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

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."

"Jeff Wisnia" wrote in message
...


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


EDM? You must have deep pockets. I've drilled through taps and reamers with
carbide endmills.

Having a geared power feed is really nice but possibly not necessary.

OP should consider GRT-series carbide tipped masonry drills from Relton
(www.relton.com for resellers). Drill's packaging specifically states the
drill can go through hardened metal. Special tip geometry and carbide grade.
Typically 1/3 extra $$$ for GRT as opposed to standard masonry bit.

Regards,

Robin

Robin S. wrote:

"Jeff Wisnia" wrote in message
...


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



EDM? You must have deep pockets. I've drilled through taps and reamers with
carbide endmills.

I wuz thinking that's be a good excuse to build your own EDM setup, huh?

Jeff (Just dreaming....)

Having a geared power feed is really nice but possibly not necessary.

OP should consider GRT-series carbide tipped masonry drills from Relton
(www.relton.com for resellers). Drill's packaging specifically states the
drill can go through hardened metal. Special tip geometry and carbide grade.
Typically 1/3 extra $$$ for GRT as opposed to standard masonry bit.

Regards,

Robin




--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

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