From: andy@pangea.Stanford.EDU (Andy Michael USGS Guest)
Subject: Re: Attaching eyepiece to telescope
Organization: Stanford Univ. Earth Sciences
Date: Fri, 9 Oct 1992 20:50:34 GMT

In article <1992Oct9.183322.18167@pony.Ingres.COM> gmcquary@Ingres.COM (George F. McQuary) writes:
>I've got the tube assembled, the primary mirror mounted, and now suddenly
>I'm faced with mounting the eyepiece. Richard Berry waves his hands somewhat
>at using 1.25" copper tubing for holding the eyepiece, but gives no idea of
>how to attach a tube at 90 degrees to a box. 
>
>I'm using a straight rectangular box for my tube. Any ideas how to mount the
>eyepiece on the side cheaply (Or better methods of making a cheap eyepiece
>mount)?  Has anyone also have any ideas on how to attach stalk mounts to .25"
>plywood?

Here's the Dobson standard eyepiece holder.  It will work for any
eyepiece under 1.5" in diameter.  People who spent more on their NG
Focusers than I probably spent on my 8" have permission to vomit at the
crudity of this idea.

Parts:
about a 3 x 5 inch piece of masonite.  0.25" plywood might do.
The cardboard tube from inside the plastic bags at the grocery store
  (these have 1.5" inner diameters).  I generally take these whenever I
  spot an empty one in the produce department.
A few inch long piece of the 1.5" drain pipe used in bathrooms.  Most
  plumbers have lots of scrap like this.
Some corrogated cardboard strips.

Drill a 1.5" hole in the center of the masonite.

Cut the cardboard tube to the length of a holder you need to get the
focus a bit inside the top of it.  Hopefully you only need a few inches.

Glue the tube to the masonite so the holes line up.

Drill a hole in your telescope where you want the eyepiece to come out that is
just bigger than the outer diameter of the cardboard tube.

Stick the masonite and cardboard tube thingy through the hole in the
telescope with the masonite on the inside of your telescope.  You can
either glue it in place or attach it with three screws which allows
adjustment for collimation.

Wrap enough cardboard scrap around your eyepiece so that it fits snugly
in the drainpipe.  Stick the drainpipe in the cardboard tube and voila
you have a slide focuser.  You might need to either shim the cardboard
tube with paper or sand it out to get a smooth and tight fit.

Blackening the inside of the drainpipe could be a good idea to reduce
reflections.

Cost: should be about 0 unless you can't find scrap pieces.  Then it might
cost you a few bucks.

Ascii drawing:
                                        @@  Eyepiece, wrapped in cardboard
                                       l@@l  Drainpipe tube
                                      |l  l|
                                      |l  l| Cardboard plastic bag tube
                                      |    |
______________________________________|    |____________  telescope wall
                                 -----+    +-----         Masonite


My only complaint with this method is that it takes about 30 seconds to
change eyepieces and since I now am using only 1.25" a more
standardized holder would speed this up.  Hence I am experimenting with
spacers to stick inside the drain tube.

Andy