Finally got around to machining the castings I made for the FIRST Robotics team CNC router. I screwed up not allowing enough for shrinkage but managed to adjust the machining on mating parts to compensate. A fair amount of machining and tapping on all the parts and I was pleasantly surprised by having almost no porosity. Looking forward to more casting when the weather clears up.
Good to hear Gary. Glad they worked out well. I'm waiting for a break in the weather myself to pour a couple lost foam castings. Meanwhile, I heated treated and started machining several lathe pulleys I previously cast. The little lathe is making it's own future power train. http://forums.thehomefoundry.org/index.php?threads/lathe-motor-and-countershaft-pulleys.1399/ They only got a T5'ish heat treatment but when tapped with a ruler they went from a dull metallic thud before HT, to ringing like a bell after. I did this in my electric furnace but it can be achieved in a household oven if it doesn't cause divorce. As long as they are heat treatable alloy, it will significantly improve mechanical properties, make a big difference in machinability, and reducing aluminum build up on cutter surfaces. Best, Kelly