I been following this post with interest. In my business (saw blade
manufacturing and repair) this is a very common solution to stop cracks from
getting bigger and saving a very expensive saw blade. Of course the
direction of the crack has a great deal with whether or not it can be fixed.
The crack should be straight and not curve back toward the edge. The drilled
hole does not need to be very big, just bigger than the crack. I should note
that cracks that have a significant opening cannot generally be repaired
with this method. Further, cracks with significant length pose an altogether
different problem. It is generally reserved for hairline cracks under 2-3"
in length. If you plan on sealing the drilled hole, countersinking both
sides of the hole will aid in keeping whatever plug type you use in. A good
plug to use would be copper plugs similar to that in a saw blade. Insert and
hammer both sides lightly to flatten out and fill the countersink. It takes
the form of an hourglass and will not come out very easily.
Alex Manzo
----- Original Message -----
From: "Randall" <tr3driver@ca.rr.com>
To: <Triumphs@Autox.team.net>
Sent: Sunday, January 14, 2007 02:51 PM
Subject: RE: [TR] crack propagation
> > I'm not sure if this is universally true, but I think so.
>
> FWIW, I think so too.
>
> > I believe if you
> > drill a small hole at the tip of the crack in the casting, you will stop
the
> > crack from growing.
>
> Works with most if not all materials, including aluminum, glass and steel.
The
> trick is to get the hole located beyond the tip of the existing crack,
which
> sometimes cannot be seen.
>
> > You could then fill the hole with epoxy to seal it up.
> > The epoxy, being flexible would not concentrate energy the way the crack
tip
> > does.
>
> Doesn't really matter if it's flexible or not. Even welding the hole up
with
> the same base metal will not cause a weak spot like the crack did.
>
> Randall
=== This list supported in part by The Vintage Triumph Register
=== http://www.vtr.org
|