ATM Secondary for 6"f8 attempt 2

["Keir Davis" <kbd@tpg.com.au>]

First attempt failed when I assumed (erroneously) that I had penetrated all
of the glass.
The cut took around 2 hours....with constant lubrication (turps delivered
manually via a funnel - VERY messy and wasteful.  I now have a syringe glued
into the end of some tubing; much better delivery....) and 120 grit every 30
secs or so.
Believing to be all the way through the glass (I found this difficult to
judge actually) I attempted to prise the topmost plaster-cylinder from the
elliptical but the latter was still attached by a tongue of glass about 1/3"
wide.
:-(
Silly me.....

I purchased another piece of 3/8" plate (the company actually cut and ground
it to 152mmD ) and went about the preparatory grinding of it against its
backing with 320 grit. (As per Thompson's instructions....).

I left the boxed and plastered plate for five days and began cutting this
afternoon.
THIS TIME though the cutting is progressing (frustratingly) slowly.
I haven't changed a thing from before.  Same grit, same lube, same rotation
speed of the drill press.
Not sure for the slow pace.  I even nick the end of the pipe with 'v'
grooves to assist cutting - which helps a lot.
I have begun to penetrate the plate and have perhaps driven the 5 inches of
free pipe a half inch into the plaster/plate AFTER THREE HOURS!!!!
Yawn.......
The only difference between this cut and the last is that the last plaster
sat with the plate for a few years before I was ready to do a cut.
Does plaster age?  Become soft over a few years?

Anyway, tomorrow I will proceed and hopefully by tomorrow afternoon I'll
have the four planned ellipticals cut from the plate.
I then plan to cut a half dozen (???) circular pieces to use as fill for the
blocking up.

Stay tuned....

ps - if anyone has an idea on how to cut faster, you'll become my new best
friend!

:-)

Keir