Super Magnets

[spike64]

Not exactly sure if this request is in the right section, but  anyway. How can I get a detailed 'how to' on installing super magnets in an open frame motor.  I have a United

P F M  Climax that draws well over 1 amp  when running. It is 60's technology so a little upgrading would not hurt.

[narrow gauge nuclear]

All the old Uniteds and others of that period used a pitman motor for the most part.

A single screw, (rarely two), hold the magnet to, and clamp the motor's open frame architecture.  removing this screw will allow the magnet to be removed. (Warning! the frame at this time can come completely apart in some cases.)  Thus, it is advisable to hold off this action until you have your stack of replacement super magnets ready to drop in.  The new super magnets are so powerful that replacement of the screw is not often necessary, but most put it back in or use epoxy to secure the arrangement.

Finding an exact stack that fits flawlessly is nearly impossible, but you can come very close.  If short by a tiny amount, then a thin sheet of iron or steel will close the gap. (must be of a highly permeable magnetic material).  If only slightly oversized then as long as the motor armature gap is not opened further to a significant degree, you can go with that, as is.

I have found a stack that is just a hair smaller with a thin sliver of iron or steel sheet is best.

The whole effort is not complex or tricky.  You just need to measure your magnet's height and try to purchase neodymium-iron-boron magnets of a size so that 3 or 4 stack to your height needed.  Note that any magnets of an energy product equal to or greater than 28 mGoe (mega gauss-oersted) are fine.  Some magnet sales sites don't know or offer this data, so try and find out.

Depending on how much you love your loco, a modern can motor might still be a better choice, though more expensive.

Richard

 

[Redvdub1]

FYI:  Micromark advertises super-magnets item #84991 pkg. of 20.  at 1/8" thick so that they will fit the popular Pitman DC-60 and Mantua/Tyco open-frame model locomotive exactly. 

[gregc]

http://www.proto87.com/model-railroad-motor-upgrade.html

http://webspace.webring.com/people/ib/budb3/arts/motor/pit71nmag.html

here's a link to the micromark page: http://www.micromark.com/super-magnets-20-pieces,9966.html

and here's an old thread:  http://cs.trains.com/mrr/f/88/t/120264.aspx

good luck

[locoi1sa]

Spike.

 I buy mine from K&J magnets. Most motors will take 3 or 4 of the item #B842 and maybe a couple of the B8401 that is 1/32 thick. http://www.kjmagnetics.com/products.asp?cat=11  Some will say you have to observe north and south polarity but I  have found that the motor will spin either way just as good. K&J are great people and will ship same day through the mail so no fancy freight charges and hazmat regulations are necessary.

       Pete

[spike64]

Fellow Railroaders, thank you so much for sharing your tips and part sources.  I have the magnets from Micro-Marc.  After reading the replies I'm a lot less concerned about the magnets polarity.  So now it's a matter of sitting down and getting to it.  Thanks everyone.                                                                                                                                              

Russ

[Ron High]

I used some of the Proto 87  kits, they came as a stack and also had a thin steel shim. I also used similar size magnets from K&J . Just order a couple of the thinnest ones in case there is a gap,from what I understand you do not want a gap between the magnet stack and the pole pieces. I did my conversions on Hobbytown drives with DC 70 motors.  Great improvement on real slow speed, a slight increase in top speed, better overall speed control and 2 to 3 tenths of an amp drop in current.. Of course the Hobbytown Flywheel drives were at one time considered the tops in drives,as far as I am concerned they still are. They are now even better with the magnet changeout.

Ron High

[FRRYKid]

I have a balky little engine (it barely puts one of my 62' woodchip cars.) and I was wondering if putting stronger magnets would improve the power that the engine produces. (I would like it to be able to pull two of them.) Am I correct that putting new, stronger magnets will improve the amount of drawbar pull? Thank you for your assistance with my inquiry.

[cacole]

The super magnets will improve the running quality and torque of the motor.  If your loco wheels don't slip trying to pull more cars, then the loco should be able to do so.

Something else that should be done to the motor besides just putting in the magnets is to clean the commutator, and make sure the brushes are not worn out.

[FRRYKid]

The type of motor I have is a form of a can motor. I took apart a motor of the same type that the engine uses that wasn't used to see what the magnets looked like and how to change them. The worm gear is placed directly on the motor shaft which drives a gear which is centered on the drive wheels. The other set is effectively an idler, but they do provide power feeds. With that setup, while the loco spins now, would the extra torque to the motor improve the pull of the engine?

[fwright]

FRRYKid

The type of motor I have is a form of a can motor. I took apart a motor of the same type that the engine uses that wasn't used to see what the magnets looked like and how to change them...

The magnets inside a can motor are rather difficult to replace, as they are not normally a rectangular box shape like most open frame motors use.  You have to have the right curvature, thickness, and length magnets to fit the "can" and armature.  Most can motors, being of more recent manufacture, have better quality ceramic (a few have rare earth magnets, but these tend to be spendy) magnets instead of the Alinco magnets in the open frame motors.  However, most can motors are effectively throw-away devices for lack of parts - even simple things like brushes are difficult to find.

The test for sufficient torque vs pulling power is very simple.  If the motor stalls (stop turning the wheels) with a given load, more motor torque will help. 

OTOH, it the drive wheels are spinning in place, more torque will not help.  This is the normal case with HO and smaller scale locomotives.  The spinning of the wheels protects the motor against burning out during a stall.  There is sufficient torque to spin the wheels, but not enough "grip" on the rail for the engine to pull the load.  In this case, additional weight in the locomotive, centering the weight over the drive wheels, or addition of traction tires or Bullfrog Snot can increase the load being pulled.  Changing to a motor with more torque will not change the pull unless the motor weighs more when the drive wheels spin.

my thoughts, your choices

Fred W

[Train Modeler]

NWSL likely makes a nice replacement motor, which might be better in the long run.

Richard

[FRRYKid]

I think I found a motor that will fit the bill. It is the NWSL Can Motor 22x31mm. (My original motor is 24 mm diameter x 31mm long from point to pont. However, the shafts on the ends are too long for my application. My question is this: How hard (or easy) is it to cut the shafts on an NWSL motor?

[hon30critter]

Frrykid:

The shafts are easily cut if you have a dremel tool with a cutting disc designed for metal. If you can run the motor while cutting the shaft you can get a very smooth cut.

If there are any places where cuttings can get into the motor those should be masked off.

Dave

[gregc]

when selecting replacement magnets, is it better that they are smaller or larger than the original, that is, not extend beyond the iron of the motor?