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Re: [ATM] The best time to Foucault?
No, Thank You! Roman!,
its so-good to hear from a fellow atm, deeply involved
with a optical, or a mount project!, we here at the list love-it!.
Welcome Back!, and Please keep us up-to-date!, we would
Love to hear how your doing!
PS; your now not considered a beginner,,because ounce you get
that grit under your finger-nails!, we know you've been bitten by the bug,
and you are part of our "ATM-Frat" in good standing!", You are now among the
"Brotherhood!"
[but of course anyone is welcome here, whether you
have made a telescope or not!].
I too, owned several commercial-scopes, before I started "pushing-glass", and
I was glad i did, because I was able to take my time, and create the best
Optics I could, and boy!, was the time spent worth-it!!,, man, I was ecstatic!,
the views were Breathtaking!
Here is my recommendation at this point to be used at your discretion,,,
[form what you've said about your current state with the optic, my current tip
would be to, go ahead and do a 60/40 attack of MOT/TOT. if you have
30-35 sec.-pitch temper.(semi-hard). If you usually use a pitch-temper
of 20-30sec.(semi-soft), try not to use more that slight "hand Pressure"
and a work-cycle of about 20/20min.(20minutes/polish)&(20minutes/cold-pressing).
I myself prefer to use semi-hard pitch, for 5-10lbs of pressure to protect the edge.
because Im allot better-off with a slightly TUE.,[easier for me to correct].
Now Remember, that a "parabola" does have an"Apparent-TDE", that's not the same
as a "True-TDE!", The apparent-TDE can be Easily seen as the slight
"Dimness" of the diffraction-ring" on the "left-side of the Doughnut",,,depending
of course on whether your light-source is on the "right or Left"
[any good atm-book will explain the reason]
in other-words a "Well-corrected parabola" will have a ring-of Light that
is Slightly brighter on one side than the other!(depending on which side
the light-source emanates-from!)
NOW,,if you see one-side lit-up, and the other-side is dark!, then you
absolutely have a "degree-of-TDE".
My Best wishes to you and your Optics!
God Bless,,
John Moore
atm since 1974.
________________________________
From: atm-bounces@atmlist.net on behalf of Roman Toledo
Sent: Mon 10/16/2006 12:37 AM
To: atm@atmlist.net
Subject: [ATM] The best time to Foucault?
*****************************************************
John thanks for the encouragement, I'm still in stage one,
working on 2 mirrors. I've learned a lot so far and know there's more
to be learned.
Right now I'm working exclusively on my second mirror since I
bought a Celestron NGPS 9.25 f/10 so I want to get a fast mirror
done. It seems ;) I've changed my mind again and I'm back in love with
a fast mirror to supplement my viewing habits. not that I'm complaining
about the NGPS I love it.
I've only looked once at my second mirror and I'm not worring
about errors at this time since I'm using a full size pitch doing COC.
I've learned that I like to polish with weights on my 3"thick tool TOT,
it allows me to push nice and slowly and make a smother pass, so far
the edge has begun to polish out and is currently about 50% in from the
edge polished to where there is little light defraction on the edge of
the glass.
I've been working a lot of hours and seem tired, so I'm putting 15
minutes here and there, no real hurry. My first mirror (and my own
creation ;) ) sits there 90% polished but since it's a f/7 it's going
to wait till the fast one is done.
I just also ordered a couple of secondaries from JC Mulherin and once
those arrive I'll work on those in the house and try make progress on
those too, I'll come back and ask about those at that time, specially
how to get them tested, but that will have to wait for now.
I was going to take advantage of all the clouds and polish, but I just
don't seem to muster the energy. the TV won tonight.
thanks again from one beginner and as a update to those wondering what
happened to me ;)
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