Flywheel Magnet Recharger
Having found a few engines with weak flywheel magnets I decided to build a magnet recharger. I found the plans to do that in the antique Briggs Service Manual.
The plans aren't real clear, but I thought I could pull it off.
I started by buying the flat stock and round stock for the base, top covers and coil cores. The core ends I cut from floor underlayment board. The pole pieces are a little too critical for me to make in my basement shop, so I'll have them made at a local machine shop.
With the frame parts all drilled and tapped I'm ready to start winding coils. Dan at Albion Machine had the pole pieces done in less that a week. I drilled and tapped them as closely as I could to hold the dimensions required to match the ID of the flywheels they are intended to magnetize.
The 12 gauge solid copper wire was the most expensive component of this project. I bought two 500 foot spools to have enough wire to wind both coils. The second picture shows the progress with one coil wound.
After both coils are wound the pole pieces are adjusted to get the 5.975 to 5.980 OD required for .020 to .025 clearance on the ID of a 6" flywheel. When I drilled the base plate I slotted the hole on one side to allow for this adjustment. It took some bumping around and shimming to get it all squared up and on size.
Next thing was to build a wood base for the components to be mounted on. These pictures show the completed base drilled to accept all the parts. This thing will be heavy once it's all done so I cut hand holes in the sides to allow for a good lifting grip.
Here all of the components have been mounted to the base. The picture on the left shows both pole pieces mounted. That configuration will be used to charge small flywheels. The center picture shows the back side with only the 6" pole pieces. That would be used for charging the larger flywheels. That view also shows the power connection points. I plan to use a portable jumpstart pack for power. The bottom view shows the wiring.
With the power applied the polarity is checked with a compass. The North pole is then clearly marked. The charger is finished.
A small flywheel is stood up on end with the magnets resting on the small pole pieces with the front of the flywheel facing forward. To charge a large flywheel to top pole pieces are removed. The back side of the flywheel had an "N" marking the North pole magnet. It is set onto the charger with that North magnet on the North coil of the charger. The actual charging process involves applying current twice for 3 seconds with 1 second between them. Not much to it, but it will bring life back to a dead flywheel. An engine that was picked up at a scrap yard was most moved with a larger magnetic crane at some point. That alone will kill a flywheel magnet.