I was out of town this week, so I wanted to cast something that could be useful for my final project ideas.    So I tried to make a motor shaft coupler.   With leftover material, I also cast a section of tin ceiling tile, a plotter pen holder, and a gear-belt pulley.
Shaft Coupler


How it happened:

   In importing the part from Rhino to inventor, the units got lost.     Eventually (with help from of one of the lab TA's I managed to get a part of the correct size.

   Milling on the Modella, the initial rough cut took close to an hour.   I then spent a few hours playing with final cut parameters.    The final cut still appeared rough, and may have made the critical surfaces of the master rougher.      Initially I used a ball mill, but moving to flat mill made only a limited difference.
milling wax
    The camm algorithm in the Fablab modules seem to take a pretty simple approach, and does not follow the features of the part carefully (to produce fine details).   (i.e. circular patterns not in it's preferred plane come out striped.

   Molding one half of the shaft coupler ended up with an air bubble in the shaft hole.   Didn't mold cleanly.
pouring rubber
   The hydrostone/drystone are much stronger than other plaster-like substances I have worked with in the past.    They do machine, but not real well.   I tried drilling and facing.   Parts are brittle, and the powder is probably bad for the lathe.    It is a quick/cheap way to verify that the parts came out ok.

   Thin tabs/features tended to break off.    For the parts I'm building, the thin parts that broke didn't matter.
casting process
   I had extra casting material, so I tried to reproduce a pen holder for my plotter, a gear belt pulley, and a piece of our kitchen celeing.   The parts are shown below.
   The pen holder was doing ok until the lathe... then it split apart.
broken pen holder