*
Monday 17th, 38F, gales and some sunshine. The NW wind is on the back of the dome if I wanted to do some imaging.Today's priority is building some stays for the top guide rail channel. I went off the idea of using some existing box section aluminium. The wall thickness really wasn't adequate to the task. Not when using my tabs idea. I had planned to cut away a rectangular section of tube to leave just one wall as a fixing tab. However, the considerable weight of each shutter deserves far more reliable support. Aluminium readily work hardens with flexure. A recipe for disaster!
What I do not like is the cosmetic appearance. It is neat enough, in itself, but just doesn't look the part being so exposed on top of my observatory dome. Then I had the idea of sleeving the steel strip with the original aluminium box section tube. Strength with smartness? We shall see.
The perforated steel strip was not remotely stiff enough to do anything useful. Even though it felt stiff in the hands. It simply bowed under compression. The angles required for fixings were also quite complex. Meaning that a much stiffer strip would need compound angles to lie flat on the dome. The perforated strip was thus a useful tool. To help me judge the requirements, angles and dimensions.
Later I applied inverted imagination. The top channel stays can be in tension. I just need to fix supporting blocks, for the channel, as far outboard as possible. Or, I can add a vertical strut from the central bolt up to the channel.
*
No comments:
Post a Comment