Work has begun on the CNC dremel tool. Today I attempted to pour the first piece for the machine. Of course, I chose the most complicated part in the whole design. The hope was that today's pour would result in the carriage for the Z-axis, which will hold the dremel clamps and the roller bearings for the Z.
To begin, on Sunday I hacked a pattern out of pink foam. The outside surfaces of the part came out well, since they could be cut with the bandsaw. The interior was a different story. Since I tried to make the part from a single chunk of foam (actually 2-1" pieces laminated together), I had to gouge and hack the interior out. It won't be seen on the finished machine, so I wasn't too worried about the appearance.
Once the foam pattern was done, I coated it with drywall mud and left that to dry overnight.
Today, I fired up the furnace, buried the pattern in sand, and gave it a shot. What a disaster! One runner didn't connect, another was very contricted, and it appears that either I didn't pour fast enough, or the sand/mud got into some places it wasn't supposed to. The casting didn't fill completely and had some mysterious pockets on the face that was at the bottom of the part.
