Telescope Reviews: My thread for building a 12.5" RC.

Hi all, I thought I would start a thread now I am getting in to the project a little.

I have to say that it's tough work finding a lot of cassegrain information on the web. I know there are people making them but not a lot of documentation floating about, nor pretty pictures

Anyway, a brief history about my project.. I came across Star instruments and found I could buy a 12.5" set of RC optics for much less then I imagined. I had only seen the commercial prices for the finished product - too much for me I am afraid.

This set of optics is the 12.5" astrograph, it's cheaper then their professional series and a bit of a gamble as I have yet to see pictures out of a completed set. I think his reputation and that he provides optics to RCOS was enough for me to go on.

Well I got an email saying they are on their way, only a week to go before I can look at them - a long way from using them though.

Time to get off my chair and start making bits! I had already decided that I would do a carbon truss design. As this is my first cass I am copying what I can see in other designs.

My only two problems that I will need to sort out is how big a spider and vanes do I need to support the 6" secondary - without over engineering it too much.

The other is I need to find out more information about supporting the primary. I have done a 16" dob with a 18 point cell. I know I cant use this type of support (the sling). I plan on doing a 9 point flotation system - I just need to figure out how you stop it rolling around without asserting too much pressure on the sides.

I have found it really tough finding good pictures of primary mirror supports for a cass.

Anyway, by the end of this I will have found it out and documented for others..

Please, if you are doing a project like this yourself jump in and tell me how its going, I wont consider it hijacking!

Not a lot of progress to date but I will put some pictures on as things happen. I am going to build this out of aluminium which is quite costly, its a shame when you think most of it turns in to shavings... I don't want to get something wrong on a $100 piece of plate so I am mocking the frame up in wood first, once assembled I will machine the wooden bits in alloy.

I will do the floatation, connectors, spider etc all in alloy, no need to waste time mocking those up, the wooden frame is so I can get happy with the layout and design. Its only used about 2 hrs to do the wooden pieces so its worth it to me.

pictures so far...

Post Extras