9 replies to this topic

[Gary Bluestone]

I am trying to remagnetize a K&B motor.

 

One photo shows the rear magnet a twin of the front. My compass shows the strength in the centre of the side plates. I am using a homemade remagnetizer and need help determining the direction of the magnetic field. I have shown two options for remagnetizing but there my be more.

 

If successful I will try one of the MPC Dyn-O-Charger dual-magnet motors

 

 

 

 

[SlotStox#53]

Never heard of anyone zapping those. Biggest question to the people in the "know" are the magnets of a material that can be "zapped" ?

Be good if they could.

[Lone Wolf]

Gary,

I have a modified Super Challenger in a drag car I built. Somewhere here I think I asked about zapping these but I can't locate it. It has a Havlicek arm. I used a motor that I believed was never apart. I was careful not to remove the magnets when I swapped the arm.

I still would like to investigate zapping the car. I wonder if the Super Challenger used better magnets? Who knows.

Maybe you can do a timed before and after run to see if the zap had any effect.

[Gary Bluestone]

I believe the K&B magnets are alnico, and suitable for zapping. The MPC Dyn-O-Charger magnets look more like a ceramic type and I think I read GE had a patent on these. I have some of these that have disintegrated into powder.

[Gary Bluestone]

I did time the car, a Cobra, which ran 8.2 seconds compared with a K&B Ferrari of the same design which ran 7.7 on our Strombecker track of 66 pieces so approx 66 ft.

It will be some time until I can run the car again, and at the same time I cleaned up the front axle drag, sanded the tires, oiled the arm, so I will be faster no matter what.

My only question is, What is the best direction to zap these magnets?

[Ecurie Martini]

Love the DIY magnetizer - haven't seen a selenium rectifier in many years.
 
EM

[boxerdog]

I think in this case the magnetizer needs to contact the front of the front magnet and the rear of the rear magnet. The actual orientation would be determined with a compass.

[dc-65x]

I have successfully re-magnetized twin magnet Bonner motors (similar to the K&B motor) using Steve Okeefe's technique.

 

First I determining the polarity of each magnet. 

 

I use small pieces of steel as a spacers to make the zapper arms directly contact the motor's pole pieces above each side of the magnet.

 

Zap one magnet at a time!!!

[Ramcatlarry]

You can put a 90% certainty that most DC motors will have the magnets oriented with a relation to the brushes. 

You got it right, same with the padlock and Bonner style. The sheet metal parts extend the field to power the armature.  Ring magnets (like Wilson, Globe and RC) get confusing since there is no visible break. Many Pittmans also timed the armatures 90 deg off, but the fields are where the metal is. 

I would shim the assembly to get more direct contact saturation at the magnets... any bit of magnetic iron will do.

[boxerdog]

Regardless of where the brushes are, the field is at 90* to the armature shaft. The set-up shown won't help out, I don't think.

Rick's method, one magnet at a time, is certainly the best and safest. The results are easily measured.