| Electronics > Beginners |
| Think I can make it? (electric 9-pole radial engine replica) |
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| metrologist:
Gregg, thanks for the idea. That would work too. A lot of small parts I'm finding it hard to work with. Another try was to make a flat hub, more like a gear, so the magnets could be oriented with N-S facing poles and have some separation. My tool was a little small so the magnets will not quite fit into the slots. It's also kind of sloppy so I'll make another using a rotary table. I'm adding a pic ture with a US dime for size |
| Gregg:
I just reviewed a recent AvE video where he takes apart a Makita brushless drill. About halfway into the video he has a nice view of the rotor and stator. The rotor has 4 flat neodymium magnets inserted from the side. I thought it may give you additional inspiration. He showed less poles in the rotor than windings in the stator. You are making it smaller than I imagined. The thin brass hobby tubing may be useful. That small I would try making the rotor two piece and glue the magnets in with epoxy and machine the OD down after the epoxy has set. Maybe tap the holes in the non magnetic ring part way to help the epoxy bite, especially if using plastic. I don't envy you winding the coils; I don't see that well anymore. I used to fix clocks without magnification, but not anymore. Good luck on your project and post some pictures or a video of it running. |
| metrologist:
I don't do much without magnification anymore either, but it is proving harder to hold things than see what I'm doing, because I have some optical stuff laying around. Those little magnets are about the size of broken off pencil lead. I got inspired by small things when a lady at work gave me a toothpick that she had whittled into a giraffe - with a tail and 4 legs standing on grass... I still have it somewhere. |
| metrologist:
I got all the holes milled to depth and may make an aluminum ring to press around the circumference to hold the magnets, or I may just super glue them. I have a good idea for the body now too, since the RT is set up... A question or two: I was thinking of using 4 transistors to swap voltage polarity across the windings (12 transistors total). I was going to wire them as Wye, but without the return lines connected together as neutral. The return lines would feed through transistors to ground. I would have pulsed AC square wave, each phase 120° degrees apart. This seems like it would work, but not sure. I attached one phase driver for reference where V2, V3 are out of square wave from mcu. I used an inductor for the winding with 0.1L and 2Ω series resistance. LTspice shows ~1.2A through the coil. If that would work, I have not yet seen how the motor could be wound Delta using the above driver. I'd need 6 connection points so separating each leg looks the same as above. I also have a regular RC speed controller with three wires. How would I convert my driver so it only has three connection points instead of 6? |
| metrologist:
Someone thought it might not work. I decided to use steel pegs shaped like a T for the cylinders, which will be pressed into the body and come closer to the rotor, then wrapped on the outside with motor wire. Then I drew the magnetic fields as I think they are at the start condition, with #1 at top going clockwise. |
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