Hello Jon,

Somebody posted this URL here a while ago:

http://www.locknstitch.com/

It seems to me that what you are experiencing agrees pretty well with their
explanation as to the mechanisms involved, though I'm only going on
recollection. It may be that either their products or their data could help.

BTW your EDM power supply worked exactly as I hoped on eroding a square
socket into the hardened stud we were discussing a while back. So, thanks
once again on that.

Regards,

Adam Smith
Midland, ON

"Jon Elson" wrote in message
ervers.com...
Nick Müller wrote:
Jon Elson wrote:


Without a heat treat oven, is every weld repair going to end up producing
another crack?


Did you drill the end of the crack? You should do this!
carefuly check that you drilled out the end of the crack (oil and chalk)
or it will certainly crack again.
Preheating by any means will reduce inner tension.
The new crack is 3 inches away, and parallel to the old crack. It is at
the end of the gusset patch, where stess may have been concentrated both
by the application of the patch and by the patched area now being stiffer
than the rest of the platen.

So, this has nothing to do with the end of the crack propagating farther.

Thanks,

Jon