Posts Made By: Preston Engebretson

Good Evening Micheal...I use to have the same ideals...

But learned that asking questions of others, more importantly those that are in the field in the know, will likely reduce by a very great amount of time my investigations...and ...$$$$$

They in general like to answer well founded questions...and reading the latest in telescope technology cannot hurt...

Granted the book is looking at 1 meter plus size scopes, and also looking the the 8.2 meter to 10 meter designs.

But this does relate to out hobby...

JMHO

Best Regards Preston

Micheal Great test on the physical movement...our mirror lateral movement is limited to .0005", but we are working with cored mirrors and astatic axial support

But again, with optics in place your lateral supports are very likely to cause a deformation in the mirrors figure that will be seen when lowered past vertical by placing a load on the front edge of the mirror...I'll leave at that...

Good Viewing and Best Regards for some fine construction details...

Preston

Micheal,
Having been out of Astronomy since my teens, and able now in my 40ties...with funds, and European Clients...4-8meter we have been consulting...

ps...I have had my juices over flowing from some of your post...

Personally, we are working on a 10" and 20" RC robotic observatorys...Then looking to go to perhaps 48"...time will tell...

What is WSP???Out of the loop likely....Our current Research is directed toward amateur...and not commercial...

Very Best Regards, Please keep in Touch...

Preston

Eric, I got a quote on that for a client. As is $35,000 or finished 1/4 wave or better and coated, with delivery to Texas $95,000......and they will happily make another...

How bout BIG Binoculars???

Preston

Hello Gerald, Go to Mark Keitel's post of about 3 Feb regarding his 3rd floor observatory...very nicely done...it may go back further...

Regards Preston

Bill,

I bought the 127mm x 1200mm optic set in a cell from Apogee.
It comes in a plastic non-adjustable cell. The images are good enough for a guide scope which is what we bought it for but it shows the false colors inherant in optics at this price range.

Hope that helps,

Preston

Kwang, The tool in this setup is generally set to a stationary position based on the focal length desired. Moving the tool further out increases the focal length and moving it in decreases the lenght.

Once you are close to the desired focal lenght, you do not move the tool in or out as you will start to develope another sphere either outside or inside the previous one.

In polishing to a sphere, you also keep the lap in the same position as the grinding lap.

One may introduce a bit of ecentric motion to avoid zoning once polishing...

It is only when you began to figure that the arm strokes across the mirror, but at this point the mirror rotation is SLOWED to almost a crawl...like 3-6rpm versas 40-60 during grinding and polishing...

The following is a good site that supports the MOM "Mirror Matic"

http://groups.yahoo.com/group/Mirror-O-Matic/

Very useful and active site...

Hope this helped,

Regards Preston

ps...There are other ways to use the machine, but what I discribed is likely the most popular...and Carl Zambuto also uses this basic method.

GY, you might try the following link...but for a truss tube DOB, I don't see the advantage...other than a little weight savings.

The main advantage for carbonfiber composites in scopes is the near zero thermal expansion so one's focus stays put during temp changes. Stiffness is also greatly increased.

Also, one should protect them from UV rays as they are easily damaged...ie paint your pretty carbon rods...

Here's a link:http://www.graphitestore.com/items_list.asp?action=prod&prd_id=99&cat_id=25

Hope this has helped,

Preston

ps...carbon is not ever resonably priced unless you are looking at a lot of units...price drops from about $25 per yard to $11 but only after some 20+ rolls at 100 yards per roll.

You could likely make them for the price of about 2 rods. If your interested, I could walk you through the process the we use to form tubing from .75" and up.

Mike...check your email...also, I've used the product that Don
mentioned...it works quite well.

Regards Preston

You could likely set it up in a 4 jaw chuck in a lathe. Otherwise if you were to built a wooden jig to hold the bracket and make a circle guide for a router, by taking small steps down of about .050" per pass ...you could remover the material in about 15-30 minutes...

Regards,

Preston