From: hermit 
To: Bob May 
CC: atmlist 
Reply-To: hermit 


I THINK the problem with a small lap is keeping the weight in the center of
the lap.  If you could find a weight that is "tall" and find a
way to affix it to the lap, that might help.  I did something like that on
a larger scale.  I think this would be much easier with a machine.

Ken


Bob May wrote:
>
> OOOHHH, I've SEEN that problem!!!  And, BOY, HAVE I EVER! ! !
>
> The guy that is doing a 4.25" mirror at the class has that same basic
> problem anytime that he goes to the full sized lap.  It is amazing that it
> takes about half an hour to go from a near sphere to that surface with the
> full lap!  Even a new lap does that!  How it happens, I'd love to hear of
> it.
>   I had him make up a 3/4" lap on a short stick and local working
has gotten
> the surface to a sphere.  The guy has been at work so long on that surface
> that it most assuredly is quite free of any pits.
> The problem tho with the small lap is that you are going to probably be
> digging little rough rings if you try to be too repetitive with your strokes
> so be sure that you tend to randomize the lengths and positions of the
> stroke on the mirror.
> I've tried regular blocked laps, beeswax laps, flat laps and microfaceted
> laps and they all seem to be able to make the same surface and the only
> difference is the speed at which the surface is made!
> Bob May
> http://nav.to/bobmay
> bobmay{at}nethere.com
> NEW! http://bobmay.astronomy.net

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