Cyde Weys Musings

Despite the lack of any progress updates here in awhile, I actually have been slowly working on my telescope. I’ve merely been slowing down because my attention has been diverted by other things (like amateur radio and other miscellaneous projects I haven’t bothered blogging about). So here’s an update on my latest progress. I haven’t touched the mirror since the last update, but I’ve made a bit of progress on the mount. Enjoy the pictures.

The cradle (wooden box) has internal dimensions of just a hair over 10.5″, so the telescope tube can slide in it. It’s 14″ long. Here, I have a section of 10″ PVC pipe clamped to it in preparation for tracing its outline. The PVC section will be what rotates the cradle up and down, providing altitude control.

Here’s the cradle with the outline of the PVC section traced out in preparation for routing the circle. This will allow me to more easily affix the PVC section to the cradle, and ensure that it doesn’t go anywhere. Another circle is traced out on the opposite side.

The cradle after the circle has been routed out (by hand, no fancy central-pivot system or anything). In case you’re unfamiliar, a router is a device somewhat like a drill that allows cutting to a controlled depth and continues cutting during lateral movement. Making it move in a circle isn’t very easy.

Proof that the PVC section actually does fit into the routed out circle. Because neither the circle nor the PVC pipe are perfect, it actually takes a bit of rotating and squeezing the PVC section to get it in there, and once it is in there, it sticks in pretty good. Finding a permanent way to attach it won’t be too difficult.

Using the PVC section to trace out its outline on the top of one of the side pieces. This is what the PVC section will rotate in, providing altitude adjustment.

The final trace that I would begin cutting one. Notice that one of the two curves (the smaller one) is pretty much superfluous.

One of the sides after my first rough cut with the router (admittedly maybe not the best tool for this). You can see that it’s too tight because it’s managing to hold the otherwise unsupported PVC section in place. During the fine cut, I expanded the circle a little bit. It didn’t matter too much that it be perfect, because as you’ll soon see, the PVC section only makes contact with it in two places.

Tracing the outline of the final shape onto the other side piece in preparation for cutting it.

The four Teflon pads after countersinking. A countersink is a special drill bit designed to cut out enough material for the top of a screw to nestle comfortably in. The countersinking in this step is essential, because otherwise the PVC section would be scraping up against the screws as it rotated. Note that screwing in the Teflon is pretty much the only option available; gluing it obviously doesn’t work.

Two of the Teflon pads attached to one of the side pieces. I confirmed that the PVC segment does indeed rotate in it smoothly.

That’s all of the pictures I have for now. Not included in these pictures is the work I did last night: I stained all of the pieces of wood you saw above with a nice Minwax PolyShades stain which simultaneously makes the wood darker in color and seals it with polyurethane for nice weather protection. Now all I have left to do on the mount is to permanently secure the PVC sections to the cradle, assemble the four sections of the main body, construct the azimuth mount for the bottom of the base (which consists of a disc of plywood with feet on the bottom and Teflon pads on the top that the base rotates on), and attach handles to both sections for easier transportation. Oh, and I have to assemble the optics in the tube, which I’ll hopefully do on Friday night.

This entry was posted on Wednesday, March 12th, 2008 at 18:30 and is filed under Telescope Making. Keywords: Tags: alt-azimuth, amateur telescope making, astronomy, mount, router, Science, Telescope Making, woodworking. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.