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Collets don’t fit - others do

m.meuweae

Plastic
Joined
Mar 22, 2022
My first post as I just became the owner of an Aciera f3 milling machine. It needs repairs and restoration to some degree.

After assessing the machine I noticed that the collets don’t fit and bind when inserting them. Initial thought was a bur somewhere hence I cleaned the inside, collets and checked the spline in the chuck and that seemed all smooth and clean.

Hence I checked a few collets I had and some slide in just fine whereas others bind, including new once.

When painting the collet keyway and inserting it until it binds shows that the spline inside the chuck rubs against the collet keyway bottom. Like it is to large … width of the spline seems not the issue as the collet that fits has a narrower key way then the ones that do not.

What could be the problem?
Can I cleanup the spline with a small file / diamond stone?
 
There are a lot of choices in collets in reference to quality, I would make sure you in fact have top quality examples before changing anything.
 
Might be good to check all the key slots with jo block 0r made-up gauge.
Gong tight near the far inside end of the key slot, the may be sprung

We used to make a project of deburring new collets, even the best name brands would often need deburring.
 
I am with "Kustomizer" on the collets...
The machine is likely a better standard than a group of random collets....
I would look to modify or "Tune" up the collets before doing anything to the machine....

If the key ways on the offending collets are too shallow,(verify with actual measurements) a little work with a small carbide end mill will put it right.....
You have the mill, time to put it to work...
Better yet look for some good quality collets..here,I would be looking at a set made by Schaublin....
Cheers Ross
 
These won't be random brands, I think Schaublin was/is the only maker of w12 collets. They should measure about 11.99 on the body; the bore in the machine will be spot on 12mm. Any little burr or bruise on the collet, usually around the slot, will make them difficult to impossible to fit in the spindle.

If indeed the key in the spindle is too long, which would be odd, it's fine to reduce it a bit with a small file.
 
These won't be random brands, I think Schaublin was/is the only maker of w12 collets. They should measure about 11.99 on the body; the bore in the machine will be spot on 12mm. Any little burr or bruise on the collet, usually around the slot, will make them difficult to impossible to fit in the spindle.

If indeed the key in the spindle is too long, which would be odd, it's fine to reduce it a bit with a small file.

Aciera F3 has W20 collets

Peter
 
My Studer grinder takes W20 and W25 collets, and the clearances are very tight. Screwmachine is right on target, even a small burr or bruise will prevent the collet from fitting in place. So use a small stone to clean up the slot and if needed the cylindrical body of the "bad" collets, and they will probably slide right in.
 
Better yet look for some good quality collets..here,I would be looking at a set made by Schaublin....
Cheers Ross

I've always thought about those but 1) don't want another mortgage on the house, and 2) I'd rather have the Vincent Black Shadow instead, same money....

:)

And yes, blue the sticky collet with a sharpie and see where the intererence is. Remove interference.
 
Fixed binding collet issue

Okay, first and easiest test was blue dying a collet which binds and insert it in the spindle. Clear marks on the back of the collet and in the keyway. Tested others only blueing the keyway and concluded it must have a high point.

With some reluctance I took my smallest file and filled down the high point ever so slightly. Maybe 5 light passes until the surface had a nice shine to it. Cleaned out the spindle and - succes! All collets slide in nicely. Some are still a bit snug but that probably shall ware away when using this machine again.

Sad story is that I had to turn the head 90
Degrees to look into the spindle. Now I have to square it again with the table …

Thx for the advice.
 








 
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