What's that Lassie? You say that PrecisionmachinisT fell down the old
rec.crafts.metalworking mine and will die if we don't mount a rescue
by Wed, 4 Aug 2010 09:57:28 -0700:

Holes fill with chips and are a pain in the ass to clean out etc, so suggest
dont put any more holes in than is absolutely needed--instead, decide on a
basic pattern for the sub plate and then modify /fab your FIXTURES to match

Damn right. Especially steel chips.
Where I work, they use a grid of 1/2-13 holes in AL plate. Milled
flat in place, and drilled and tapped for helicoils.
The I have to make brass plugs that are slightly tapped to plug them
off flush with the plate. As needed they will add the helicoil
inserts.

Then I have to make up a bunch of plugs for 1/2-13 that will cover the
one turn of helicoil thread while going into the 1/2-13 thread.

When the plate gets worn or dinged, they fly cut .010-.020 off the top
(plugs and all) to true it up again.
--

Dan H.
northshore MA.