The Walls Go Up

Up until now we have essentially built a deck, now it's time to go up!  But how far?

There are competing design criteria here, higher walls means a taller door which makes for more comfortable ingress and egress but walls that are too tall either impinge on the field of view of the telescope or require a taller pier which then means you need steps to get to the eyepiece which can be problematic in its own right. I figured the most important things is to be able to use the telescope with the least difficulty possible since I will spend a lot more time using the scope than the door!  For me this meant the scope being about 1.6m above the floor in the horizontal position so I set the wall height at 1.5m to allow for the running ring and the rolling structure of the dome.   

Here we find yet another reason not to build a decagon... You have to build more walls!

There are a huge number of ways to build walls depending on your skill level and appetite for doing carpentry.  To keep things as simple as possible I opted to build simple butt jointed frames, one for each section of the decagon plus six more for the storage pods giving a total of sixteen panels, four joints on each panel: sixty four joints to be made... Best get on with it then.

As I have mentioned before my carpentry skills are rudimentary, this and the fact that I needed all the walls in place quickly so they could be fixed together led me to use nail plates to join the timbers rather than trying to make nice joinery.   A word of caution though, whatever method you chose, make yourself a jig to work to, it is all too easy to make your frames skew when you are bashing away with a lump hammer!   Conscious that some of the spans were bigger than others I also added supporting timbers in the middle of some of the frames.

Each of the wall frames was in turn screwed down onto the floor then to its neighbour in the picture you can also the temporary bracing timbers used to steady the frames while I worked on them.  Because these frames will not be visible from the outside I wasn't overly worried about the occasional gap between frames, these will be covered by the exterior cladding later on, what is important is that they be plumb, that is they must be straight up and down otherwise you will set yourself up for big problems when it comes to supporting the dome.

I would also like to take a moment to talk about the storage pods here, I made these the same height as the rest of the walls, that was a mistake, a much better idea would be to make them a little lower so that you can add a sloping roof to them I have had to put flat roofs on mine which may be a problem in heavy rain, we shall see!

All in all the walls went up pretty quickly, they may not be the prettiest but they are up and now we can move onto the most challenging part of the construction: the running ring.