My new 16" f/4.5 project

marcheenek (Marcin) · #1 17-11-2011, 07:32 AM

I have recently acquired complete optics from Meade Starfinder 16" f4.5 and I am planning to bulid a lightweight truss scope, something resembling new Ultra Compact Obsessions.

Here are the planned dimensions:

Altitude bearing diameter: 32"
Azimuth bearing diameter: 20"
UTA: 22" OD, 19" ID
Spider vanes: two sections of 36" diameter ring.
Baltic birch 0.75"
8 aluminum truss tubes 0.75" OD
Mirror face to the focuser hole" 58"
Height of the focuser when pointed at zenith: ~70" (5'8")

I attached few screenshots of my FreeCAD model.

Any suggestions are more than welcomed!

gmbfilter (Geoff) · #2 17-11-2011, 09:37 AM

Looks delightful
How long do you think it will take?

Rod · #3 17-11-2011, 11:37 PM

Hi Marcin,

Nice drawings! I think the Obsession UC is based on Greg Babcock's 24 inch as described here:

http://synrgistic.com/astro/24inch.htm

I would suggest you look at how Greg has made the base ring larger so that the altitude bearings don't overhang the base. This is a much more stable design, sometimes referred to as a 'flex-rocker'. The idea is to place the azimuth teflon pads directly below the altitude pads so the force is transferred vertically through the ring to the ground. If you google 'flex rocker' you'll see lots of examples.

Rod.

marcheenek (Marcin) · #4 18-11-2011, 01:06 AM

Quote:

Originally Posted by gmbfilter

Looks delightful
How long do you think it will take?

It's a several month project for sure - with the full time job and two kids

Quote:

Originally Posted by Rod

Hi Marcin,

Nice drawings! I think the Obsession UC is based on Greg Babcock's 24 inch as described here:

http://synrgistic.com/astro/24inch.htm

I can't access that link is there an alternate place for that design?

Thanks for your comments.

Rod · #5 18-11-2011, 08:57 AM

Quote:

Originally Posted by marcheenek

It's a several month project for sure - with the full time job and two kids

I can't access that link is there an alternate place for that design?

Thanks for your comments.

That's odd. It works fine for me. There is a picture of it here if you scroll down the page:

http://www.bbastrodesigns.com/osp01/osp01.html

marcheenek (Marcin) · #6 19-11-2011, 01:03 AM

Ok, it works for me now, thanks again for a tip about the flex rocker.
Best