# Collet chuck



## don-tucker (Nov 20, 2009)

Just recieved a ER 25 collet chuck on a backplate,machined packplate register and face to a good fit in recess on chuck,bolted it on and checked, OD of chuck runs within 0.001" collet taper 0.025 run out, is this a record.I am so dissapointed, sent an e-mail to supplier but no answer yet.The collet thread is rough as a badgers bum.
Don


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## Blogwitch (Nov 20, 2009)

I have fitted a few of the Chinese 5C collet chucks.

The runout on the last one, fitted about 3 months ago was 0.008", and I have had worse than that.

They do look great, all ground up or chemi blacked, but that is all cosmetic, and people think that because they look good, they must be good. Far from it.

After getting the backplate machined up perfectly and the chuck fitted, I just mount up the toolpost grinder and everything is ground up to true within a few minutes.

You only get what you pay for. 100 UKP for a cheapo 5C chuck that has to be put right, or 400 UKP for a quality one that runs true from the off.

I have now decided it is easier to make my own ER collet chucks. You can then guarantee they are true to begin with. Just buy the collets and closer nut.

I know everyone won't have the facilities I have, so until you do, you will need to beg steal or borrow the bits needed to put them right.

If you have purchased one of these ER chucks, there is a way that you can use basic machinery to get them running true.

The attached C-o-C shows what is needed.

The stub in your chuck is machined up and NOT touched until the operation is of flange skimming is complete.

The recess and flange might only require a couple of thou to be skimmed off, but it must be done with razor sharp tooling, preferrably HSS.

Then machine up your backplate for a snug fit.

Unless you have grinding equipment, this is about the easiest way to true it all up. 

I have used this method to true up 3 jaw chucks to have a max of 0.0002" runout.


Blogs


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## don-tucker (Nov 20, 2009)

Thats not a bad idea,except the chuck body is hardened,If i'm stuck with it maybe I could try to true up the taper with a tip tool,but really speaking the chuck is not fit for purpose.
Don


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## cfellows (Nov 20, 2009)

Just received my ER40 - R8 collet chuck and 15 collets. I really only wanted the collets and the clamping nut, so the R8 chuck was a bonus. I haven't checked the runnout on it.

I'm planning to make a collet chuck for my Logan 11" lathe which has a 2.25 x 8 spindle. 

Chuck


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## don-tucker (Nov 20, 2009)

Bit the bullet and tried skimming the back of the chuck with a tip tool ,success,thanks Blogs.
Don


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## Artie (Nov 20, 2009)

HI Don, What was the outcome? Is the runout now within tolerances to your satisfaction?

Cheers

Artie


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## Blogwitch (Nov 20, 2009)

Don,

I hope it made a big difference to your accuracy. Was there much runout on the back face when you mounted it up?

I didn't realise you had a Myford.

I use a Myford nose converter for my lathe so that I can easily swap between lathe and RT with certain chucks and fittings.

http://madmodder.net/index.php?topic=1993.0

http://madmodder.net/index.php?topic=2002.0

I am just making my own ER 32 collet chuck that fits Myford threads. Very easily done if you can single point thread.


Chuck,

I have an ER32 R8 chuck for my mill, but I very rarely use it now. I found that it restricted the throat height a little too much, especially when using the RT with a chuck mounted, so I am now using R8 collets, truer running and tighter grip, plus a couple of inches gained in the throat department.

The ER chuck is soon to be limited to lathe and RT work.

Blogs


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## don-tucker (Nov 20, 2009)

I didn't check the runout but it was quite a bit,it runs about 0.002" out now,mainly due to the back plate register a bit on the big side but I can live with that.Unless you have an answer to that.I did think of making a chuck,but the cost of extra gears to cut metric wasn't worth it
Don


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## don-tucker (Nov 21, 2009)

Just sleeved the back plate and the runout is now 1/2 a thou,very happy with that.
Don


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