5C round collets

[Metal Butcher]

Has any one out there purchased any Shars-brand 'round' 5c collets and checked them for run-out? I'm in need of a 7/32" and their offerings (on E-bay) are priced at $3.10 each. Since they are so low priced, I wonder if their any good.

I checked an older 5/16" Enco collet that I deemed bad (must have been swarf that threw the readings off), that was made in Taiwan, and it shows .0004 @ the face, and @ 1", and @ 2". That seems pretty good to me. And I just checked a recent Enco-MHC brand 3/32", and its showing .009 @ the face, and .005@ 1". Not good at all.

I just bought a 1/4" square collet from Shars and can't coment on the run-out without the use of a precision piece of 1/4" square stock, although its cosmetically as nice as any that I have seen. And it did the 'not so critical' job I bought it for well.

-MB

 

[Loose nut]

Cheap collets are always a crap shoot, some are great and some are crap. Unless you can afford to buy the good ones $$$$$$$$ then you have to take your chances. Most of the ones I have seem to be pretty good.

 

[Blogwitch]

I have used nothing but cheap 5C collets for years, two different full sets of collets on two different lathes and a few different chucks.

Once I reground the noses of the chucks to run true, up until now, all my collets, metric, imperial and square, all run true to the tolerance I expect of them, within 0.0005", most a lot less or even zero.

A lot of people blame their collets, when in fact, a lot of the time, it is the way the chuck has been mounted and trued up.


Bogs

 

[tomfilery]

John,

I have recently seen a post from you (possibly on another site - perish the thought) where you said something about you'd previously trued up around 5 collect chucks to match them to your lathe. In attempting to find your post, I came across this thread and so thought I'd ask my question:-

Can you please tell me what process you went through to get the collet chuck to run true?

I suspect that many others would find it helpful.

Kind regards Tom

 

[Blogwitch]

Tom,

Actually, I have done four of these cheap 5c collet chucks over the years, and every one of them was out when fitted to a dedicated backplate. A sad state of affairs, when people think it is the collets causing the problems, when it is in fact the chuck. That is why they are so cheap, they look great on the outside, all ground up and finished, but on the inside, that isn't normally seen, some of them are abysmal.

A lot of people go to great trouble to get their collet chucks to run true, from opening out the register on the back and making it a floating chuck that you attempt to get to run true by having adjusting screws to move it about the centre point, to all sorts of other tricks.

What a lot of people don't realise, that by having it floating, you are only taking out errors in one plane. What about if the centre hole isn't exactly square to the back of the chuck and so the spindle?
You can true that up first by mounting the chuck, using a collet with a bar in the nose and held in another chuck, and very gently regrind or fine turn the chuck back. I have done that only once, and it was an anal sphincter twitching exercise, and only got it close to being true, I still had to do a fine grind inside the nose.

All I can say, that if a collet chuck has a fairly small amount of runout (the worst of mine, IIRC, was 0.008" or 0.2mm), then by using the original register and fitting it well to a good quality backplate, then if you grind (or fine turn if the material is soft enough to do it) inside the nose, then it has to run perfectly true on the lathe it is ground or turned up on.

I have made other collet chucks and fittings for my lathe using the same method (not always grinding, I have turned a few as well), that final grind or fine cut, with the chuck in it's final resting place, guarantees success. Only then, once that is done, can you blame the collets.

I hope that explains well enough how I tackle the job. BTW, these cheap collet chucks aren't normally hardened, so if you can get a very sharp boring tool working, the job can easily be done by turning, just take great care you get your topslide set up for perfect angle fairly quickly, but you can skim a bit off the nose front if you go a bit deep. DAMHIK.

John

 

[tomfilery]

John,

Many thanks for your response. I don't yet have a collet chuck for my Myford S7 (so I'd be using a threaded, nose-mounted chuck, rather than one on a backplate), but am looking to get one - undoubtedly from RDG tools, or similar imported stock - and wanted to get a feel for what might be necessary to remove any inaccuracies.

I have to admit, this was in part, driven by a recent visit to a local supplier, who had customer-returned chucks at £10 each. Don't think I'd risk it, as there would be no chance of a return/ refund if it was out by miles!

I'd figured that with a very careful set up, it might be possible to re-bore the collet holder, were the material not too hard. What grinding set up did you use (if you don't mind me asking)?

I'm grateful for for you help and have to say I've thoroughly enjoyed some of your construction threads - your clarity of written style and provision of really good pictures sets an example many magazines would be advised to follow. Please continue in similar vein.

Regards Tom

 

[Blogwitch]

I don't really want to hijack MB's post much more, but just to answer your question, I use a Boxford 'Little Giant' toolpost grinder that I was given because the motor was burnt out, and I remotored it and made new cones to take account of the different speed of the new motor (I think the new runs at 14000, whereas the original turned at 16000 RPM).

I gather you will be buying an ER collet chuck for your Myford, because I don't think anyone makes a small screw on 5c collet chuck.

This is the part of a post where I do the nose of an ER chuck I made to fit a Myford nose. No grinder used on this one, just bored.

http://madmodder.net/index.php?topic=2249.msg23587#msg23587

If you want to see how I made the whole ER chuck, then go to the very start of the post.


John

 

[tomfilery]

John,

Sorry, yes I was looking at ER collects, not 5C - guess I should have tread the post title properly.

Don't think you need worry too much about hijacking the thread - it was started in Dec 2010 and been dormant since then.

Many thanks for the info - I'll look forward to reading your description.

Regards Tom