Homebrewed Electricity > Frequently Asked Questions (FAQs)

solid or laminated magnet rotor?

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collidog:
solid disc magnet rotor or laminated thin sheets as in transformers? I have tried building up rotor thickness gradually and measuring results. Initial results indicate  similarities with varying magnet/ coil gap, i.e. rotor speed increases to provide a fixed final power into a resistive load. Is this the expected result?

hiker:
solid steel mag rotors....no need for laminated on rotors...laminated ...is used  for the coils..on motors..and gens that are built like motors..

collidog:
  Thanks for that. Let me reword the question slightly.
  Are there any DISADVANTAGES to using laminated rotors? (axial flux type, of course). I do not have the facilities to machine solid rotors, so some years ago when I began practical experiments, I used tinplate that I could cut with tinsnips then laminate the discs to required thickness, using various methods.  By gradually building up the thickness, this gave me a "real-world" awareness of how adjusting rotor thickness to magnet strength affected power output. I also wanted to minimise rotor weight and thus lower starting  inertia. If solid rotors have been proven in practice to be more efficient electrically rather than merely convenient for the car disc brake aficionados, then for my own convenience I shall have to live with it. Perhaps practical comparisons have not been made?

electrondady1:
i found 10" table saw blades to work OK as rotors for ferrite mags.
if your using neo mags, you will need multiple layers of blades to contain the magnetic flux.
you can test with something like a paper clip on the back side to see is it wants to stick.
if it does you need more steel.

collidog:
  Thanks for responses so far but let me rephrase the question again.
 If transformers use laminated cores to reduce eddy currents, as do electric motors, then unless there are no eddy currents in axial flux magnet rotors (expert opinion, please) surely laminated rotors would be beneficial, especially if the laminations were insulated from each other?

P.S. I do know about saw blades and paperclips. I have spent many interesting hours hunting through the forums

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