Re: [ATM] Figuring Methods

["Jerry" <wa4guu@verizon.net>]

And that was the secondary that was a hyperbola that you were working the
center to fix wasn't it.

Jerry

-----Original Message-----
From: Kevin MIchael Zabbo [mailto:chaosopher23@yahoo.com] 
Sent: Sunday, April 30, 2006 3:11 PM
To: Jerry; 'Mike Lockwood'; atm@atmlist.net
Subject: Re: [ATM] Figuring Methods

I'm going to dig a hole in the center of my 13.25"
mirror that's going to be about 2.125" in diameter and
about 1.25" deep.  Do you suppose that will affect the
image at all, or should I mask it with something,
perhaps secondary obstruction? <weg>

Kevin of Eastern Iowa
Seeker of the Darkness

--- Jerry <wa4guu@verizon.net> wrote:

> 
> 
> I said I would say something about how to make a
> smooth center. 
> 
> 
> When you are bending the curve into shape, there are
> two places on the curve
> that in figuring do not seem to behave exactly like
> the largest part of the
> curve.  The two places are the edge and the center. 
> 
> If you followed my description of how using TOT with
> accented pressure on a
> zone would decrease the correction from the zone
> inward from the worked zone
> and increase it to the zone outside the worked zone,
> You can see why the
> edge and the center are different than intermediate
> zones. 
> 
> There is no zone outside the edge and there is no
> zone inside the very
> center. In a sense you can visualize the center as
> having itself as the zone
> just inside it. I gets twice the wear when the edge
> of the lap traverses
> near there. The strokes very near the center wear
> both sides of the center
> and cause it to overcorrect. 
> 
> I will leave the edge alone. This is about the
> center.
> 
> This is top secret so don't let it out.  
> 
> Common defects in the center are bumps, holes and
> holes that are more
> accurately described as dimples. And then there are
> sometimes gouges caused
> by rather extreme pressure of MOT work with extreme
> overhang to the side, or
> maybe some over aggressive TOT work in the center.
> 
> The center is the center of almost all work on the
> mirror. There is a
> confluence in the center of strokes at every work
> position around the
> mirror. And the pressure is highest there. Some
> times it is not gouged but
> just the convergence of one side of every W all the
> way around the mirror
> makes a small but deep dimple.
> 
> If you are going to have a really nice center a way
> needs to be found to
> treat it the same as the intermediate zones. They
> are sometimes uncovered by
> the lap and the center usually isn't.  No one has
> trouble figuring the
> intermediate zones.
> 
> Slicing and Planing:
> 
> Think of the lap's edge motion on a tangent to the
> edge with pressure as a
> slicer. 
> 
> Think of the motion of the lap's edge with pressure
> on a line to and from
> the center of the lap as a planer.
> 
> We want the planing in the center to smooth those
> defects. Otherwise as we
> work to fix the center it will be hard not to slice
> some more defects into
> existence.
> 
> A solution to the converging of all the overhanging
> strokes with pressure on
> the edge of the lap, whether MOT or TOT is to never
> take the edge of the lap
> near the center of the mirror with a direction of
> motion that is tangent to
> the laps edge. That is what slices and gouges. If
> the direction of the lap
> edge when it is near the mirror's center is more on
> a radial line from the
> center of the lap, the gouging does not occur. It is
> more of a planing
> action. 
> 
> This is easily done TOT. It can be done MOT, but I
> think most will agree TOT
> will be easier to control in the center. Very little
> work will do much to
> the center. It is such a small area.
> 
> So TOT accented pressure.  You can stroke more than
> 1/2 diameter because you
> have pressure on the edge of the lap. It is not
> going to rock off the edge
> of the mirror because you are pressing on the lap
> edge over the center of
> the mirror. If you want you can also lift some of
> the weight off of the
> overhang side of the lap, just enough to reduce
> pressure on the edge of the
> mirror. You don't want to actually lift it off the
> glass.
> 
> The closer the edge of the lap is to the center of
> the mirror the more you
> want the lap motion directly toward or away from the
> mirrors center. For
> example in the MOT Big wide W parabolizing stroke
> you would want the strokes
> at the far sides of the W to be more to the left and
> right than forward and
> back.
> 
> TOT accented pressure working near the center, you
> can on some occasions
> draw the edge of the lap past the center of the
> mirror and plow the front of
> the lap, relative to the laps motion, back through
> the center. This can be
> used to plane those dimples and gouges if you have
> them and prevent them if
> you don't have them.
> 
> If you have a bump this how you get rid of it
> without making a dimple, gouge
> or hole.
> 
> Just keep in mind that when you do this there is
> very little glass to be
> removed in that small central area. Just a little of
> this will do a lot. A
> few strokes now and then will do it.
> 
> If you are using the Big wide W parabolizing stroke
> you can go to the side
> the edge of the lap gets to about the 25% or 30%
> zone on most steps around
> the mirror. If you were to work roughly 12 positions
> around the mirror, at
> about 3 evenly spaced places in the trip around you
> go all the way past
> center and then back through center as I described
> above, and on outward
> backtracking the W. I stress again... the motion
> through the center of the
> mirror should not be tangent to the laps edge, it
> should be close to a right
> angle to the tangent. You would not do this on every
> session. You would do
> it as you need to and you will develop a sense of
> how much it may be added
> as a standard practice to prevent ugly things from
> happening in the center.
> 
> This can make a perfect center.
> 
> That is the last secret I will tell you .....
> 
> This is off the list so don't let any of them know
> this.
> 
> 
> Uh oh! I sound like Richard...
> 
> Jerry
> 
> _______________________________________________
> ATM mailing list http://www.atmlist.net/
> 


I published my first novel!  You can get it here, from the publisher!  
http://www.publishamerica.com/greetingcardpro/pickup.asp?CardSentID=126045&r
ID=48283



Their search stringbox is on the right side about halfway down.

search using my name:  kevin michael zabbo
and it will take you right to my book page.

The title is anna's blood, which also takes you there.

Please order your copy soon!  I love you!

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com 

_______________________________________________
ATM mailing list http://www.atmlist.net/