Dec 032012

With it becoming increasingly more and more difficult getting in and out of the dome (slithering on my belly is loosing its appeal), I relented and broke out the power tools and proceeded to create a door in the rear of the dome.

I had to cut off 6 of the metal strips from the bottom hub 3s, and the middle hub 4s and the top hub 1s. This was done to ensure that the door is able to swing freely on its hinges, but not fold into the dome,  placing strain on the wooden beam holding the door in place, and potentially tearing the screws from the wood. To ensure that the door could open easily, I cut off 7mm from the top of the all A-sized struts radiating from the door’s hub 2.

Now all that is left is to seal the wood, and to mount the door.


Dec 032012

Christmas has come early, with the supplier delivering my first order of Marlon multiwall polycarbonate sheeting.

The supplier I used is Duroplastic, based in Johannesburg. I can really recommend them as their service was fast and professional, and their driver was extremely pleasant person to deal with. Thanks Duroplastic! They can be reached at

Dec 052012

Yesterday saw me creating the first of five window frames that gets installed in the triangular space between the two hub 1s, on the third tier of the dome. The cutting of the wood was rather tricky, but I managed to do a half-decent job.

The window opening was measured and each side was 700mm. Now maths teaches us that triangles of equal length are called equilateral triangles, and all the internal angles are the same. So each corner must be 60 degrees.

My daughter and I fed left-over planks through the table saw, and cut strips of 15mm x 32mm x 1m. From there we measured out three planks and marked off the 700mm mark and once again it was back to the table saw, to cut a 60 degree angle, but at a 8 degree camber. Once the lengths were cut, they lined up neatly. I now needed to add in a spacer to give the window a perfect fit.

Breaking out the mitre saw, I cut a 2.5cm piece of the 15mm x 32mm x 1m wood with a 12 degree angle and a 12 degree camber on both ends. This was then placed between two corners and tacked together with 1.6mm panel pins. I will either opt for a wood filler or simply mix saw dust with cold glue to get a smoother finish around the joins.

With the hinges attached, it is now time to varnish the first window frame and then to install it.

Once the dome is complete and the Arduino is installed, the Arduino will be taking frequent temperature measurements, and should the dome get too hot, the Arduino will drive a small servo motor and open the windows automatically, and close the windows when the temperature returns to normal.

Dec 062012

Finally I have completed all the window frames, and given them a coating of varnish. I would have fitted them to the dome but it had started to rain, so I will do it tomorrow.

You will note that the hinges are placed on the outside of the frame. When I was testing the design, the heads of the screws kept on pushing against each other thus preventing the windows from closing properly.

Completed window frames drying

Dec 082012

Today I completed installing the window frames and installing the door to the dome (pictures will follow tomorrow). I also fabricated the jig I will be using to trace the various triangles onto the plastic so that I can cut them out, using a circular saw and a very fine toothed blade. The jig was created with three pieces of 30mmx3mmx800mm flat bar, which I cleaned up and cut a slot into the top and the bottom of the bar. I installed a screw and nut at both ends, which allows the triangle to be sized.

To use the jig, it gets placed against one of the triangles, and then gets aligned so that it masks off the top half of the wooden strut, exposing the triangle and half of the wooden strut. The nuts then gets tightened and the jig is then transferred onto the plastic where the shape is traced and then cut out.

Dec 092012

Here are the pictures of the installed and working door, together with the five windows, which together with the Arduino, will help keep the temperature inside the dome under control.