[TheForge] shrink fit techniques

Fri Feb 1 11:16:00 2002

Mike, One, the dowel is A36. It is inserted cold into a hot hole. The hot
hoe is quenched to shrink it around the cold dowel.  The dowel and hole are
the same size. Two, I tried driving the cold dowel into a same-size cold
hole.  The dowel will freeze after about an 1/8 of an inch and begin to
upset between the  2 pieces to be joined, leaving a gap.
RW
----- Original Message -----
From: <[email protected]>
To: <[email protected]>
Sent: Friday, February 01, 2002 10:52 AM
Subject: Re: [TheForge] shrink fit techniques


> Two things,
> One, you say dowel.  If the dowel is drill rod, you may be getting it hot
> enough that when you quench it you harden it.  That being the case, it
will
> change size (austenite to untempered martensite), carbon steel grades will
> usually shrink, and the S types grow, although it usually grows much more
in
> length than in diameter.
> Two, try cooling the pin and not heating the hole.  The hole may be
getting
> smaller from heating, then when you force the pin in it actually acts like
a
> drift and enlarges the hole.
> Michael
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