Joseph Gwinn wrote:
Another poster reported success in drilling the unthreaded holes in a
cheap 1-2-3 block out to allow a 3/8 inch stud to pass through, so I
decided to try it.

Clamped the victim block to the drill press table and drilled it with a
Rodman (made in Germany) 3/8 carbide-tipped bit, using low speed (500
rpm) and lots of water-based coolant.

It squealed a lot, but drilled quite well, leaving a pretty clean hole,
yielding lots of little chips and no long curly chips. The problem came
when I got half-way through, drilling into the cross-hole. The
interrupted cut broke the carbide wings off the drill bit piece by
piece. Things got a lot noisier, but I was still able to complete the
hole, and a 3/8 stud now passes through.

I was able to drill a second good hole with that bit, but that's
probably it. Though I bet it would still drill, but might not make the
full diameter needed.

So, I tried some cheap Vermin America masonry bits. Couldn't get
through one hole, never mind two holes. It took two VA bits to make a
usable hole, and totally mangled both VA bits.

It seems that Rodman uses far better materials than VA. What a surprise.

Joe Gwinn


Methinks that EDM may be the "way to bet" on that one.

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"Truth exists; only falsehood has to be invented."