Re: ATM Pitch lap question!

[arning@itn.is (Arni Ingimundarson)]

> I use wooden polishing tools all the time.  I do coat them in epoxy to
> seal the surface.  On the bigger wooden tools, I try to approximate the
> convexity of the tool with adding smaller radii pieces of very thin
> veneer.  This keeps an approximate constant thickness of pitch across
> the tool, which I find very important.

Is 8" small enough to dont have approximate curve???
Should I pour a new lap on a tool with approximate curve ?

> Generally, my first comment when someone says that polishing is leaving
> the mirror gray, is that polishing is not happening.  One should be able
> to get a surface shine in the first few minutes of polishing.  If not,

I got a shine after about 30min when I started polishing.  But my lap
was not in good contact in the center so it didn't polish there, just
on the edges.  But next day when I startet polishing the edges got gray
again.  It looks to me that this is a film of CeO on the mirror that I 
cant clean off!!!!!  It has been this way ever since :(

> then the pitch is in poor contact, or the polishing pressure is
> non-existent, or fine grinding did not go well and left too many big

I have about 5kg weight on the pin!

--------------------------------
Arni Ingimundarson
arning@itn.is
Electronics Technician
Amateur Telescope Maker
Iceland.