Dob azimuth motion - materials

[Starkler (Geoff)]

I have seen mention of 'glassboard' being used to line the bottom of rocker boxes on premium dobs, and a superior product to ebony star laminate in the quest to get that perfect azimuth motion.

Does anyone know of a source for this material ?

[RAJAH235]

Might be referring to Fiberglass PCB material Geoff. (as in Printed Circuit Board), before the copper cladding is applied? Never seen a ref to it tho. L.
ps. Try 'Oatley Electronics' perhaps.

[lost_in_space]

If it is what I think it's AKA Fibreglass Reinforced Plastic or FRP. Used to mould baths and shower recesses. One side is smooth and the other "bumpy". I can't imagine it being a suitable replacement for Ebony Star laminate though.

[Vermin (Tom)]

I don't think it's a woven product like PCB substrate. It's a rough random fibre fibreglass panel used in places like shower stalls, also known as FRP (glass fibre reinforced plastic).

Look at the surface material of the top right photo on this page: http://www.bmsizone.com/products/FRP.html (ignore the honeycomb reinforced backing - it is available without this in plain sheet form).


EDIT: Bah! I spent too long looking for that link!

[Brian]

FRP works much better than Ebony Star Laminate on lighter weight scopes. I would check your local building materials dealer or lumber yard. Star Master uses FRp on their smaller scopes.

[Starkler (Geoff)]

I didnt think anyone had replied to this thread until just now....

I'll have to ask Julian whats lining the bottom of his obsession dob.
I didnt have much luck finding a local supplier on the web, or at Bunnings for that matter

[Vermin (Tom)]

I've just been reviewing the ServoCAT install video, and the 18" obsession Dob being used had an FRP rocker base.

[Starkler (Geoff)]

A bit of further research tends to suggest that the bumps on typical frp may be too big for smaller scopes, causing a wiggle as the scope is rotated.

Plan B is to order into Bunnings some Wilson arts ebony star (#4552-50)laminate.
Failing that, Formica #1782 Stardust Quarry Finish is also recommended.
Anyone in Melbourne willing to share the cost of a sheet? I anticipate something on the order of $30 to do a typical gso dob base.

edit: Have since seen that quarry finish is now replaced by pearl finish

Geoff, the best mod I have made to my GSO 12" is also a cheap and simple one. Unbolt the two halves of the base, go to Mitre 10 and buy a 305mm lazy suzan bearing for $27.50 and a longer nylon locking bolt for $.75, follow fitting instructions making sure that centre of bearing is centre of base, bolt two halves back together using new bold and 6 old cd's as shims between base halves, these can be adjusted by adding removing to get it just right, then tighten bolt until all free play is removed between two halves, AZ motion will now be as smooth as silk and can be adjusted so it can be moved with as little as your breath or as much as a shove. Do it, you will not regret it, tookl me about two hours to complete. BTW, the bearing will support 80Kg's so you have no worry about weight.

[ving (David)]

thinking of useing a set of lazy-susan bearings... anyonr know if this will work?

[iceman (Mike)]

Hey David, did you read the post directly above yours?

[ving (David)]