Hey all. Who have used rare earth magnets to repower your motors. Where did younget them from? Can they be cut to fit the space? Is there a certain way they are put in, attached? Any step by steps out there? I have a motor that is weak and would like to try this out and see what happens. The train is nothing special just a project that i was given for christmas. Thanks Mike
I put rare earth magnets into an old PFM brass steamer. The factory open frame motor barely had enough torque to move the locomotive and it ran very hot. The rare earth magnets solved that problem 100%, runs cool, lots of power.
I got mine mail order from All Electronics, over the 'net. Google for neodymium magnet and a bunch more vendors will show up. Radioshack sometimes has them.
They come in various sizes of square and round. I used square ones, about 7/16" if memory serves. Take your motor apart and measure the max clearance for the magnet from front to rear. You will want to stack up 3 or 4 of them to fill the space between the pole pieces. I don’t think you can cut or file them to fit, better is to cut or file the motor. You want the most magnet you can squeeze in for best strength.
Don’t leave an air gap between the pole pieces, air will weaken the magnet field. Fill in any gap with a piece of mild steel.
Direction of rotation is controled by the direction of the field. To get your locomotive to run in the same direction, install the new magnets with the north pole pointing the same way as the old magnet. You want to check magnet orientation BEFORE taking the motor apart. I used an ordinary magnetic compass to find the North pole of the old magnet and of the new magnets. I got my compass too close to the new magnets, and I am now the owner
http://www.kjmagnetics.com/magnetsummary.asp#blocks
http://www.micromark.com/super-magnets-20-pieces,9966.html
http://www.proto87.com/model-railroad-motor-upgrade.html
http://webspace.webring.com/people/ib/budb3/arts/motor/pit71nmag.html
You can’t effectively cut the magnets without a diamond saw. Filing by diamond files is also OK. note… It is the devil’s own work to remove the powder from filing or sawing should you have good diamond tools. Both the files and the saw blades are magnetized themselves in the effort, but are easily demagnetized.
I have re-magneted two old pitman open frame motors and they went fabulously. Extra torque, lower speed operation, less heat and less current. I did find one magnet size that was just about 1/32-inch shy of filling the gap and used thin sheet high permeability silicon-steel from an old audio transformer to close the gap. The gap must be fully filled with zero air space to realize the full value of modern Neodymium-Iron-Boron magnets. (currently the most powerful permanent magnets on earth.)
There are quite a range of energy product Nd:Fe:B magnets out there from the early 20 mGOe (mega -Gauss-Oersted) to the super powerful, expensive and rare 55-60 mGOe. Most stuff on the market is surplus and in the 30-40 mGOe range.
The Japanese more or less perfected these magnets and produced them in quantitiy. However the Chinese currently supply and hold the bulk of the world’s reserves of the rare earth oxides used in their manufacture and have more or less limited the raw material sales out of their country to boost their own magnetics industry. (such clever capitalists, those communists are)
Warning: The “curie point”, (temperature at which a magnet looses all its magnetic properties), is very low for Nd:Fe:B magnets and localized heating will result in localized de-magnetization or weaking of the magnet, in general. Keep 'em cool boys.
Richard
Mike.
No need to cut and shape magnets. Already suggested K&J Magnets has the sizes you need to stack up magnets to power your motor. You will not believe how strong they are and easily shatter if allowed to slam together. 1/4X1/2X1/8 and 1/32 thicknesses is the sizes you will need most. The sizes are approximate due to the nickle coatings. I bought enough to do several motors at once so shipping was reasonable. KTM motor that was done using two 1/32 and three 1/18 inch thick magnets. http://i1081.photobucket.com/albums/j348/locoi1sa/K5s%205698%20project/SAM_0503.jpg
Pete
To all Those Who Have Answered:
Do these magnets also drop the current draw of the old motors? It would see logical that they would.
I have an old brass steamer that I would like to improve performance on and then install DCC.
Am hoping that this would work as a good substitute for getting a can motor.
Thanks!
Chuck
Chuck:
Yes, they drop the current draw, often substantially.
Dave
It will also reduce the speed of the motor, but usually by just a little. I’ve gotten a number of open-frame motors running a lot better simply by changing the magnet! And unlike cheaper magnets and lesser quality alnico (high quality alnico is fine), they won’t lose their strength over time. So far, the only two ways I know of to weaken a neodymium magnet are to break it, or get it extremely hot.
Chuck.
Yes. When I tested the motor for the K5s project it drew nearly 2 amps stalled at 12 volts DC. After changing the magnets and cleaning the commutator and brushes and adding a drop of oil to the wicks on the bearings it now draws .08 amps at 12 volts and stalled at .85 amp. The big surprise you will find is the improvement in torque output at slower speeds. This loco weighs over a pound and has 6 eighty inch drivers that will slip at speed step one at under 2 scale MPH.
I had a write up about the Bowser skew wound DC71 motor using Neo magnets. I can’t find it right now but it suggested chamfering the commutator slots and reducing the spring tension on the brushes essentially turning into a super motor. This is the motor that is in my Bowser I1sa 2-10-0. It has performed great for many years using an older TCS T1 decoder that can handle up to 2 amps. After tuning the motor it will get a Loksound Select decoder and speakers.
Pete
I replaced the magnets in some DC 70 Motors in Hobbytown drives. It was easy using Neodymium magnets from K&J or from the Proto 87 website.The results were a good improvement in slow speed control a slightly higher top end speed much better overall speed control through the entire speed range. There was also a 2 to 3 tenths of an AMP decrease on current draw. I also cleaned ans lubed the commutators and bearings as the magnets were replaced
These Hobbytowns have always been good performers some are almost 40 years old long past the break in stage.The time effort and cost were worth it for the performance improvements.
Ron High
Been away from the computer for a while. Thanks everyone for all the great info. Gonna get onto the sites provided and start into this project. Might also re do the roundhouse motor as well. Mike