I started back up on the design of the mold machine this week. A few major changes have been made:
- Instead of using a piston pump to move the molten plastic from the melt tank to the mold I am using an external gear oil pump. The plastic I’m using has a melt viscosity similar to that of cold oil, so the pump should be capable of transferring the plastic.
- I have also fleshed out the melt pot mounting details and devised a new valve body that incorporates the oil pump mount. The pump is driven by a right angle gear motor. This will make the shot size easily adjustable.
- A refill hopper, auger, and pot stirrer have been added to the rear of the machine.
- Some of the larger subassemblies (water chiller, air tank, compressor, power supply) have been added to gauge enclosure size. I’m still shooting for coffee table sized, but finding a refrigerant based chiller the size of a shoe box is difficult. A much smaller option would be a thermoelectric (peltier) based chiller, but the heat input into the system from cooling the plastic (about 250W) and the ~2 gal water capacity is a little out of the range of most thermoelectric chillers. Not to mention they are very inefficient.
I’m going to continue to refine mounting details for a few weeks or so. In the mean time I am tracking down parts: 100rpm right angle gear motor, <1/4hp aquarium chiller, air solenoid manifold, oilless compressor, and air cylinders. Some of the parts above may change depending on what I can find at surplus shops/eBay.