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Re: drilling exhaust manifold

To: Calvin Krug <ckrug@laf.cioe.com>
Subject: Re: drilling exhaust manifold
From: Ross MacPherson <arm@bc.sympatico.ca>
Date: Sun, 4 Jul 1999 09:40:09 -0700 (PDT)
At 05:51 PM 7/2/99 -0600, you wrote:
>I'm hoping one of you mechanical-types can help me out.  I recently had a
>steel exhaust manifold flange welded, and now I'm trying to redrill the
>hole for the stud.  I can't find any drill bits that will cut through the
>welded steel.  I've tried regular high speed drill bits, titanium-coated,
>cobalt, and most of them won't even touch it.  Yes, I'm using cutting oil.
>I've managed to get about 1/8" through, but the more I try, the less effect
>I seem to have.  Any ideas?
>

Calvin,

The weld/air-cool cycle has hardened the steel.  Use a MAPP or Oxy/Acetelyne
torch to heat the area you want to drill to cherry red then quench with
water. Submerge the part in a bucket if possible.  This will remove the
hardening and you should be able to drill easily.  Hope this helps.

Cheers,
Ross   MacPherson
TC-3528 , `66 BGT, NEMGT - #11849
Surrey, BC, Canada


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