Quote:
Originally Posted by mldee
Marc, am I correct in assuming that the cork and rubber mirror attachment ring is now assisted by the bonding material you used to hold the mirror to the new plates, so that there is no flop? Sounds very interesting.
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No - there is no more rubber compound, wood or cork. The mirror and the stainless steel ring are now one unit bonded with a compound which is as hard as steel. The mirror does not touch the baffle tube anymore. It's suspended by three M10 bolts with enough OD in the glass to tilt. There is a 5mm gap between the baffle and the glass, plenty to move.
The mirror flop occurs because the glass mirror was originally held by 3 spacers made out of wood (yes wood
) positioned at 120 degrees, embedded in a lot of rubber filling between the glass and the baffle and cork shims at the back and front. I think this works ok for smaller scope (C8/9) but with mirror weights increasing in C11 and C14 the system has its limitations IMHO. I am now convinced this is the cause of mirror flop.
Quote:
Originally Posted by mldee
The reason I ask is that my "remote focussing" concept, using a rear-mounted Crayford moving an internal tube attached to the mirror assembly, might not then be needed if I just emulated your attachment bonding. Seems simpler.
My approach also probably removes the ability for the scope to operate in normal mode, as the focus tube would be internal to the baffle tube, partially blocking it. I'll use my RC8 for longer FL stuff, so no concern to me.
Finally, do you think it would be a relatively simple engineering task to machine three 120deg radial lengthwise slots about 5mm wide by (say) 50mm long in the baffle tube for (say) 4mm diam focus attachment points to connect to the inner (Crayford-attached) mirror-push-pull tube? Since the baffle tube basically provides all the mirror support and movement dimensional accuracy, damaging it would be a no-no. How does it attach to the rear OTA plate, I can't see from the outside?
Sorry for the endless questions. What I'm trying to ascertain while it's still fresh in your head is whether I should proceed with my concept or just bond up the mirror for rigidity and concentrate on motorising the existing FT focuser.
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I'm not sure what you mean. You can't access the mirror tube from the back of the casting. Can you post a quick drawing? I assume you're using it with Hyperstar exclusively?