Fred the Red Shirt wrote in
oups.com:

On Aug 12, 11:09 am, Fortunat1 wrote:
...
I'll just have to get a good
quality reamer and prepare each hole carefully. I'll see if I can get
a
drill bit that brings he holes a little closer to the final size.

May I suggest you get more than one drill bit, for the same
reason you need more than one reamer?

.What is the annealing temperature for 4130? You can drill through
a bandsaw blade by spot annealing it, that is you chuck a blunt rod
like a nail with the point ground off into a drill press bring that to
bear
on the spot to be drilled until it gets good and hot, then let it
cool
slowly. Now the spot is annealed and a hole can be drilled with
an ordinary bit.

So I wonder if re-drilling the holes will heat them to the annealing
temperature? Or would it be feasible to spin a rod in the holes
to heat them by friction to soften them? Or would that just
work-harden the surface....

Don't know the answer to any of these questions, but since any sort of
heat treating, whether it be normalising or tempering, is well beyond
what I'm able to do in the shop just by eyeballing the color of the
steel.

One thing I don't underdstand is that I work hardened a small part by
getting a little over enthusiastic with a drill bit. I tried heating the
same part up to red hot and then let it cool slowly thinking it would
bring it back to the normalised state, but it seemed just as hard to
drill as it was before I cherried it.