I made a jig for cutting the conduit with the lengths and angle set to allow fast cutting of all 165 struts.
All of the 'C' struts (longest ones) after they have been cut but before the cable tie holes were drilled.
Another jig was made to fit the angled struts against so that the cable tie holes would be drilled at a consistent length from the end.
An example of a drilled strut, note the cable tie hole is angled the same as the strut end itself.
Making sure I get the holes drilled in the same orientation on both ends.
All 165 completed struts with each of the 3 lengths marked with different colours of electrical tape.
61 completed hub centres.
Here's the jig for cutting the outer parts of the hub, which I cut to 40mm lengths. My circular saw was not big enough for this, so I had to revert to hand tools. This was the hardest part of the build.
Here's a pile of about half the outer hubs, before drilling.
Yet another jig, this time so I could drill through the 110mm pipe without deforming it.
Drilling 20mm holes in the hubs, I needed 15 with 4 holes in which will form the base, 6 x 5 way connectors and 40 with 6 holes. Ordinarily a 3V dome's 6 way connectors are not all 60 degrees apart, but again I guessed that the the material would be forgiving enough, so all angles on the 6 way connectors were exactly 60 degrees.
All the outer hubs completed, by far the most time consuming part of the whole fabrication. Okay that's everything made, now on to building the dome itself.
I did a test build in my back garden to see how long it would take me to do it on my own. It took around 2.5 hours for this first attempt. Here is the first layer completed and self supporting.
And the second layer...
Now for the third layer which is almost complete in this picture, I'll be needing a ladder to finish tying those hubs together.
Looking up through the top of the dome. See those clouds? Yes, this is England and that is a normal sky around these parts, which is terrible for amateur astronomers like me. Hence the motivation to build a planetarium in the first place!
This is the dome in its new home, which is inside a 130 year old disused underground water reservoir. There is 6 metres of headroom here, which gives plenty of room for raising the dome above head height once it has been covered.
