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Subject: Re: How does one friction weld on lathe?
From: Robert Bastow <>
Date: Sun, 18 Oct 1998 06:13:52 GMT

Bill Machrone wrote:
> When I was a youngster I watched my dad friction weld a drill onto an

> I tried to do the same thing today, needing to put a metric thread on a
> piece of 1/4" CRS rod. I faced the top of a small bolt and a rod,
> chucked them up and ran them together. 
> They got a little warm and they graunched a few times, then the bar
> deflected a bit. When I stopped the lathe, the bolt had little
> stalactites of steel that it had torn out of the end of the rod, but no
> overall welding, just these little spots.
> I straightened the bar, cleaned up the ends, and tried it again. Same
> result.
> Is there a technique to this, or should I stop trying to destroy my
> lathe?
> - Bill

A friction welding machine runs the two parts together under pressure fore a
preset time, until they reach FORGE welding heat. It then stops DEAD an rams the
two parts together under enormous pressure, and a carefully controlled distance.

I have had tens of thousands of parts friction welded to make blanks for after
market photocopier rollers.  These were made from aluminum, stainless, or MS and
comprised a drawn tubular body and two solid end
pieces.  Both welds were made simultaneously on specialized equipment by my

In every case the rule was that the cross section of the ends must be similar.
In the case of tube to solid end piece, I had to prepare the
end pieces by drilling them, bore dia of the tube for about 1/4 x bore dia.,
and, if necessary, turning down the o/d for the same distance.

After a little experimenting, we were successful in getting SS ends welded to
aluminum bodies.

As to whether you should do it on your lathe...It is a useful technique to use
in an on the (usually) beat up lunker in the millwrights shop. 
But I wouldn't like to do it on my own lathe.

Robert Bastow

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