Runout on a collet chuck?

[PeteParticipant @pete41194]

Posted by Robin on 15/09/2023 10:55:16:

Posted by Pete on 15/09/2023 03:56:15:

I have bought junk on occasion but hope springs eternal so it is easy to get caught out. Probably best not to risk buying a new set of ER40 collets then, unless I am feeling flush and can afford high-accuracy

Work holding is a bit different than using the same collets to mill with. As someone else already pointed out, buying better for the tool shank sizes most used on a mill might be a good idea. Although I also have a few pieces of what were quite cheap off shore tooling that surprisingly did meet the manufacturer's claims. So yes sometimes you can be lucky. As a work holder, ER collets would grip better than any chuck and not mark finished work. And at least for shorter work, if its fully machined at a single chucking, the less accurate can still work just as well. But so would just about any 3 jaw. To be honest, I think using ER collets as a work holder has become more common at the amateur level simply because more already have them for there mills and not because there aren't other methods that couldn't also be used. Afaik there never used as a work holding method in industry simply because there too slow to open and close. And there's better collet types and chucks designed for that exact purpose. One use where I would purposely choose an ER collet for over anything else I have would be holding thin wall parts or tubing.

[Andrew TinsleyParticipant @andrewtinsley63637]

I am sorry if my simple query has caused controversy. I have had only a little experience with ER collets and that was using a very high quality collet chuck and collets

I was thinking that it was better to get the best runout I could, on the inside of the collet chuck taper. My new collets are probably much worse than 1 thou runout (have yet to check!). That made me question why I was bothering making the collet chuck and buying collets, when I would normally use a 4 jaw chuck and set that up to a thou or less if I wanted good accuracy.

I suppose that it would give me speed of use, but then I am a slow worker and I simply enjoy what I do.. Made me think that I could have spent the cash more wisely.

Regards,

Andrew.

[Nick WheelerParticipant @nickwheeler]

Pete is partly right about using ER collets for workholding because they were already bought for holding cutters.

For me, the availability of hex and square collet blocks is a major reason for fitting the collect chuck to the lathe. Their use makes creating various flats, cross holes and the like much simpler.

[CirclipParticipant @circlip]

A perfectly good question Andrew and not controversial, just different opinions. OK, given a zero run out on O/Ds and bores of all collet parameters – perfection -now what? Can you ensure whatever dia. material, fits the bore, exactly? A few thou plus or minus change the run out rules so to introduce a further point of dispute, the only true type of collet is the 'Rubberflex' version, grips all diameters to the range of the collet.

Originally intended for mass production of components in industry as were QCTPs and Carbides with everything, the perception of 'essentials' seems to be dictated by the depth of ones pockets containing disposable income.

Len Sparey started a minor revolution.

Regards Ian

[SillyOldDufferModerator @sillyoldduffer]

Posted by Circlip on 16/09/2023 09:23:51:

A perfectly good question Andrew and not controversial, just different opinions…

Always useful to explore options. My ER collets are mostly used for tool-holding, but every so often they're good for work-holding as well. In my case, mostly when smallish round jobs are moved repeatedly between machines. I have an ER collet chuck for the lathe, and square and hexagonal Stevenson Collet blocks from ArcEuroTrade:

 

 

 

If I did a lot of collet work, I'd invest in a set of 5C collets.  They aren't restricted to round work only, and can grip shorter lengths.  (ER collets need an inch or so of round to grip on.)  ER and 5C both achieve low run-out.  5C are best for work-holding, but costly.  ER are are cheaper because they clamp over a wide range and can be used on both lathe and mill.   Which is most useful depends on the type of work being done, and in that sense run-out is secondary.

Dave

 

Edited By SillyOldDuffer on 16/09/2023 11:56:04

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