Totally useless 5C collets

[piper184]

Yup, DUH on me. For some reason my brain was stuck on ER collets.
Sorry for the confusion

 

[SLK001]

...I got a 50% refund so I have a bunch of $2 useless collets. Is there any way to bore out some of these collets to a good larger size?

You should have received a 100% refund. They will be hard, so use, or rig up a tool post grinder and grind out the bore so they run true. You'll need them tight in the collet closer, but not completely closed, so use the technique outlined in post #2.

It's really hard for me to imagine how they could have been this far off.

 

[sdelivery]

Usually the anti rotation pin in the chuck will prevent the collet being installed in other positions.

First thing broken on any bridgeport...

 

[mmcmdl]

First thing broken on any bridgeport...

First thing I always remove on a Bridgeport here .

 

[Uglydog]

If you do any Tig welding they might be helpful on set ups.
Perhaps close enough in collet blocks for a drill press.

Daryl
MN

 

[porthos]

whatever made you belive that chinese stuff has any degree of accuracy!

 

[WobblyHand]

whatever made you belive that chinese stuff has any degree of accuracy!

Part of the time it's ok, part of the time it's junk. There does seem to be a slight relationship with cost. If it seems unbelievably inexpensive to buy, there might be a reason. I own some Chinese made stuff, most of it is ok Also been burned on occasion. However, that's true of US sellers too. Since Roman times there's been a saying, caveat emptor, buyer beware. Nothing's changed in well over 2000 years.

 

[weston1968]

whatever made you belive that chinese stuff has any degree of accuracy!

I first purchased on eBay from a seller that sold 7 collets from a table of odd sized collets for $17. I bought 21 collets and checked about 5 and they were all good. I bought a 63/64" collet on Amazon from SARS (25mm use) and it was dead on. It looked like the Chinese now made good collets.

 

[weston1968]

Put something that you know is precision ground like drill rod or gauge pin in the collet. Make a witness mark on the pin, collet and holder. Check for run out and make a mark at the high spot.

Then loosen the collet and turn the stock 90 degrees. Re-tighten making sure the collet does not turn in the holder. Check run out again. Does the high spot move in relation to the collet or the holder? Make notes of how far out and what positions.

After you check it every 90 degrees, take it all apart and re-install it with all your original marks lined up to the same place. Check again. You should see the same run out that you first detected.

Next, go around again, this time rotating the collet in the holder but keeping the pin in the same place relative to the collet. Does the high spot stay with the mark on the collet or the holder?

This will show if the run out is in the internal bore or the external taper of the collet. It may be a combination of both.

Just as a sanity check, do the same test with a collet that shows no run out, just to confirm it is not the holder.

If the run out is in the bore, you may be able to true it up with a post grinder although that will change the size. Maybe you could make some metric collets out of them.

I'm not sure how to go about truing up the external taper but it could probably be done with a mandrel of some sort.

I could not rotate the collet, but I did mark the rod and rotate it. The error followed the collet. It is not the holder, I have other collets that are near perfect.

 

[wayback machine]

I've got a set of imperial 5C's I bought a couple years ago from Shars, to use in my Hardinge Cataract .
All of them dead nuts on, as far as I can tell.
YMMV