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Picture of Smaller Dobsonian telescope
I was been missing making a telescope, but didn't need another one. So I persuaded a colleague to make one with me. The optics were cheap--a 6" F/5 mirror (with a 1.5" secondary) from a Cloudy Nights seller for about $60. In classic style, this was going to be mounted in a Sonotube, with most of the rest made of 1/2" Baltic Birch plywood.

Step 1: Altitude bearings

Picture of Altitude bearings
I used a router to cut altitude bearings from 3/4" red oak. They are slightly more than semicircles. It's traditional for altitude bearings to be circular, but using semicircles (or slightly more), the radius could be made larger for semicircular bearings without wasting money on a wider board, thereby making for greater stability. Moreover, it's easier to cut less than full circles on my fixed-base router. And I cut lightening holes with a hole saw.
 
What was the total cost of the telescope? What can it see well in particular? I'd really appreciate it. Thanks!
arpruss (author)  Mithrandir131 month ago
The main cost were the mirrors, which were about $60-100, from a seller on cloudynights. Can't remember exactly. The rest is cardboard tubing ($10), Baltic birch plywood (cheap around here at around $40 per 5'x5'x0.25 sheet -- I still have leftovers from that sheet!), a bit of teflon, and miscellaneous hardware. Maybe the total comes to about $150-200?

Collimation may be an issue, as with all Newtonians. I built a laser collimator for about $10.

You could probably get a used telescope on craigslist for that much or less, and maybe a better one, but it's fun to build.

What can you see? Planets, the moon, globular clusters, certainly. Dimmer things? Depends on how dark the skies are. But you can certainly see quite a lot of nice stuff if you have dark skies.

That said, I haven't really used this scope except when doing some quick initial testing, since it was for a friend.
Thanks! I've been wondering the cost effectivity of
home-built telescopes and so far it looks like it all depends
on the mirror cost. I have plenty of free plywood, the cardboard
is pretty cheap, and the project doesn't seem too difficult, I will
definitely have to consider this!
arpruss (author)  Mithrandir131 month ago

I forgot about the springs for the cell. I've been really happy with mower engine valve springs. You can get them cheap or free from a local small engine repair shop.

arpruss (author)  Mithrandir131 month ago

Here's a mirror set pretty much like the one I got for $65+shipping:

http://www.cloudynights.com/classifieds/item/53076...

If that's sold out, PM user MASILMW. Back when I did telescope building (haven't done it for a while) he had a lot of cheap mirrors, occasionally with defects that he would honestly report and lower the price for. (I have a nice 8" F/4 mirror, I think from him, where I had to black out a region. The scope is still nice.)

As him what he has in the 6-8" range.

This is amazing. I'd never heard of a Dobsonian before, but you've inspired me to do some more research from home.