Re: [ATM] Turned Down Edge

["Jonathan Bishop" <jonathan_bishop@sbcglobal.net>]

Hi,

What worked for me was a full sized lap, short center over center strokes
(COC), with MOT. Make sure your lap is not soft, and trimmed back slightly
from the edge. You may need to do this for up to two hours if the turned
down edge is severe. If that does not work probably your lap is too soft.

These short strokes will take care of your turned down edge, and also
produce a hill in the center. Never mind about the hill, as that will
quickly disappear when you return to a sphere.

So the strategy to follow is...

1) Get rid of the turned down edge using short COC MOT
2) Get back to sphere using wide W stroke MOT. This will go very fast so do
it in short 5-15 sessions with testing in between.
3) Then parabolize using variations on W stroke, or whatever method you
prefer.

You can experiment with sub diameter lap. This is usually done with TOT. If
you stay away from the edge you will never produce a turned down edge this
way. Be careful to use the sub diameter lap very gently and make sure it is
in full contact. The lap can be softer than normal to help assure full
contact.

When I use a subdiameter lap I use short circular strokes. That seems to
give me a very smooth polish.

Most people recommend smoothing the figure with a full diameter lap at the
end. I have not found this necessary, yet!

Jon Bishop

----- Original Message -----
From: "Adeildo Sombra" <adeildo@roen.inpe.br>
To: "atml" <atm@atmlist.net>
Sent: Monday, July 12, 2004 7:32 AM
Subject: [ATM] Turned Down Edge


Hello,

While testing my 8 in. f/6, I figured out that it has a turned down edge.
I'm using an almost same size lap.
I think a small lap tool would work better against a TDE. Is that true?
How would be the stroke path if I used a 75% sized tool to eliminate the
TDE?

Thanks.
Adeildo.


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