Take one surplus antenna dish rotor, a 5 gallon plastic bucket, & some scrap wood
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| Top of a test casting from an old big mold, held up to the light. | The vents came out a little thin, but these get reinforced by gribbly louvers. | Some thick blobs in the casting. |
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| The surface Looks to be free of bubbles and pits, all without pressure casting. | The rear vents look a little ruff around the upper deck, the mold may be going bad from hot solid casts. | The hull looks to have warped at the turret mount point. |
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| I dremlled off the bottom of the tank, the pour stub area, its lot of work to do this. | The dish rotor battery. | The 5 gallon generic bucket from HomeDepot, now a casting bucket. |
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| Clip of the roto-casting with only the dish rotor running. | Clip of the dish rotor's mechanics. | Clip of the roto-casting with both motors running. |
| The HeavyDuty windshield wiper motor mounted to the leg of the table (from above). | Side view of the mounted wiper motor. | The dish rotor and bucket assembly flipped up on the hinges for a profile shot. |
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| Homework for future, reinstall the dish rotor into a lighter setup. | ||
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Commercial roto casting machines look to be used by people
casting ceramics or other cement type structures. These machines are usually rated
for 100 lbs loads, and they cost a lot. The
mannetron comes in several
sizes, and the
Protomo
is the smaller machine that plastermaster makes, it's $5,500 U.S. and weighs 350 lbs
shipped. The device I envisioned would be mounted to the end of the casting table I
built and not even have its own stand. I had one extra dish rotor from the J-57 project. The station is rotated by one run at half voltage (6 volts). Based on an online inquire I found most people casting in resin manually rolled their molds to make hollow castings. The most advanced setup was a jig which could be manually rotated, but to which the mold could be mounted/clamped. I like to start something then go off and work on other things. I stay near enough to keep an eye on things so I wanted to make an electric roto caster that I could set and let to cure. My resin is 20 min pot life with 2-4 hour cure. Its goes to goo with in an hour so really the setup can be powered off earlier than the demold times. I have one mold which is huge and produces heavy casts, this we'd like to have hollow, so we can light the hover effect or open up the tank driver's hatch and add a cockpit box. So here are the pictures of a setup I literally hacked together in one night. I gave the cast a test the next day, posted are the pics of the large tank hull I cast in the machine. I put in a mini tank mold and its turret (in another mold). However I tried to pack these in after I had wedged in the big hover tank hull with home 'sill' foam insulation, and they never got a good position, so they kept flopping out. The next day I was out shopping and picked up two lids and smaller 2 gallon bucket from home depot. Using a lid should help keep everything in the pot. Update: I got in two small power window geared motor assemblies, and one heavy duty windshield wiper motor from allelectronics. I'll have to re-work the mount for the roto caster so that it hangs from wood slat it is mounted to now (its already mounted on hinges). This will allow me to mount the W.S. motor to the leg of the table. The motor has an arm with a ball connector on it, this should ride against the board the casting bucket's drive rotor is mounted too. The effect is a rocking motion with the bucket protruding perpendicular to the neutral point. The W.S. motor's a bit violent/loud. It didn't workout. There's something to be said for a good visual example of what is normally an abstract idea. My first experience with this was capacitor leakage in Tesla coil circuit. You hear it and see it in calculations but what does it mean. Seeing electric spark/fingers flowing out from the edges of aluminum foil plates to wrap around the edge of plate glass and meet up with the next plate's fingers is well self evident. In this case the abstract idea of bias is demonstrated. When making calculations with computer software you usually have a round up or round down issue, you pick one and always round that way. The problem is this gives you a bias somewhere above 0, depending on your resolution this can be large. In the casting experiment the center point of the new motor's arm is behind the center point of the casting bucket by 1/4 to 1/2 an inch, but the arm's total throw is no more than 5 inches (I'll measure it tonight). The net effect is a very thin casting for 2/3rds of the casting, and a weird effect that resulted in a partition like wall of resin forming in the forward half of the hull. |
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| Casting type | |
|---|---|
| Regular Smooth Cast 32x | 712 grams |
| Smooth Cast 32x w/Ure-Fil Fillers 0.5:1 mix | 699.5 grams |
| Smooth Cast 322 roto cast | 224.5 grams |
| Smooth Cast 322 roto cast w/bottom removed (pour stub) | 212 grams |
| Paint pot's vacuum chamber lid | Home | |
| PaintPot to Vacuum Chamber, Feed Line | Up |