The Antikythera Mechanism 6: Jupiter, and Beyond The Infinite

The mechanism is now really taking shape. I did more work to stabilize the back gear. One change was to add a rim on the top of the midplate which the b1 gear can rest on. This made a lot of difference and once I had done it, the mechanism began to move more smoothly. Both the inferior planets and the superior planets have a gear that must be fixed and so some work was needed to anchor them indirectly to the midplate and backplate. It's a bit hacky as present, as I hadn't thought ahead about how to do it, and so I used extra bits of framing that could be attached to the midplate. A redesign will follow.

I also made the decision to use brass tubes for the outputs instead of printing them. The thinnest tubes are the longest ones and so hard to print accurately as well as being fragile. The brass tubes I selected have diameters from 4mm to 11mm in 1mm steps, and they have walls 0.45mm thick. They are a snug fit but able to move freely. Some of the tubes came from K&S Metals, others from Albion Alloys, and I bought them from Macc Models in Macclesfield, England. Here's how they look (the middle 4mm one is not yet cut to size):

You can also see that the top frame had to be split into two to fit the printer. The superior plate is just underneath it, and with a bit of creative truncation it will just fit on the MK4 print bed.

Here is the mechanism running without and with the output pointers. You can see the retrograde motion.

The long "dragon" hand looks odd to me, and I'll check that later.

The next step will be to add the moon phase. At this point I can cut the 4mm brass tube and the (currently hidden) 3mm brass rod that connected with b3 to size. Freeth argues that the hands should have their tips in the same plane to avoid parallax; I might also do that later. The back pointers with the spiral Metonic and Saros dial are also still waiting.