Re: ATM Stuck Lap

[Anthony Stillman <atmer@flash.net>]

>...poured hot pitch
>...greased proof paper
>...slightly off centre
>...1/4 " has stuck to the glass
>...some adhesion from the paper / pitch surface also
>...pitch ...not...out to the edge

>...what do I do


Duncan,

First, take some deep breaths and calm yourself.  Nothing that has happened
is irreversable.  Nothing that has happened will harm your blank.  The
disks are spererable.

You have several options.  Generally I opt for one of the following three.

1)  Run, dribble, warm water from a faucet onto the interface between the
disks.  After twenty or so minutes, look through the glass and see if the
interface is wetting.  If it is, that is water is seeping between the two
surfaces, keep this up until the disks seperate. You may need to push them
apart (see below) I put rubber at the bottom of the basement sink when
doing this and lean the combo tool side out.  I don't want the glass
sliding off.

2)  Soak the whole mess in faucet hot water.  My basement tap is close to
the water heater so this is really hot.  When I haven't been at home I've
used boiling water and kept adding more.  I do this until the pitch is
gooy.  Then I seperate the tool and glass with my hands.  Thick rubber
gloves help a lot.  This distroys the tool, but  with a quick application
of thick cerium paste you're immediately ready to make a new one.

3)  Stick it in the freezer.  This distroys the tool, its messy and its my
last resort.  I've only used it onece.  The pitch shatters easily with a
bruise to the butt of you hand from the edge of the tool backer.


To slide the blank and polishing tool apart I place the combo mirror down
on a flat surface close to a wall.  I block the mirror back away from the
wall no more than 1/2 inch with a short (less than the mirror thickness)
piece of wood.  Then I push the tool toward the wall.  The trick is
constant steady pressure.  Don't wack at it.  Impacts shatter pitch and
glass.  For large surface areas a leaver works well.

Take your time.  An hour under the faucet and twenty minutes pushing is
little compared to a year of work.

Also, next time use a thick cerium or rouge paste as your separator.

Finally, an 1/8 inch thick layer of pitch is all that is actualy needed to
polish.  A 1/4 inch can be more convenient.  A boiling water hot press will
distribute pitch quickly.  I let the air out with a single pressed in
channel to near center, ala Earl Watts.

Good luck and don't worry, it will be all right.

Anthony