mhorowit wrote:
What about all the scratches made by clamping it in the vice and using
an abrasive to clean before welding? arn't those sources of 'stress
risers'? - Mike


You don't need to clean back any further than you will be welding.
'Scratches' should be melted away. Use a slightly worn out abrasive pad
(sand paper on foam), or 120 or greater grit paper. It will give you a
mirror finish. A 'scratch' has to be a significant depth into the
parent material to be of consequence.

'Significant' in this case is a weasel word without definite meaning.
The precise depth is different for various materials. Consult 43.13B
for specific details.

--
This is by far the hardest lesson about freedom. It goes against
instinct, and morality, to just sit back and watch people make
mistakes. We want to help them, which means control them and their
decisions, but in doing so we actually hurt them (and ourselves)."