Model Train Journal

I always have a soft spot for things orange and maroon. The big Bi-Polar is no exception - no way I would ever scratch-build one of these monsters, but MTH has been kind of giving them away. I got a complete unit from SW at a very favorable price, and I got fragments from Perry's Hobby, off the eBay, so I can leave the complete model intact while I proceed. I have complete trucks, and complete bodies laying around at the moment.

I have not been looking forward to pressing the wheels off, but this morning I made a jig, and turns out the wheels come right off! The old SD45s were a bear - took an arbor press! Not so these - they might need a special clamping fixture for machining. They slip off with just a nudge from the big drill press.

Current plan is to put tires on the Zamac wheel centers, insulated one side, and use a baggage car or something for pickup. I have done that often with 3-rail stuff - makes things easier electrically.

Two hurdles come to mind - one, I don't really know how the bodies attach to the mechanisms, although I have the intact unit to disassemble if I want, to see what kind of swivel plates go in there - and I shall need extra MTH pantographs. I will be checking with the lady at MTH parts as soon as I see daylight with this project.

I shall machine one driver right now, before I head to the ninety degree airport. Changing a carburetor there - that will take all day.

Edit: flange machines like hot butter. Tire, not so much. Doesn’t look like it, but the tire may be steel.

Bob,
Looking forward on how this project turns out. I was thinking of just reducing the tire width with my new 1927 South Bend 9 lathe on my two MTH Bipolars. My third rail would be the catenary wire.
Rob

That will work. My solution involves a bunch of 48" tires that I have hoarded over the years. I will cut the tires with a jeweler's saw, then machine the Zamac to fit. I just use paper, soaked with shaft Loctite, for insulation. After a week, the tires are welded.

Take material off the back of the wheel. I should have dimensions tomorrow.

Bob Im glued to the monitor with anticipation of the next post.

No need for dimensions. I sawed off the steel tire, machined the back of the wheel all the way to the spokes, used .035 cardboard and blue Loctite, and should have one lead truck done by mañana.

Further simplicity revealed. Cardboard as an insulator; that’s inexpensive and smart. Joe Foehrkolb used fishpaper for his insulating material. I would love to see how you set it up on the lathe to machine it back to the spokes. Still a lathe newbie here using the original south bend tool post, not a quick change tool post yet. Most of my lathe experience is from college physics lab back in the late 80s.

Sounds like an alternative to the late Joe Fohrkolb's fish paper.

Doesn't need to be exotic. Just save scraps of card stock of various thicknesses.

I am using plated brass tires I had laying around, but the better solution is to find someone with a screw machine or computer-controlled lathe and have them spin out 20 tires in free-cutting steel. You want the insulation to be around .010-.015.

For the lathe work, all you need is a semi-accurate 3-jaw. I didn't even pull out the collets.

Cut the back of each wheel until the spokes are shiny. Then carefully saw off the tire. With the wheel on its axle,cut the rest of the flange off. Don't trim the outer diameter of the wheel; it is already concentric.

Then just glue on your tire. If you want un-insulated drivers, just use brass instead of paper, but don't make the press fit too tight. I suspect these wheels are fragile. Use Loctite to secure alltires.

Bob,
Thank you for the further explanation. I also suspect the spokes are on the delicate side.
Rob

The wheels are soft Zamac, but cut quite easily. The press fit of these wheels to axles must be jealously preserved - but it is not a good enough fit to permit much machining.

I center-drilled a steel dowel, and tapped it on the lathe 10-32. I am using a 10-32 bolt and two washers to hold the wheel centers during machining. The steel tire will heat up, slip,and fall off - which is too bad, because the tires I am using require .025 or so card stock insulation.

If there were a market, we could spin up some better-fitting steel tires - not sure if this is something easily done on a computer-controlled lathe. I sure don't want to make 28 of these things by hand.

I am about to finish the first "idler" truck, and have started one of the powered trucks. Interesting project.

Bob,
Thank you for the update and less than great news about the zamac wheels. Sounds like it could be tedious with 28 wheels. Still I think this is a good endeavor, especially since the MTH Bipolar seems like a sturdier model than NJCB version.
Rob

Halfway done, if you don't count insulating the front wheelset, which is a 2-rail pair.

Each wheel seemed to be a different problem - the tires will come off during machining, which is a lot easier than sawing them off.

The geared axle should be preserved in situ, by using 1/16" steel plates under the drivers, pressing them off the axle. I used a scale and a drill gage (yes, it is spelled that way on the plate). Plenty of room under the wheel, and the steel plates just rest on the jaws of a vise.

Pretty much all that remains for this half is assembly and a track test. I will try for photos soon.

For the second "engine" (not sure what they are called on electrcs) I may trim the face of the drivers after everything is done. Actually, I may do that to this set - not that one could actually see the difference. Then I can move the sideframes inboard.

bob turner wrote:For the second "engine" (not sure what they are called on electrics)

motor

Although laymen often use the words “motor” and “engine” interchangeably, from a technical point of view, an engine uses fuel to create heat that it converts into motion, while a motor uses electricity to produce motion.

Thanks for editing that. I am putting off the drive to the airport, so inclined to type:

Faced the insulated drivers, decided that it did nothing for appearance, and left the "hot" drivers with extended faces. Machined the 2-rail wheelset to meet the track after the somewhat larger main drivers are on.

Deep dive into nomenclature. Best I can tell is the part with wheels is the "frame," and for the GG1 the engineers speak of two frames. The now official designation of the Bipolar is 1-B-D+D-B-1, where the plus sign means articulated. I would think that the 1-B portion is more of an articulated joint than the main one in the middle. I did not find any better nomenclature, so what I have pretty much finished is one out of two "frames," or a 1-B-D section.

A steam locomotive has a boiler and an engine - or in the case of an articulated, two or more engines. We call the engine part a "mechanism," or occasionally a "frame." An electric locomotive is often referred to as a "motor," although in our case here we are dealing with 12 motors.

This is just a first guess - I am wide open to any definitions you all might advance.

Isn't Summer great? Nobody is doing model trains when it is 74 degrees out and the wind is right down the runway at nine knots! See you this evening!

Changed my mind - the drivers look better when faced. I am over halfway on the remaining frame, facing all of them.

Rather than un-pressing the first frame, I am going to try some very careful disc sanding. We shall see.

The test of the first frame did not go well. I am using motors out of an MTH SD-type Diesel, and suspect the worm is bottoming out in the frame casting. I shall be tackling that this weekend.

Remaining challenge is how to bolt the bodies on. I do have SW's intact model, and can take it apart to see how the articulating jount is handled.

This week has been fun - I am in the middle of replacing a Stearman wing spar, and so far it has been successful beyond my expectations/fears.