| Electronics > Beginners |
| Think I can make it? (electric 9-pole radial engine replica) |
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| metrologist:
I am using Adobe Illustrator. Do you know if the flux would be the same as you've drawn it if there was no structure? Magnets and coils floating in space. I was considering it that way because I am using aluminum. |
| Gregg:
If all the coils are mounted independently it would be much better than the ring of magnetic material near the rotor. Air has some magnetic permeability; about the same as aluminum, wood or many plastics. Iron has many orders of magnitude better permeability which would cause the magnetic flux to follow along the path of greater permeability rather than interact with other magnetic fields like the permanent magnets. A quick Google search for magnetic permeability will show some interesting results. The problem with aluminum in close proximity to changing free magnetic flux (flux not being directed by a medium of much greater permeability) is that aluminum is such a good electrical conductor that eddy currents will be generated in the aluminum by the changing fields of the electromagnets which will cause heating because they are essentially short circuit and will need more current to overcome this loss. To demonstrate this, try dropping one of your small magnets through a similar ID copper tube and note how long it takes to fall. Plastic would be a better material; using something like Delrin you wouldn’t need shaft bearings. |
| metrologist:
I have black Delrin. I think I'll still give it a whirl with the aluminum body and later compare with Delrin. The aluminum is already chucked and the roughing started a couple days ago. Hope I have some suitable screws. |
| Gregg:
Nails cut to length may make good cores for the coil and they are cheap, easy to chuck up and power wind the wire prior to cutting them to length. The sheetmetal laminate plates you mentioned earlier may be a little more efficient, but what a pain for winding coils |
| metrologist:
I was thinking 16 turns. But I would need a continuous wind between 3 cylinders. I was just going to wrap the single wire manually, but I think to get the wires to lay down nice, I'd need to wind all three runs at the same time, from cyl to cyl... |
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