Boring out an "emergency" 5C collet

[joahmon]

I know about the pins, etc. but wnat about the slits? Do I start with a drill or find/make a small boring tool to start?

oops, sorry, the hole will be 10 mm.

[precisionworks]

You'll need a hole that is somewhat undersized to start the boring bar. Since you want to finish at 0.3937" , a 5/16" or 11/32" drill will make a pilot hole with enough left to bore to size.

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Barry Milton

[joahmon]

Bary,
Thanks. I've never drilled into anything with slits before. Any advice??
Bob

[precisionworks]

Bob,

A hex or square collet block is one way to fixture for drilling & boring. It gives the collet head good support.

If you have a collet chuck in the lathe that is the easiest & best way to drill & bore. The emergency collets are dead soft and machine easily with HSS or carbide tooling. The slots shouldn't cause a problem.

[wierdscience]

Some are leadaloy,some are cold rolled and some are toolsteel in case you want to harden them.

Me I take no chances,I ditch the pins,and insert strips of sheetmetal to bore through instead.Just makes things go easier.