Re: ATM 500 grit done, what next ??

[kevin@aquilagroup.com (Kevin Ferguson)]

At 04:25 PM 9/18/96 +0000, Arni Ingimundarson wrote:

>I started grinding my mirror again after a little break.
                                    ^^^^^^^^^^^^^^^^^^^      
>Should I use it with the pitch lap or directly on the tile tool?.
                                                       ^^^^^^^^^^
CAUTION!

Before proceeding, do at least one wet, and check contact with 500 grit again. 
There is a chance that a tile tool will have warped during the break. Draw a
grid with perminant felt tip marker, and make sure the ink is wearing away
evenly.

It doesn't take much warpage to lead to scratching when using 12 or 15µ AlOx.
Maybe do 3-4 wets of 500, just in case. Make that first #500 wet on the
heavy side (maybe twice the recommended ammount for your mirror size) and
spread it prior to contacting the mirror.  This will help cushion a possible
poor fit.

Down to 12µ or so, I think everyone uses tool.  5µ carries some risk of
scratching, so folks with a machine will skip it and go to polishing with
CeO, straight from, say 13µ.  This adds a lot of time to polishing, however,
so if working by hand, better to use the 5µ before pouring your lap.

With the micron grits, it is really easy to scratch or sieze the mirror. Do
not "push" the wets too far...they may last 10-12 minutes or so anyway on a
tile tool... but as soon as the feel/sound  starts to change, (after first
couple minute "break in" that is) time for a new wet.

Every wet of micron grits carries a little risk of scratching....8 wets is
plenty enough, if you did previous grits well...don't due extra wets "just
for measure"...it was one of those that scratched my first mirror.

There has been some discussion of using 12 or 5µ on lap, prior to CeO,
especially if using plastic pads. I don't think this saves much time, if
any, over microchanneling the lap, and starting with CeO.

When you get to polishing, try to polish for first two hours before cleaning
and drying your mirror...it will be worth the wait!

G'luck, and keep us posted on your progress.... As you can see, others may
see importance in what seems a trivial detail.

-Kevin