lightweight focuser.

I am thinking about changing out the 1.25" focuser on my home made 6" f5 scope for something in 2", so I can get even wider views. The main problem is weight. A secondary problem is cost. What would be the best lightweight focuser for this? Helical? Is there anything I could make myself (without ready access to a machine shop)?

Thanks,
Charlie

Attached Image:

My recommendation:

http://www.kineoptics.com/HC-2.html

Your existing focuser looks a little tall, so you might want some kind of interface plate between the HC-2 and the cage to put the focal plane at the right place. Not sure, but it should be easy to adapt in any case. Getting farther back is always easier than getting closer in.
--
Mike

I'll second what Mike said about the HC-2. I have a couple and they are good units. The DAR double helical is nice too but is a little heavy.
Bill in SA

One odd choice is to hit the marine supply shops. A nylon drain plug can be had in the 2" to 4" Interior Diameter size range. My first one was a 1 3/4" for 1.25" EP's but a 2 1/2" would have been jsut as easy.

These screw closely enough to be useful, if you add some plumbers tape. Very smooth feel. A 4" finger wheel up top makes the action silky.

Make appropriate adapters to cut the size down to fit 1.25" or 2" EP barrels. You'll want a wood lathe. But....

I cheat: a drill press, 1" work head up top (or a V-shape screw in a pre-drilled hole will do), and a pivot head at the bottom. With soft pine wood the chisel cuts right through with the rotation set in the mid range. When the work's down to 1/8"-big, go to a 40 grit block then smooth it out from 1/32" to perfect. You get the idea...

The inside hole can be cut a little big. Then lined with felt. Lots of ways to skin the cat. EP's don't need screws to be happy.

You have a little work with a Dremel to make necessary modifications to the original nylon drain plug. Cutting off unnecessary formed parts. Maybe a quarter-hour's work.

5 minutes for the second one.

These drain plugs are a bit difficult to aim properly. Amateurs, wrong tools, etc. Errors happen. If your hole is drilled perfectly, that's a help; it's not absolutely required.

One "cure" is to insert the adapter in the drain plug body -- made to home drill press accuracy, remember. Then insert a pipe of the right diameter and a foot long into the adapter. Then you can measure to points equidistant from the edges of the main hole.

Straight enough.

When the screws at the base get it to look really good, make the installation permanent with plumbers epoxy.

Cost's about $5 - $10 total. Gets very low profile, great longevity, nice feel. Nylon's wonderful stuff.

And if there are any problems at all, ever, it's my fault. Not yours......;^)