Re: ATM 21" f/6 Rough Grinding Lesson Learned

[Dave Smith <smithers@ucla.edu>]

>> > Any comments from the more experienced members out there?
>> >
>> I agree on the more grit idea.  I found that using about
>> 3 tablespoons per wet on my (long idle on the barrel) 18"
>> blank worked much better. I will give the windex a try
>> next time.

>Hi
> I find this strange. My experience is that too much grit
>didn't grind as fast. I found that vary small amounts
>added often cut much quicker. I would suspect that the
>reason for the difference is that you may be grinding
>longer before adding grit. I would add grit about every
>5 strokes and wash about every 40 strokes.
>Dwight
>

I'd have to agree with Dwight.  My 6" mirror was overkill for the
machine...it took very little time or grit to reach sagitta.  But my
experience with the 13" blank and full size tile tool indicates that .004
to .005" can be removed every 10 to 15 minutes.  I found it best if I
sprinkled a small amount of grit (~1/2 teaspoon or about 3 grams) uniformly
across the exposed surface of the tool (MOT) every 3 to 5 strokes while the
machine was running.  I alternated adding grit and spraying a fine mist of
water onto the tool.  Too much water and the cutting action was reduced (No
big surprise...it just washes into the channels between the tiles and then
out onto the turntable!).  "Very moist", but not a slurry.  I know that's
not very scientific, but I hope it helps.

Good luck,
Dave