Posted by COLIN MARTIN 2 on 29/04/2022 17:31:12:
I remember now why I did not buy a collet chuck a couple of years ago, it was because the reviews of the cheap ones were so bad that I did not think that it was worth it. Has the accuracy improved now or are the cheap ones still wildly inaccurate?
Reports of wild inaccuracy may have been exaggerated at the time! If you're unlucky and buy an unacceptably bad dud collet chuck from a reputable UK supplier they will replace it. But bear in mind hobby tooling is made down to price and buy an industrial chuck if you really need guaranteed accuracy. Expect to pay serious money for it and make sure your pacemaker has a new battery before asking.
MT vs backplate: backplate wins in my opinion. The advantage of MT is that the chuck can be plugged in and out quickly, which matters little in my workshop. A major disadavantage of MT on hobby kit, whether a sloppy new hobby lathe or a bashed about oldster, is there's no adjustment. If there's run-out, you're stuck with it.
Although a backplate takes longer to install they can be adjusted to almost entirely eliminate runout. The method is to mount the backplate with the bolts hand tight and put a ground rod in a collet, Then turn the lathe by hand and measure the run-out with a dial-indicator. Any run-out can be tuned out by tapping the backplate gently sideways with a rubber mallet. Tighten the bolts when the dial-indicator confirms it's good enough.
Collets are excellent for maintaining concentrity when working extensively with round rods. But they're not as convenient as a 3-jaw chuck for general purpose work, or as good at holding odd shapes as a 4-jaw. (And 4-jaws can be tuned with a dial-indicator too.)
For what it's worth, roughly 80% of my turning is done in a 3-jaw. I use a 4-jaw for almost everything else, and the collet chuck only comes out for special occasions – lots of smallish round rods going in and out of the chuck repeatedly. For me, that's usually when making something delicate that frequently swaps between mill and lathe. When I need them, collets are wonderful, but I don't use them much. Depends on the workshop – they score high for clockmaking and similar.
Dave