Smooth bearings for Dob

[Sir]

Hello!

I have an 8" Dobsonian whose bearings are decidedly unsmooth, and have been looking up suitable ways of improving this. Most sources seem to suggest Teflon + Ebony star, only it seems like ES has gone out of fashion... another suggestion I've heard is fibreglass reinforced plastic (FRP), although I have no idea whereabouts I might find this?

Does anyone have any suggestions for smooth dob bearing materials, and where I might be able to pick some up the small amount required? I live in Brisbane.

Cheers

[AG Hybrid (Adrian)]

What kind of 8" dob are we talking about? Home made or the mass produced - Chinese variety?

[Sir]

I'm afraid we're talking about the latter. Here's a nifty link: http://www.ozscopes.com.au/dobsonian...xon-8inch.html

However, for my particular scope the tube is not attached to the mount in the same way it is in that photo... instead it looks more like this: http://home.primus.ca/~gmuller/equip.html

I took off the tube and could see two small blocks of a white, smooth material on both sides of the mount where the tube sits (altitude bearings?) although I don't know whether that would be teflon-like material or the frp-like material? Three pieces of the same material are attached to the base section as well.

Cheers

[Allan_L (Allan)]

I didd not like the ebony star on my 10 inch dob so I found another post that said they bought a lazy suzanne type assembly from Bunnings for about $28 or so.

I did the same and found that it was so smooth it would turn by itself in the wind.

Soo this is fixed by adding some carpet type runners (for use on bottom of furniture etc.)

I find this works brilliantly. And cheap!

Good luck with it.

[astro_nutt]

I replaced the teflon with some pieces cut from a cheap nylon cutting board you can pick up from those $2 bargain shops. Just remember to sand the cut edges to a fine finish, not shiney!
Cheers!

[gary]

Originally Posted by Sir

Most sources seem to suggest Teflon + Ebony star, only it seems like ES has gone out of fashion...

Try Formica Stardust #1782.
See http://www.formica.com/en/home/dna.aspx?color=1782

Ebony Star was manufactured by Wilsonart Inc.

Dave Kriege found through experimentation that textured laminates surprisingly
provided less friction than smooth laminates. (Tip: read "The Bible" page 72 ).

Both Formica and Wilsonart offer a variety of textured laminates.
In his book, Dave mentions that Wilsonart call their textured surface "Touchstone"
and Formica call theirs "Quarry Finish".

I think he picked on Ebony Star and Stardust because of what he called
the "pleasing coincidence" that their names contained the word star.

Others he recommends in "The Dobsonian Telescope" include -

Wilsonart Inc Touchstone range -
#4406 Diamonhead
#4408 Surfside

Formica Quarry Finish range -
#1816 Fogdust
#1783 Firedust
#680 Granite

But a similar textured laminate from any manufacturer will do.

Though there is a representative for Wilsonart in Australia, Formica would
be the leading brand of the two here in Australia.
See http://formica.com.au/

There is certainly no magical "pixie dust" in Ebony Star that makes it the only choice.

Best Regards

Gary Kopff
Managing Director
Wildcard Innovations Pty. Ltd.
20 Kilmory Place, Mount Kuring-Gai
NSW. 2080. Australia
Phone +61-2-9457-9049
Fax +61-2-9457-9593
sales@wildcard-innovations.com.au
http://www.wildcard-innovations.com.au

[Sir]

Thanks everyone for the responses!

Would anyone recognise which material my dobsonian currently has for bearings, as I described it earlier? Is it likely to be teflon or a ebony star-like textured laminate?

If I already have one of the materials, I suppose I only need to get a hold of the other?

Cheers

[Sir]

Bump.