I just sent this off to the Yahoo mill-drill group and decided some
rcm folks would probably be interested, too.

Last week's postings about the undersized through-holes in 1-2-3
blocks reminded me that I'd wanted to try something. So I dug out
the 3/8" carbide masonry drill that I'd bought for a quarter at a
garage sale last summer, took a 1-2-3 block, and tried opening up a
hole. Loud, hot and lots of little blue chips. And a 3/8" hole.
Drilling one "web" at a time - meaning four webs to get through on
the 2" dimension - and letting everything cool between times, I got
through six webs before the drill tip broke up. So I've got one
hole opened up to 3/8" through the 2" dimension and another halfway.
Not bad for a quarter. Now to find a few more 3/8" masonry bits.

Tove

through six webs before the drill tip broke up. So I've got one
hole opened up to 3/8" through the 2" dimension and another halfway.
Not bad for a quarter. Now to find a few more 3/8" masonry bits.

There might be stress in the block and I wonder if
the block still be square when you are done.

Chuck Sherwood wrote:

through six webs before the drill tip broke up. So I've got one
hole opened up to 3/8" through the 2" dimension and another halfway.
Not bad for a quarter. Now to find a few more 3/8" masonry bits.

There might be stress in the block and I wonder if
the block still be square when you are done.

I wondered that myself. And decided it was worth experimenting with
a cheap pair of 1-2-3 blocks. When I'm done, I'll check them and if
there's any distortion, I'll have a matched pair of pencil holders.

Tove

There might be stress in the block and I wonder if
the block still be square when you are done.

I wondered that myself. And decided it was worth experimenting with
a cheap pair of 1-2-3 blocks. When I'm done, I'll check them and if
there's any distortion, I'll have a matched pair of pencil holders.

Or you could regrind them. They would be a little under sized but
that usually is not a problem for fixturing.