Help removing small parts from a threaded mandrel

SmokeWalker said:
I've got some 5/16 diameter plastic parts (which cannot be marred) to remove from a 5-40 threaded mandrel, and after they've been machined, they're kind of hard to remove.
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Get a scrap of aluminum plate, bore a 5//16 hole, and kerf cut the long way into the hole; that makes a U-shaped
gizmo that (with hand pressure) closes the kerf, and clamps the circular part HARD. Polish the edges...
Like these: <https://www.lazada.com.my/products/...-m3-m4-m5-m6-m7-mp-i484452919-s825702066.html>

It might not work (the part is plastic, so it might just deform enough to tighten). Actually, the earlier suggestion to heat it up seems good:
that'll loosen most plastic-around-metal combinations.
 
I'd suggest using a thin piece of leather between the pliers and the part. I keep several thicknesses of leather in the shop for just such a purpose. If you have a lot of parts to do, you can melt glue the leather to one or both jaws of the pliers, so you don't have to fight to keep everythnig aligned every time.
 
A picture of it might help better.


Flyinfool said:
Grab the parts in a collet to unscrew the mandrel? Then the collet should open enough to easily remove the part from there.
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I've done the same with collets or my 6-jaw chuck. The jaws on my 6-jaw chuck doesn't have bevels on the front edges of the jaws like 3-jaws typically do so I can grab a hold of really short parts.
 
You could go the overkill route and sacrifice a slip jaw pliers. I've welded a couple of pieces of 1/4" steel strap to each jaw, then set a piece of shim stock between the jaws and clamp tight in the mill vise. Hit it with a center-cutting 1/4" end mill for the initial hole, then follow up with a 5/16" end mill. You'd have a really quick collet to squeeze on 350+ deg. of the plastic part and break it free. But other suggestions above with a soft-jaw surface might work better.

Bruce
 
Without pictures I'm just guessing....

But I'd say heat is the answer here.

John
 
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