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Old 23-12-2011, 08:06 PM
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multiweb (Marc)
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Quote:
Originally Posted by mldee View Post
My question is: It does not seem like there is any need for great surface precision in either of the two plates, basically the collimation screws provide the final precision.
That is correct.

Quote:
Originally Posted by mldee View Post
That being the case, if I purchase a couple of pieces of thick (5mm or more) aluminium stock from the local supplier, and have them reamed/drilled/milled etc to fit, taking into account how they work as a sandwich with the existing focuser plate, do you see any need for high precision in that work? Also, it's only an 8" mirror so thread loadings should be less, allowing all aluminium stock.
Everything out of alu will me more than adequate for a C8. It's a small piece of glass. The front ring is pretty simple, the back ring will need steps to be machined so you can mate it to the back of the existing focusing arm. I suspect 5mm is fine. I araldited mine to the existing piece and used a dremel to finish the holes.

Quote:
Originally Posted by mldee View Post
Second question, do you think I can keep the plate thicknesses such that I can use normal dovetail-size hex bolts for the collimation function, of which I have many surplus?
The plate thickness will depend on how much room you have when the mirror bottoms out. You still want to be able to focus at infinity or you'll have to move the corrector further out.
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