd for Sundays.
regards Martin
Unless you know for certainty that it's good then yes, I can say I have experience of prestigious large chucks that well and truly had it at 0.2mm runout, and gave me a difference in 0.05mm in diameter every 5mm or so. Try making gauges out of that!
Luckily it wasn't my machine but it was an extremely good make of industrial lathe that had seen a thrashing over it's lifetime.
My own home lathe can certainly do better than that, but anyways, standard 3 jaw chuck for my £800 machine gives 0.03 runout on nominal bar stock.
May have not been all the old chucks fault but I can't imagine it helped matters.
C'est Incroyable!
Michael W
Edited By Michael-w on 20/02/2017 16:49:25