Don't use heat shrink on the

Don't use heat shrink on the spring to insulate it. It will not last very long at all and will short and blow your decoders motor circuit. Use a piece of wire insulation stripped off a wire.  Look for a better open frame motor than the one pictured. Here is one I did for my PRR K5s Pacific.

http://s1081.photobucket.com/user/locoi1sa/media/K5s%205698%20project/SAM_0511.jpg.html?sort=3&o=56

This picture is fuzzy for some odd reason.

http://s1081.photobucket.com/user/locoi1sa/media/K5s%205698%20project/SAM_0503.jpg.html?sort=3&o=63

Here is my 1950s vintage F3 2-6-0.

http://s1081.photobucket.com/user/locoi1sa/media/F3c%202-6-0/SAM_0407.jpg.html?sort=3&o=4

 I buy my magnets from K&J Magnets. Very good prices and super fast shipping.

Both of these locos have Loksound Select decoders in them and run flawlessly.

        Pete

Don't forget to shim any air gap

Filling any air gap will keep the magnetic flux from breaking out of the circuit and bypassing/reducing the field through the armature. Use mild steel or soft iron as shim material. Over tightening the motor frame back on to the magnets should be avoided as the ceramic magnets are glass-like under the nickel plating and may just crack and splinter. They cannot be filed or drilled for the same reason.

Only other thing with some

Only other thing with some open frame motors used in DCC, is the older open frame motors drew high amount of amps which can burnout a decoder.

Insulating motors

What you have to insulate is the motor frame from the locomotive frame.  On a typical open frame motor the motor frame is used to ground one brush to the engine frame.  Its that big screw sticking out of the bottom of the motor that's the problem.

I think these will be easy to isolate

The nice thing about these motors is that, while one brush is indeed connected to the frame, the only connection is through a wire brush spring.  It looks like insulating that spring would completely isolate the brush from the frame.

In contrast, I have some MDC motors where the brushes are not so easily isolated, meaning that the entire motor has to be isolated.

Bowser probably carries

Bowser probably carries replacement parts to isolate the brushes..worth it in my opinion.  Since you're removing the magnets to install new super magnets you might check the shaft play and install thrust washers (available from NWSL).  I found this did a lot to quiet down the motor.  I used a laytex caulk to mount the motor first using the regular, metal mounting screws..then I removed the metal screws once the laytex "started to set".  I then used some plastic screws as an extra precaution..probably didn't need them.  Bowser recommends putting some of their "conductalube" on the armature and running it in to remove carbon deposits that may have built up over the years.  If it is a new motor you don't have to do that.  I found that it did clean up the armature and it can "do no harm".  Lubing the armature can be done after the motor is reinstalled (or before).   

Conductalube?

Thanks for the suggestion on the thrust washers.  I'll check the shaft play and consider adding some washers.

Is Conductalube anything like No-Ox?  I've always head that you shouldn't put No-Ox on a commutator (what I assume you mean by armature, since I can't see how you'd get carbon deposits on the armature) since it can damage carbon brushes.  Is that not correct?

Ken.  I use a pencil eraser

Ken.

I use a pencil eraser to polish my commutators. Light pressure while spinning it slowly in a drill chuck will polish it in a few seconds. All the open frame motors I have super tuned draws less than 1/2 amp stalled. Super magnets, shimming, oil wicks on the bearings/bushings, and a polished commutator. The next part is next to impossible. I try to make the brush contact pressure as low as possible but without sparking. I use a 9 volt battery and power the motor and adjust the spring pressure until I see sparks from the brushes then increase it until the sparks disappear.

If you can find a Bowser DC71 skew wound motor and super tune it you will have a very high torque slow running motor that will put any hobby can motor to shame.  My Bowser 2-10-0 would pull a house down on speed step one at barely a crawl.

Pete

Super tuning

Pete,

I'd love to see some details (article, thread, something) on super tuning these motors.  Specifically:

• How much end play is acceptable/desirable?
• Thoughts on magnet size and strength needed - I've heard that too much is as bad as not enough
• How do you make the oil wicks, and where do you locate them?
• How do you adjust the brush tension?  Just bend the spring, or is there a better way?

Your method sounds like exactly the sort of thing I'm looking for.  I firmly believe that these motors can be made into good reliable runners without needing to be replaced with (expensive) can motors.

Also, in your first comment you said that heat shrink won't last long.  Not that I'm doubting what sounds like the voice of experience, but why not?  I wouldn't think there would be any appreciable wear between the spring and brush, nor would I think that heat shrink tubing and plastic wire insulation would be that different anyway.

"Tuning" doesn't sound quite right.

How about repair and/or upgrade?

I've always thought tuning meant optimizing adjustments to user adjustable parts. As in the old days of automobile carburettors and engine spark plug timing. The tuned engine is still the same set of parts and specification afterwards.

For these older style open frame motors, replacing the weak (or just  weakened by age) magnet with stronger Neodymium is definitely an upgrade. As is isolating the brushes for DCC. It's just not the same motor anymore.

Ken.  End play usually ends

Ken.

End play usually ends up at around .002 to .003 inch. I use a fiber or plastic washer for this.

Magnet size depends on the width of the steel top and bottom plates. The ones I have done have used 1/4x1/2x 1/8 inch thick. Stacked up together. Measure the old magnets height and stack up the super magnets to equal the height of the old magnet. When I order my magnets I also get some 1/4x1/2x1/32 magnets to make up the hight difference.

http://www.kjmagnetics.com/proddetail.asp?prod=B842

http://www.kjmagnetics.com/proddetail.asp?prod=B8401

Oil wicks are made from felt cloth patches. The magnets will hold it tight against the rear bearing and on the front some motors will have a slot for one. If not you can wrap a thin piece of brass wire around the top motor frame to hold a piece of felt against the bearing.

Brush tension is done by bending the springs. There are two types of springs commonly used. One is a coil spring that I remove and cut a couple of coils off and then stretch it as needed. The other is torsion type with the two legs.

Heat shrink is too thin and is not very durable. It will wear out in a very short time due to the vibrations of the brush holder. Been there done that and I speak from experience here.

Maybe I can get a few old motors together and do an article for MRH with some step by step pictures.

Pete