I Explain Permanent Magnet While Spinning My Saw Blade Windmill

Hook

I explain permanent magnet orientation on this saw blade windmill because the overlapping sideways magnets are doing something interesting with their poles. Less is more, but sometimes you need just the right magnet pull to make it float and spin for ages.

Watch this experiment

I threw the saw blade onto the levitating pole, gave it a spin, and watched it coast. You can see the weak edge poles interacting, the disc slowly turning, and the moment three donut magnets on the base circle suddenly make it stronger in one direction. Nothing fancy — just a pole, some magnets, and a lot of trial and error.

What you'll learn

You’ll see why north-south alternating layouts can be a total bomb, how overlapping magnets disguise the poles, and why I’m betting on a 9-section or 8-with-9-magnet setup next. Plus the difference a little levitation makes when you want long spin times.

From the bench

Everything you see is stuff I already had in the shop. The saw blade has sideways magnets overlapping so two weak poles protrude from the edge. I tried turning them all face-up for full north or south but kept coming back to the overlapping style. The base is an 8-inch disc holding the whole thing up on a central pole. I don’t have a lot of tools right now so I’m working with what fits and balances.

How it works / what we changed

I explain permanent magnet poles by showing how face-down overlapping magnets still let north and south peek out at the rim. That gives the weak push-pull I’m after for this windmill idea. Earlier north-south alternating on the full circle was a complete failure — it just fought itself. So I switched to thinking in sections of eight or nine magnets. 72 lines coming off the center makes nice 5-degree steps. I drum two at a time so I’m really working with 36 lines. The levitating pole cuts friction way down; once it’s balanced the smallest magnet pull keeps it turning a surprisingly long time.

Magnet pull

The magnet pull on this rig is weak but enough to keep the blade spinning once it’s levitating and balanced on the pole. When I added the three donut magnets in a circle on the ground the pull got noticeably stronger in the direction I normally spin it. I could see the blade raise up a little when the last magnet got close — that’s the pull I want. It’s not strong enough to suck magnets off the disc unless you flip one the wrong way, but it’s perfect for a low-friction windmill that coasts for many rotations after one good flick.

U magnet

I didn’t have a U magnet on the bench for this test so I can’t give you direct measurements. The closest thing was the curved pull when I placed donut magnets facing inward on the base circle. A U magnet would probably concentrate the field more than the flat disc magnets I used, but right now I’m sticking with what I have. The overlapping sideways magnets on the blade already act a bit like distributed poles so a U magnet might be overkill or might fight the edge poles — I’ll have to try one later and compare.

Magnet group

My magnet group right now is eight or nine magnets per section on the 8-inch disc. I tried a full north-south-north-south circle and it was a total bomb. The new plan is either eight sections of nine magnets or nine sections because 72 lines gives clean 5-degree spacing. I’m getting 9-inch discs soon and will lay out a 369 pattern. The current group of three donut magnets on the ground circle gave the best spin so far. When the ninth magnet in a levitating group is positioned right I think the whole thing will balance and float nicely.

Builder checklist

• Start with a balanced central pole for levitation
• Overlap magnets sideways on the disc so two weak poles protrude from the edge
• Try 8 or 9 magnets per section — 72 total lines is a good target
• Test spin direction — one way was clearly stronger with the donut base magnets
• Keep extra magnets handy in case you need to flip polarity or add pull
• Use graphite lubricant if the pole needs a little help

Troubleshooting

If your saw blade windmill stops quickly, check balance on the pole first. Mine lost speed only very slowly once levitating. North-south alternating layouts can fight each other — I scrapped that after one try. If the magnet pull feels too weak, add the three donut magnets in a circle on the base; that helped a lot in one direction. When magnets get sucked off, you probably placed one facing the wrong way. I moved one magnet over a little because the others were slightly off and it leveled out the spin.

Safety

These magnets are strong enough to pinch fingers or yank the whole disc off the pole if you bring the wrong pole close. I almost lost a set when I flipped one the wrong way. Keep loose magnets away from the spinning blade. The levitating setup is stable but can wobble at high speed so don’t stand directly over it while testing. No electricity in this test but future pulse-motor versions will need the usual battery and coil precautions.

FAQ

Why overlap the magnets sideways instead of facing out?

It disguises the full pole strength and gives two weak poles at the edge — exactly what I wanted for this slow methodical spin.

How long does it actually spin?

After one good wrist flick it went around like 15 times on the Price-is-Right style slow wind-down. Levitation makes the difference.

Will a 369 layout be better?

I have 3-inch, 6-inch and 9-inch discs coming. The 9-8 combination on the bigger discs should let the sections sit close enough to balance and levitate nicely.

Do you need tools to build this?

I’m doing it without a proper shop right now. If the hole and bearings are the right size the levitation does most of the work.

Related on this site

• How to Build a Pulse Motor: Complete Beginner's Guide
• Pulse Motor Rotor Design: Magnets, Materials and Balance
• Magnetic Levitation on a Pole – Experiment 1: Push, Pull & Balance
• Hanging in the Balance: Levitation, Permanent Magnet Style
• Donut Magnets — Outside Poles & Motion
• Less Is More — Clockwise vs Counterclockwise

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