Sunday, December 9, 2012
08 Joint Design Nº 32
This is a method of finding the center of a sphere. I cut a pencil to expose the lead. I taped the pencil to a combination square, with the exposed lead facing out. I made a coil of clay and formed it into a circle. I placed the 40mm ping-pong ball that I am going to mold on the circle of clay to keep it from moving. Note that the circle of clay is smaller in diameter than the ping-pong ball. This is so the clay will not interfere with the square. Finally, I move the ping-pong ball around with the edge touching the pencil lead. A mark is left at the diameter of the ping-pong ball. Click on any image to enlarge it.
Using a piece of scrap matte board, I mark the center, then use a compass to mark a circle 40mm in diameter, which is the same as the ping-pong ball.
I use an X-Acto knife and a couple of pieces of cereal box cardboard to cut out the circle.
The ping-pong ball fits inside the circle I cut out.
This time, the circle I cut is just a little too big, and the ping-pong ball slips through it easily. I am going to tape it into place with some masking tape.
This is the under side of the matte board, showing the ping-pong ball taped into place.
This work is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.