From: "DAVID K OESTREICH" 
To: "Jerald F. Wright" 
Cc: ,
        "ATM shore" 
Reply-To: "DAVID K OESTREICH" 


I woulkd heartily concur with your point on the limitations of scope making classes.
Vlad did make a valid point as well as others. Learn what you can and
synthesize and formulate what works best for you. The critical mistake I
made was trying to accomplish all this in the limited amount of time
afforded for this class.
!2.5 " is no small feat for a first project granted. But when you add to
that the task of building your first truss scope and all the engineering
concerns. One month to accomplish this is RIDICULOUS. Experience is the
best teacher.
Knowing what one's limits are is probably the most crucial thing any of us can learn.
I bit off more than I could chew in one month. My fault. I put every ounce
of my spare time into this project. Scope building alone accounted for 80
plus hours closer to 100 plus. The mirror grinding/polishing was probably
close to 30 hours or so. There are guys out there with far worse stories
including a gentleman with a 20" project I heard from.
My principle error was the belief that I needed to finish this because I
needed John's help to do it.
History poves that thinking in error. We all stand on the shoulders of
giants. The giants that came before us and figured most of this out for us.
A lot of the work of those giants is synthesized in book form, on the web
and in this group. The main tool I forgot to bring to the class was my own
brain and critical analytical skills and my own sense of self
confidence.... that little voice in each of us that says D{at}mnit I know that
I can do this! I think I heard this opinion voiced by about a half dozen of
you. I am listening and I hope that others that are or will be in jams
similar to my own can learn from it.
-Karlo
----- Original Message -----
From: "Jerald F. Wright" 
To: "DAVID K OESTREICH" 
Cc: "ATM shore" 
Sent: Friday, December 20, 2002 4:57 PM Subject: Re: ATM HELP! mirror
making crossroads


>
>     Anyone's first mirror is not likely to be their dream telescope.  So I
> wouldn't spend much time crying about what you don't like about number
one.  Do
> spend time making plans to make number two more to your liking.  You
should do
> better on number two.  And take some time out to appreciate that you
finished
> number one.
>
>     I second Vladimir's points.  You make the mirror. You measure the
radius.
> You decide when it is polished. and you decide when the figuring is
finished.
> And you pick from all those various methods for doing those processes
which to
> use.  It is nice to have experienced advise available. But you should
learn each
> process yourself as you proceed, what the desired outcome of each is, and
how to
> know you have reached the desired outcome.
>
>     I don't really know, but I think Michael Burr's take is probably
correct
> about John Dobson having more of a bent toward getting scopes to the
masses so
> to speak. There is really nothing wrong with that.  Like I said in the
> beginning, your first mirror is not likely to be your dream scope. Get
someone
> through that first mirror and if they have TM in their genes they can make
and
> learn more.
>
>     Also I would think that most classes would have time limits that would
not
> allow time to be meticulous. Unless the class instructor has unlimited
time the
> instruction would have to be limited to helping students through each
stage in
> time to move to the next. Not likely all will be truly ready to move to
the next
> step. But if you only have a limited time you move to the next ready or
not.
> Learning the process is more important than each mirror being perfectly
made.
> Most classes teach you methods to make a mirror. After making that mirror
you
> hopefully know enough to learn to do them well enough to make a high
quality
> mirror. I have helped individuals make mirrors. I can't imagine what it is
to
> help  a number of people in a class to do a good job on each step of
making a
> mirror. Some of those mirrors are going to have flaws. They will probably
still
> work and the maker will have a mirror to make a telescope with. It would
have to
> be extremely bad not to bring a smile to the makers face on viewing first
light.
> Class mission accomplished. An ATM is born. This is good.
>
>     I recommend Texareau's "How to Make a Telescope" as the
best book on
mirror
> making.  I wouldn't send someone off to make their first mirror without
it.  It
> is unlikely you will run into a problem that he doesn't cover.  I don't do
> everything the same way as in his book. There are many different
techniques.
> All of his will work.  If you use a different technique and it does what
needs
> to be done that is ok. I suggest reading the book before, during and then
> especially after making you mirror.  If you are like me there will be much
you
> missed in that book that you will see after you know from experience what
> Texareau  is talking about. It will make the important things stick to
your grey
> matter better.
>
>     As for advise on what to do with your mirror tool and lap, I know what
I
> would do.  But I have seen all of my suggestions given already although it
was
> split up between about 4 responses to you.  Well there is one idea I
haven't
> seen mentioned.  Keep the f8. It is your first mirror.  Get another blank
for
> your f6. It will only add to the work by the amount required to hog out to
f8.
> Once you have done that you will be where you are with your
"first mirror"
> regarding grinding it to f6. The expense is for one blank and you still
have the
> number one mirror that you may want to do something with later. You can
refigure
> it if it has a bad figure.  In fact it wouldn't be such a bad idea to see
if you
> can put a good curve on the f8 before doing the f6.  If you can't get a
good
> curve on the f8 you probably won't get a good curve on an f6.  I'll say if
it is
> fully polished from center to the edge the turn down can be polished out.
>
>     I wouldn't want a 12.5" f8 to be my only scope. But If I were able to
> permanently mount it I would like it. An f8 telescope makes the best use
of
> commonly available eyepieces. You can get the lowest reasonable power with
> eyepieces around 50mm. And the commonly available short fl eyepieces will
get
> you to the upper limits of reasonable power. I wouldn't want to carry
around a
> monster though.
>
> Jerry
>
>

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