I apologize for my English. It’s my third language and I have a difficulties finding the right terminology and words for specific subjects like names in math, tool parts, etc. This really slows me down when describing specific tasks.
I’m going back to turning dodecahedrons inside the sphere first. See here. In two inch diameter ball I was able to make up to four layers (including sphere) in small woodturning lathe made by Taig. Its all about good plan and good measurement. I find, making wood balls is best described here. So, i’m skipping this part.
Then carefully and as much precision as possible mark 12 centers on the surface of the sphere. Compass will have to be set at 0.5257 of the diameter of the sphere :) We will never do that kind of accuracy taking in fact that by pinning the wood the distance between compass spikes will make bigger radius. I had to go back and adjust the radius until I was close to 0.5 mm tolerance.
For the first ball I used simple jig to hold the ball. Have to say, I tried to do it on the press drill but I was not happy with the result. Turning ball on the lathe gives you more flexibility with tools, scrapers, sending if needed…
12 holes already made to a depth of the small dodecahedron face. Probably, the end result would be better with small holes drilled to the center. I will explain further down.
I used straight router bits to make the holes. Tape is to mark first hole depth then I used collar placed on the other side of the tailstock to make all 12 holes with the same depth.
In red circle the vertex was still supposed to be attached to a middle dodecahedron. Remember, all holes should have the same depth in order to keep right geometry.
To hold peaces together I had to make a few pegs. Small red line shows why it would be better to drill first small holes to the centre of the ball. Small an big straight bit will never stop at the same depth!
Here is how plug/peg goes in place mainly to hold the small dodecahedron in place when we get to last faces.
Actually, this is the plan for three dodecahedrons inside the sphere I used as a present ( I don’t have a pictures )
. Preview of the next blog. New ball chuck and five layer ball
If I missed something here I will try to reveal it in the next blog
-- Live to Learn