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#26 Mr Magoo

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Posted 12 January 2013 - 04:02 PM

Here is the info I used from what I ran.

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#27 Mr Magoo

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Posted 12 January 2013 - 04:08 PM

This is what I drew from that for the layout. Does this look correct?

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#28 Pinbout

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Posted 12 January 2013 - 05:48 PM

Great, it's cool to do it yourself. Stupid iPod won't let do a gremlin.

#29 derangedhermit

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Posted 12 January 2013 - 08:44 PM

Seems like it because the right one has 6 clearly defined spots. I'm assuming that the big red donut hole in the center of the right one is not good.

The center of the mirror is in the shadow of the diagonal, so it doesn't matter.

#30 Mr Magoo

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Posted 13 January 2013 - 12:16 AM

My AutoCad skills are a little rusty. Took me a bit. I'm going to try and do the 9 and 18 also. Can't do the 3D although I do have the full version. Never got that far in school.

#31 Pinbout

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Posted 13 January 2013 - 09:03 AM

I do my 3d work in 3dmax. I use to be able to work 3d in autocad but that was a long time ago. :grin:

#32 Ajohn

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Posted 13 January 2013 - 03:28 PM

Never used one of these types of supports as when I made mirrors the blank thinknesses were ok. A thought has struck me though, Be interested in comments. As I am probably going to be making another in the near future.

Taking ferric stainless as that has a low coifficient of expansion it's 10um/m/C. Aluminium is a bit more than twice this. If the support bars are 50mm long they change at 1/20 of that or 500nm / C so if there is a temperature difference of 1/250 C there is 2nm difference in the support height and it's hard to imagine them all being at the same temperature to that sort of accuracy and plop goes the mirror. I have also heard of people testing mirrors mounted like this and running into problems even when they are lying flat which sort of suggests the problems are more than 2nm. I also feel it would take a pretty thick backing plate to limit deflection to that sort of extent so also just how thick does that have to be?

John
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#33 Don H

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Posted 13 January 2013 - 09:29 PM

I made a 13" f/5.3 a few years ago and used PLOP for the cell design. The pads were nylon floor glides. It seemed to work nicely.

Regards,
Don

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#34 Mr Magoo

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Posted 13 January 2013 - 10:30 PM

That looks great Don! Thank you for the picture. I would love to see if others want to post them. I'm especially interested in what you use for the pivot points on the bars or triangles.

#35 Arjan

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Posted 14 January 2013 - 02:04 PM

For a single bar pivot point: 1cm dab of silicone.
Mirror can slide loosely though, on ball bearings.
You build the cell on the back of the mirror, use about 2mm thickness of silicone.






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