[TheForge] shrink fit techniques

[Larry and Pat Brown]

I was having problems with this idea of shrink fitting years ago, sometimes 
it worked sometimes it didn't.
I was talking to Bud Oggier at a Northeast Blacksmith meet and he explained 
that if the outside piece wasn't evenly heated from the outside in, the 
center could get smaller resulting in you being puzzled about why it now 
won't go together. Also if you are heating the outside piece too hot it 
will upset around the center when cooling and actually loosen up when cool 
(The problem I was having). The pieces should be not able to go together 
cool, (off by a thousandth or so, make a test piece to get correct sizes) 
if possible cool the inside piece, heat the outside piece slowly to almost 
red or so, put together quickly and align or hold, let cool in air or quench.
Larry Brown





At 10:14 AM 2/1/2002 -0500, you wrote:
>I'm having varying degrees of success attaching metal parts together by the
>use of drilled holes filled with metal dowels using heat and a quench as the
>"adhesive".  If I heat 1 1/2" solid and insert a cold 1/4 or 3/8" dowel and
>quench, the result is a tight secure joint.  But when I insert this piece
>(cold) into another  "hot hole" and quench, the second joint is not as tight
>as the first joint .  I really like this approach for many applications and
>would like to perfect the "shrink fit technique".  Any knowledge and
>experience with this technique is most welcome and appreciated.
>RW
>
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