Making a custom collet

KeithB

Resident Half Fast Machinist
Ever so often a custom size collet is needed. Yesterday I needed a collet to hold some 13mm (.512") A2 rod stock. The vendor shipped it to me as 1/2" (NOT!) and I did not have a 13mm or even a 33/64" collet on hand. And of course no local vendor had one in stock, and I wanted to get the pieces done and not wait 3-4 days for the right collet to be shipped to me. I keep a few blank collets in stock. They have a 1/16" center hole predrilled and have three small pins in the face to keep the three petals of the collet apart. Just tighten it into the collet chuck and bore to size. When you are done just remove the pins. (I keep the pins, they can be reinserted and the collet can be rebored to a larger size.)

I drilled the collet to 3/16" then 7/16". and then did the final boring to size with carbide boring tool. The tool has a 3/8" shank and uses a carbide insert that is less than 1/4" from corner to corner. The blank collets are not hardened, but carbide works well and with a fine feed at high speed the interior finish is fine, little polishing needed.

I finished up the job last evening, the collet worked great.

These are so handy I just ordered three more from Shars, at $7.50 each they are a bargain.

The emergency collet being bored using a 3/8" diameter boring bar with an indexible carbide insert.
customcollet1.jpg

The finished collet, a chamfer at mouth makes inserting stock easier.
customcollet2.jpg
 

Pistolero

Well-Known Member
Vrey nice. I think I know what will be added to my next Shars order.

They are a really good tooling company, in my experience.

Bill