Thread: 10" F4 build
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Old 07-03-2012, 09:57 AM
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ZeroID (Brent)
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Join Date: May 2010
Location: Auckland, NZ
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Hi Alistair, bit late to the discussion but Velcro works great IMHO. I used 3 strips 77mm(3") long, 25mm (1") wide Industrial Grade onto 3 x 25mm alum flats that were my 6 point support built very similarly to the diagram previously posted.
The Velcro will support about 500 gms (1 lb) per square inch of surface area suspended upside down.
I use three edge supports, 1 mm gap with a dob of silicon through to the side of the mirror to ensure it doesn't move laterally but they are not really necessary.
As far as I can tell there is zero stress on the mirror due to the spread surface area and characteristics of velcro and it has certainly held collimation without any adjustment required since build.

I'll post a pic from home later if you want.

6 point was best support design, the 9 and 18 looked apparently worse and involved heaps more work. 6 point as you have drawn is easy and works well.

The Serrurier truss is a bit of a fiddle to build, accuracy in build is the key issue but I'm very happy with its stabilty, strength and lightnes. Not to mention it's easy to access parts for modifying as I did last night.
I wouldn't bother with an octagon centre cage. Too hard to build without welding gear etc and at F4 you build will be plenty strong and stable enough. Rolf makes a good case for the design parameters. I also mounted mine to a long dovetail bar. Allows me to slide it in the mount head to balance any changes in accessories and eliminates the need to add weight.

Ignore my 'Rotating UTA' system. Works well enough for visual but when I go serious AP I'll lock it down. It is handy to be able to pop the whole UTA off though to work on although not needed much now, maybe later I might get mod happy.

Last edited by ZeroID; 07-03-2012 at 10:18 AM. Reason: More info...
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