ATM: I had good luck making corrector cell out'a Delrin

[Ed Taychert <elt@irony.com>]

I had good luck making a corrector lens cell for my Mak-Newt on
my shaper. First I made this jig -
http://www.irony.com/Ed/astro/6inMN/CellJig.jpg

A center point for the router bit and five radius points (taking into
account inside edge and outside edge cutting) were laid out. I
inserted bronze bushing in the holes because I plan to make a few
more cells. Sitting on top of the jig is a bushing and collar that
slips over the router bit; that makes positioning the jig on the table
a little bit easier...

... the back right shows a Delrin blank ready to go and the back
left shows center that was cut out from a previous blank ...

I made my first corrector cell out of mahogany because it's so easy
to work with but I didn't like how fragile it seemed when I was
done ... here's a picture of a finished cell with corrector mounted -
http://www.irony.com/Ed/astro/6inMN/CorrectorCell.jpg

More notes on the project:

This picture shows the mirror cell -
http://www.irony.com/Ed/astro/6inMN/MirrorCell.jpg

I stole the back off of a UO mirror cell but now I'm thinking that I
can make that back part out of the "center" left over from the
corrector cell!

At any rate, I did not make the optics, they are from an MN61 set I
bought off'a Markus Ludes. The primary is cored with a one inch
hole. I supported it with a baby version of the center post I made
for my 20-incher -
http://www.irony.com/Ed/astro/20inch/Cell.jpg

Basically, it's a 3/8 inch bolt with a 1 inch bushing; a little electrical
tape is used at the mirror/metal interface. The head of the bolt is at
the back of the cell, then the core support, then an inch and a
quarter neoprene washer, a fender washer and a nut ... the front
nut is just tightened enough to keep the core together ...

The tube behind the mirror cells is a piece of 7" irrigation pipe
from Hastings -
http://www.hipco-ne.com/scope.htm

I uncurled some flocking paper inside the tube, aligned the optics
with a holographic collimator and, using the scope hand held,
took a low power look at moon and Saturn ...

At first glance, the flocking paper looks adequate for the job ... I
usually add one baffle ala Nils Olof''s notes  -
http://astro.umsystem.edu/atm/ARCHIVES/APR00/msg00355.html

just to be sure, but this tube is so small that I'd need a zillion
baffles ... I don't think its worth the work.

I haven't decided how to finish the tube yet, but I'm leaning
toward fabric coating it similar to how I covered my 8-incher -
http://www.irony.com/Ed/astro/8inch.jpg

 - Ed.