[TheForge] slitting and drifting help needed

[marc at ironringforge.com]

I think by slitting you lose length. A slit length is actually longer than the
hole diameter. You can calculate each side of the slit to be 1/2 the perimeter
of the circle, minus a little for the eventual "stretching" when 
drifting. When
you drift, the sides of the slit bump out to form the circle, and that 
will draw
the top and bottom of the slit together, making tyhe piece shorter.

A punch squishes the metal in all directions before the biscuit punches 
through,
and that would lengthen the piece.

--Marc

> -----Original Message-----
> From: theforge-bounces at mailman.qth.net
> [mailto:theforge-bounces at mailman.qth.net] On Behalf Of robert hensarling
> Sent: Monday, February 13, 2006 8:38 PM
> To: theforge
> Subject: [TheForge] slitting and drifting help needed
>
> Guys, is there a reference, or chart maybe, of what size slitting chisel
> to use for a given drifted hole diameter?  In other words, if I want a
> drifted finished hole size to be 1/2", what size of slitting chisel
> would I use, not only for this size, but 3/16th's, 1/4, 3/8th's etc. I'm
> referring to the "canoe" shaped slitting chisel.
> I understand that a slit and drifted hole will increase the overall
> length of a given piece of steel, and a punched and drifted hole will in
> fact be a little less.  Do I have this correct, or am I backwards?
> Thanks for the info!
> Robert Hensarling
> Uvalde, Texas