The recharging method from eHow would be useless for old open frame motors, because the magnetic circuit – consisting of an alnico magnet, the pole pieces, and the armature – is capable of holding more of a magnetic charge than the magnet alone, which is why manufacturers magnetized the assembled motor, and why these motors lose a major portion of their power when disassembled. I have a copy of a 1972 MR article on how to build a re-magnetizer from the filter chokes in an old CRT TV, but neodymiums have made that unnecessary, unless you want to keep a vintage piece original.
The rare earth magnets I put into the Mantua PM-1 motor in the picture above are a big improvement, but the motor speed still isn’t as consistent as a decent can motor.
I suppose every motor is different. My Mantua motor was improved quite a bit over what it was, and runs nearly as well as a quality can motor. When the old magnets do lose their charge, a new magnet is certainly cheaper than a new motor.
Oh, that’s easy. Just keep your eye out for Penguins… if you spot 'em, you’re at the South Pole. If, on the other hand, you find yourself being eaten by a Polar bear, you know you’ve located the North Pole.
John
(And if you’re surrounded by Eskimos raising their fists and chanting… ask 'em how was I supposed to know those weren’t really lemon-flavored snow cones…??? )
Neo magnets have been used in slot cars for a while. What a great idea. I’ll try on my Rivarossi Big Six. One thing, if you put them too close to the armature, they will probably use more amps. As I recall if you increase the airgap to a point, they will run faster.
Actually I used a good quality bar magnet that was marked N and S on the respective poles. I then labeled the poles of the motor and the poles of the new NEO magnets to make installation easy, no guessing.
I did not think much about the air gap. I will have to experiment a bit with increasing the air gap to see if that creates an improvement. I probably have the magnets to close to the armature. Original Mantua motors had a good sized air gap between the magnet and the armature.
If that works better I will try to take some picks to post.
Been working more on new magnets. I’ve done a few since my last update, but I’ll just give one tonight.
The conversion is a Mantua MU-1 power truck, used in the metal Shark Nose and Talgo locomotive. A new magnet is practically a requirement to make it run well, since the old magnet is very weak and can barely move a load. The steel truck mounting plate used in the earlier metal Sharks makes the conversion more difficult, but it should be just like an MU-2 power truck for the rest. Due to a smaller amount of room for a larger magnet, I used a stack of four 3/8"x3/8"x1/8" magnets (could’ve used 1/4" thick magnets, but I didn’t see them when I ordered). I suppose if some filing is done, a 1/2" cube could still fit. Because the magnet plates are held in place by a screw alone on these trucks, they should be glued in place with the new magnet.
And there’s why it’s more difficult to replace the magnet in the older Sharks. The magnet is strongly attracted to the steel plate, and even a large amount of weight can’t hold it to the track properly. Now here’s the fix:
I glued a hefty spring to the top of the magnets, and glued a piece of thick paper to the top of the spring for insulation. The spring effectively holds the truck right where it’s supposed to be, and still allows free rotation. More than a quarter pound of lead over the truck helps too (I have an early model with no extra weight cast over the power truck).
This is an amazing post. For now, none of the information applies to my modeling but the knowledge and experience that you demonstrate are what I think great model railroading is all about.[bow]
IIRC, when the Hustler first came out, MR clocked one at a top speed of 429 smph. [:D]
Good info there on the neodymium magnets. I did a conversion like that on an old Athearn metal RDC which was running slowly, drawing about 3 amps, and generally not doing well at all. The motor had a vertical armature, which drove a gear train in the single power truck. Two 1/2 x 1/4 x 1/8" neodymiums replaced the original Alnico magnet, and it runs great now. Low current draw, consistent speed range, very reasonable perfomance for a 55-60 year old model.
The PM-1 should have had a stronger motor given the size of the magnet and pole pieces, but I guess they didn’t give them much of a charge. The large open frame motor in their steamers at the same time had a lot of torque.
I wonder if we’re ever going to see can motors with neodymium magnets used in modern locos. They would allow for more torque in a smaller package, and are already in Slot and RC cars.
I know this is an old (2008) post. But my question is; can you remove the old magnet without disassembling the motor (and risking dealing with the bbs)? You imply as much by saying " I would recommend putting the magnet in after you’ve re-assembled the motor, since the BBs are slightly magnetic".
In any event…I note that 1mm bbs are available on the internet with either magnetic (steel) or non-magnetic (Tungsten Carbide) versions for fairly cheap.
The motor’s assembled pretty tight. You might be able to get the original magnet out without disassembling, but it was almost easier to deal with the ball bearings. Assembling the motor without the magnet and putting it in last allowed me to get the BBs in place a lot easier, and then I could slip the magnet in.
Over the past few years I have upgraded about 25 Hobbytown drive flywheel drive chassis with DC70 motors using the neodymium magnets from K&J. This is a very easy improvement that is worth time and money. It takes about 1/2 hour of time and about 2.00 for the magnets. The result is about 2 tenths of an amp drop in current from 6 tenths down to 4 tenths on average. I get more power, extremely good slow speed and much better speed control over the entire speed range.I used a stack of 1/2x1/4x1/8 magnets. If there is an air gap I have read that it is best to fill it .I use old xacto blades. break them with pliers and use the end that mounts in the handle. If you place the stack in and the motor runs in the wrong direction just flip the stack over to make it right. I started with the N42 magnets and then tried N52 I am not sure if I have noticed any apparent difference. I also did a couple of the smaller DC60? motors on the Hobbytown switcher drives and feel there are similar performance improvements. Of course the Hobbytown are outstanding drives and these improvements make them better.
I have a few more DC70 powered drives to do . I also have a couple of older nonflywheel drive Hobbytowns to do at some point,it will be interesting to see how these conversions do.
