Re: [ATM] Not tde or tue, important oblate spheroid, ellipsoid

["lütfü" "çakmak" <lutfu_cakmak@yahoo.com>]

Hi Jerry,

Thanks for your beneficial advice and everything. 
I took courage from those.

Mot big W ?

http://stellafane.org/atm/atm_mirror_ref/atm_strokes.htm#The%20Normal%20Stroke

1- the W normal stroke for parabolizing
2- the W center deepening stroke 

Which one should do ? I took a little bit hesitation.

My ronchi grating is 100 lpi

Best regards,

Lutfu


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

> Ok Lütfü
> 
> That smoothed out rather well. Trimming the lap is
> probably what helped it
> get smoother. That is a hill. The edge looks good.
> 
> The hill shouldn't take long to take down and I
> would say that you may as
> well do some normal MOT big W parabolizing stroke as
> illustrated is most all
> ATM books.
> 
> Are you familiar with that stroke?
> 
> 15 minutes, maybe 20 minutes if you stroke as slow
> as I recommend. Resist
> the temptation to do too much work at once. You will
> probably need more work
> than that but you need to test and see that the
> curve is going the way you
> want it to. If it is not going right you will want
> to know before you go too
> far. You can adjust the stroke by what you see
> happening on the surface.
> 
> The normal MOT parabolizing stroke almost always
> works the center faster
> than the outer zones. If that is the way it works
> this time it might just
> take care of the hill and get you on your way to a
> smooth parabola. 
> 
> I'm still a bit worried about whether the pitch lap
> will last until you are
> finished. The smoothness of your surface now gives
> some hope it will last
> long enough if you do not make any figuring errors
> on the way to the
> parabola. Unfortunately that is almost never the
> case on a first mirror.
> Maybe this time.
> 
> Be sure to trim any pinches in the channels. In
> figuring you do not want the
> lap to start behaving badly because it can mess up a
> good curve and surface
> smoothness.
> 
> Press well, stroke slow. 
> 
> How many lines per inch (or mm) on your grating?
> 
> 
> Jerry
> 
> 
> 
> 



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