The slot

This was something I have been looking forward to and dreading for a while. Whilst I had a plan in my head for a long time that I wanted a fully sliding door, A lot of it just happened as I went along. I decided on 30 inches wide for my 11 inch Schmidt-Cassegrain telescope (SCT) and started the cut one triangle up, (horizon) and all the way to a bit over half the width of my SCT, past the azimuth, (8 inches). I used a tape measure to mark and rule a centre line, then measured 15 inches either side. This proved quite hard as the measurements have to follow the contours of the dome, not as the crow flies. I then placed one of the left-over arcs I had cut, lined it up with the marks, and used it as a guide for a pencil to mark a line for cutting. Look at this heaps and think on it before you cut anything!! Look at it from a few angles.

The frame for the slot was made from the second large circle made of multiple layers of ply. (3) Measure the side of the slot and make sure you cut a little bit more arc than you need. Better to cut off a bit than have to add a bit. Cut wood to form box ends on it then fit it in the cut hole. Screw batons into the sides of the frame under the skin of the dome, then screw the skin down onto the batons from the outside. I lined the edge of the frame with some zinc-alum strips. This will make the door slide a lot easier.

If you were like me, in a hurry to put it all together, you may find that you will have to dress a few inaccuracies up later. This can be difficult after assembly, but if you don't want to risk taking things apart again, there are ways....

Take, for example, the un routered edges of the sides of the slot. Mine were circular, but pretty rough. Through a bit of ingenuity, a router can be fixed to a vertical pivot point and run along the edge to tidy up. Check out the following images for a better understanding.