Quote:
Originally Posted by Kunama
In the absence of the 'real McCoy' I am going to go down a different path altogether and will report my findings once I have had a chance to test it.
I don't think that slander applies here Alex, after all, these are just people expressing opinions based on personal experiences as you are. I would personally think that looking at the texture of the 90, it would probably be fine for the lightweight scopes you build. I would have some concerns about using it in larger scopes. My mirror box with cell and primary is over 40 kg without poles and UTA etc.
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Matt is 100% correct. With the small to medium aperture light weight scopes Alex is building the ebony star 90 pattern will work ok. I used 4552-90 on a 10" scope about 14 years ago and it worked ok. I re did the base to that scope a couple of years later with 4552-50 and it was an improvement. I didn't re do the base just to change the laminate, its motions were ok, I rebuilt it to change other things with the base like internal battery pack etc.
Where 4552-90 fails is with medium to large aperture scopes over 16" built along the traditional obsession type design. Scopes of this design are quite a bit heavier than the ligtweight compact designs of the same aperture. The material fails on the azimuth bearing, it will usually still work ok on the altitude bearing.
That however is all pretty academic as I have suspicions that 4552-90 has also been recently discontinued and is no longer in production. The existing stocks however should last a while. As Dave Brock mentioned the Wilsonart #35 pattern is a heavily textured pattern and it should work well. I believe that overall it will be a better choice than 4552-90. It is also still in current production.
The process Matt is proposing will work well. I know what he is using and I am privy to some previous testing with it and I know it works well. The downside is that it is more difficult to fix to the base of the rocker box. However looking at the quality of Matt's workmanship thus far, I am sure he will be fine.
FWIW most of the professional large aperture scope builders in the US use "glassboard" on the bottom of the rocker box but it is very difficult to source in Australia.
Cheers
John B