From: "Ulhas Deshpande" 
To: , "ATM" ,
        
Reply-To: "Ulhas Deshpande" 


Kartik
Saw your post on ATM.
I made a polishing lap using an 8 inch circle cut out of kitchen top
polished granite slab about 1/2 inch thick. It has no problems of warping
or flaking etc. No paint required.Also it is quite heavy so no weight etc
required.
BUT I used the  the piece as is i.e no padding in the center. I have faced
a lot of problems ,still continuing to,as the center sinks out of contact
and I have to keep hot pressing again and again. I belive the way out is to
place,stick?, layers of paper of reducing dia till the centre thickness is
approx equal to sagitta. So an artificial stepped surface approximating to
the mirror curve is made. Then pour pitch to make the lap.
Best of Luck
Suggest you post your progress occassionally on  the CIAA site also. Ulhas Deshpande

--- BBBS/NT v4.01 Flag-4