Help on finding Parts and Services for Dob's.

Hi y'all.
I know some of ye have built scopes and
fine scopes they are too.

I wonder could I get a bit of help from you or indeed
anyone that has bought the following in the past
Cheers.


1. Re-silvering of Dob mirrors
2. Focusers
3. Source for teflon suitable for the rocker box.
4. Telrads
5. Mirror Cells.

1. Re-silvering of Dob mirrors

Ive read that some companies use purer silver and the results are much better. But obviously it is more expenslve then a lesser mixture.

Two companies in the UK I know of will aluminise mirrors - Galvoptics (Imageoptics) in Basildon, Essex and Orion Optics UK. Both are reliable. Orion, however, offer an enhanced / dielectric reflective coating (~98% as opposed to 86% for plain aluminium.)

Silver has significant limitations. Yes it is very reflective (~98%+) but only at specific wavelengths. I think Orion Optics have a comparison chart on their site. In short, don't bother with silver.

Orion may be able to help you with small pieces of Teflon... or you can order large sheets of it from Radionics in Dublin - *expensive!* I may have some off-cuts floating about the workshop - remind me later.

Telrads - the bees knees! Definitely get one instead of an optical finder. *Much* easier to use.

Mirror cells - give me your mirror specs (exact diameter / thickness, material-plate/pyrex/other, exact focal length and size of secondary obstruction) and I'll optimise a design for you. Once you have that you can knock up a cell from plywood very easily.

Phil.

Forgot focusers!

JMI do an excellent range of low-profile 2"/1.25" Crayford focusers. These are the biz.

Phil

Orion..............thats the one that i read do a fantastic job of it.

I dont think you can get a modern silver mirror, in the auld days silver mirrors were the way to go but were very fragile and tarnished quickly, with modern dielectric coatings there is no need for them anymore.

Featherlite and JMI do some excellent focusers for dobs,

You'll find a cheap second hand telrad on astromart, thats where I got mine.

Mirror cells are a little different, they depend on the tube they are mounted in and are often custom built. If you want to build your cell, then look at the following link
www.davidlewistoronto.com/plop/
Plop is a program that designs the cell for you, very handy.