Building/upgrading a Hobbytown/Cary E6A

[Darth Santa Fe]

I now have the large 1" flywheel and one of the NWSL universals. Walthers made it look like there were enough parts for two universals, so now I have another set on order that I'm waiting for.

Anyway, here's the most recent progress.

The Maxon motor only has a 2mm shaft, and the flywheel and universals require a 2.4mm shaft (which I knew before I ordered them), so I drilled out the middle of some K&S 2.4mm brass tube to 2mm to get the flywheel and coupling onto the motor. It was kind of a trial and error process, and I never got one that was perfectly straight, so when I got close enough, I mounted the flywheel on there and drilled a couple small holes in the flywheel to get it perfectly balanced. The shaft on the upper gear was slightly too small (probably 2.38mm or so) for the universal coupling, so I squished the end of the shaft in a vise to expand it outward a little. The copper motor mount was soldered together before, but I discovered pretty quickly that solder is NOT a good mount for motors! The mount is now held together with 2 ton epoxy, so it should last forever now.

Having just one of the universals in there was enough to improve operation a LOT, so it should be perfect once I get the second one. And with that 1" flywheel on the coreless motor, this thing coasts like no other!

[Darth Santa Fe]

Although the old gear tower isn't the quietest, it's one of the most reliable there is. The standard Hobbytown drive is also one of the smoothest once fully broken-in. I've heard a number of stories on how bullet-proof (or even missile-proof) and long-lasting they are.

[NeO6874]

Impressive work Darth.  I do have one question though -- why did you use the old (?) gear tower instead of using a NWSL (or similar) replacement?   

[Darth Santa Fe]

I've been gathering the proper kits and parts for a while now to build a Santa Fe E6A diesel, and now I've finally got just about everything needed to do it. I thought I'd show some progress pictures so you can all see how it's coming along, and maybe get some ideas for your own projects.

I'm building the diesel using an older chassis from Hobbytown, and a metal body from Cary (Bowser).

This is the chassis in its original construction. You can easily see that the gearing was all outside, and it stuck out far enough that trying to cover it all up wasn't possible. So, I decided to move it.

This was probably the hardest upgrade I've ever done on anything so far. The gears had to be pulled and repositioned, and because there were no ridges on the shaft where the main drive gear went, the gear had to be soldered on. I also had to split the truck frame in two, and grind out a lot of metal for clearance. The gear tower was too low when turned around, and had to be shimmed to get the proper gear mesh.

A third screw had to be added to the bottom to hold the truck together. This needs to be done slowly and carefully, or it can fail like my first attempt. The truck holds together fine, and the gearing works just as well as before.

I replaced all the old U-shaped bearings with pieces of K&S #127 1/8" brass tube, since the old bearings allowed too much slop, and they weren't perfectly shaped so they caused excessive drag, especially with the body on (current draw with a new motor was well over half an amp at half speed). The new bearings have very little slop, and they allow everything to move extremely freely no-matter how much weight is added.

The old wheels were half brass and half plastic, and at a scale 40", they were too large for an E-unit (the front set was also binding with the main gear). I found that Intermountain 36" freight car wheels were a near-perfect fit on the old axles, and needed very little modification to work. The spacers on the backs of the wheels need to be filed down half-way or more to get them to the proper width on the Hobbytown axles, so you'll want to keep an NMRA standards gauge and wheel puller handy to make sure everything's perfect. The new wheels look much better than the old ones, and they don't bind with the main gear, so except for a loss of a little traction, that change was a win-win.

This chassis came with Hobbytown's (not Pittman's) massive DC-90 motor, which is a great motor if you've got a strong power supply, but at 0.4 amps out of the mechanism, I wanted a different motor. I replaced it with a Maxon 9-pole coreless motor, which has over 50% more power than a Mashima or Sagami, runs excellent at low speeds, and draws very little current under no load. The only problem is it's too fast for a passenger-geared E6 past 8.5 volts (the chassis has 10:1 gearing), so I need to find a way to reduce its speed.

I plan on having the headlight semi-permanently mounted in the shell, so I made some simple little plugs using K&S brass rod and tube. With the plugs, I can un-hook the lighting for easy maintanence on the mechanism. To prevent shorting, some electrical or masking tape should be used around the plugs or motor and shell.

The frame needed some grinding done around the front and back to fit the Cary body, and some grinding also had to be done to clear the repostioned gears. The body sat too low on the chassis before, and had to be raised about 1mm.

That's about all my progress so far. I plan on replacing the rubber-tube and rod universals with some good ball and socket universals from NWSL, and I'm also going to add a large 1" flywheel from NWSL. I'll be posting my progress (like painting, detailing, and upgrading) as I make it, so be sure to stay tuned.