try slowing your speed way down and apply more preasure
gary
----- Original Message -----
From: Jim <microdoc@apk.net>
To: <abadeker@tribune.com>
Cc: <mgs@autox.team.net>
Sent: Thursday, October 21, 1999 10:28 AM
Subject: Re: drill-resistant weld
> Nasty, nasty, nasty.
>
> I hope someone comes to your aid. I had a situation like this occur in our
> prototype machine shop. As the work was being bored for tapping, our
continuos
> oil spray was apparently hardening it. The tap went in maybe 1/2", began
to get
> very tight, finally seized and snapped when we tried to remove it. Had to
junk
> the whole thing and start over.
>
> I have a friend who is a tool and die maker at FoMoCo, a very skilled
welder, a
> great no-plastic body man, and of course an MG nut. He is not on the net,
so if
> you don't get some real help right-quick, send a note to me and I'll ask
him
> for some advise. He doesn't always like to share what he knows, and that
is
> unfortunate because he knows a lot.
>
> If you encounter stripped threads again, be advised thread repair kits are
> pretty inexpensive especially compared to this.
>
> Jim
>
> abadeker@tribune.com wrote:
>
> > Listers:
> > After the crazy itinerant welder stopped by and welded shut the
> > stripped stud holes on my A's front shock mount (not the job I
hired
> > him for, but never mind), I've been trying to drill them out and
retap
> > them. One I succeeded with, starting small and working my way up to
> > 5/16. But the second has me stopped: I got a 1/4-inch cobalt bit
> > through, but can't step up to a 5/16th, surprisingly; it went in
about
> > 1/16 inch and just sits there, spinning and no doubt making the
whole
> > problem worse by heat-treating the already very hard metal. I
bought
> > another 5/16 cobalt bit, thinking I had dulled the other, but no
soap.
> > I don't have a torch (aside from propane) to anneal the area, even
if
> > that would work. I can't get at it from underneath; it's the
inboard
> > hole and is blocked by the rest of the frame. I'm thinking of
slipping
> > a narrow cold chisel down onto the `collar' created by the shallow
> > penetration of the 5/16th bit and giving a tap, in hopes of
creating a
> > ridge or chip for the bit to get hold of.
> > Any better suggestions?
> > Thanks,
> > Andy Badeker
> > '60 coupe
>
>
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