Re: ATM Re: [atm_free] Stubborn 1/2 " edge zone

["Jeff Anderson-Lee" <jandersonlee@sbcglobal.net>]

Bob May wrote:
> I tend to go in either of two different paths when dealing with TDE.
> First is the TOT method where the lap is stroked over the edge of the
mirror
> with the center of the lap being in the 50-70% zone of the mirror.  Insure
> that you put the pressure on the center of the lap rather than on the side
> hanging over and the edge will soon be in compliance with the rest of the
> mirror's surface.  I'll note that this method also opend the ROC of the
> mirror.
> The second way is to do a stroke where the mirror starts at the 1/3 point
of
> the mirror to the lap and ends when the centers are on top of each other.
> All of the weight is on the part of the mirror that is off the lap, making
> the lap work on the zone from the 50% area to the edge of the mirror.  The
> hands need to be one in front of the other with the rear hand providing
the
> pressure while the front hand provides directional stability.
> This stroke also opens the ROC so that the edge itself becomes part of the
> general curve.  This stroke does have a slight problem sometimes in that
> there will be a hill built in the center of the mirror but longer strokes
> can take care of this as well as chordal strokes of the center of the
mirror
> over the edge of the lap removing the central hill.

Would either of these strokes work on a strongly "bifocal" mirror?  I have
two zones  that differ in focal length by an inch or so with a boundary at
about the 50% radius.  The ronchi test shows pretty much straight lines for
each zone.  I've been doing TOT 1/3 COC trying to blend the zones and I find
that oddly enough the inner zone is (slowly) expanding, even though I'm
working TOT.

Jeff Anderson-Lee
Sacaramento, CA