Rotocasting

DonS

Well-Known Member
Heya,

Been working on a rotocasting machine for some time, finally got it to the point where I could do some casting. The first version of the machine used a gear and pulley setup to drive the inner frame but that didn't work out...too much slop in my construction to keep the gears properly meshed. In hindsight, I think the gears I chose were too small for the job and the tolerances too tight. As you can see from the pics, this a somewhat large machine, built of 2x4s and 4x4s, that stands nearly four feet tall. I overbuilt it as I have some molds about the size of a breadbox that weigh maybe 50 pounds. Anyway, once I switched to a motor-driven inner frame everything came together. The trick was using a slip ring to pass the inner frame motor wiring through the outer frame to the electrical plug.

For the first test I used some resin that had been sitting on the shelf for about 4 years. The castings were uniform but there were too many little voids for my liking. For the next attempt, tried some fresh resin but it kicked over too fast, faster than the specs indicated it should...wound up with a solid chunk of resin sitting in the bottom of the mold (but the detail was perfect). For the third cast, shown here, I tried the old resin again but ran a dehumidifier in the basement for 12 hours, warmed the mold in the microwave and dusted the inside with baby powder. Couldn't be more pleased with the outcome. Perfectly uniform parts with great detail and very few imperfections. The resin used was from Aeromarine products. Even after sitting all that time, the material gave excellent results. The only drawback is that it's $20 a gallon more expensive than Smooth On 305, which I'll be trying next. I plan on needing dozens of gallons, so $20 per adds up. But if I can't get the results I need, I'll stick with Aeromarine as I know it works for needs.

I'd like to thank everyone on forums and websites like this where experienced people share there knowledge. Without the research I did, things wouldn't have gone so smoothly with so few problems. The mistakes I made were my own; the successes largely due to knowledge shared by others.

D.
 

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Thanks!

It's turning out to be a pretty useful piece of equipment...some previously solid cast parts I'm using will definitely be slush cast from now on.
 
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