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In response to our nomination of Tamiya for the Makey Awards, Chip Rosenblum wrote in with this story of how he turned the Tamiya Solar Car kit into a train engine. -Gareth

I was taken by your Tamiya nomination for The Makeys, as I had a ball making something quite different from one of their kits. I was driving to a hobby shop (no surprise there!) at lunch one day. When I pulled into the parking lot of the strip mall, I saw what looked to be an electric bug making large and speedy circles on the asphalt.

The staff of the hobby shop and some onlookers were outside, smiling from ear to ear, watching this thing go. I asked what it was and was told it was a Tamiya solar car kit. The front wheels could be set at an angle so it would traverse whatever diameter one would like, and the solar panel generated sufficient energy to run the motor and gearing.

As I shopped in the store, I couldn’t get my mind away from the possibility that this kit could me turned to be a train. Long tunnels or a wooded track were not going to be a good place to try this out, but a sunny track would be delightful.

My first task was to ask the attendant if I could open the box to check the wheelbase and axle length. Pulling out my trusty tape measure, I found that, yes, this could be assembled without the automobile wheels and could have railroad wheels pressed on (after a short encounter with a drill press (with the correct back-to-back spacing for G gauge track).

I purchased the kit and headed home, and into the great unknown of how I was going to create a solar-powered railroad locomotive.

When I unboxed it, I noticed that the essence of the structure was a long plastic T-beam, running fore to aft, that supported all of the other parts. They had also provided the engineering of the solar panel and a compatible motor. I had to re-route the wires and insert an on-off switch between the panel and the motor, but that was all the adjustments that wre needed there.

I obviously had no need of the car body, so I took a look first at axle diameters. It was then time to rummage through my parts box to come up with some railroad wheels that had been taken off other train cars. I drilled them out for a snug press fit to the front axle, and gauged them. I left the screw holding the front axle loose so that it could turn from straight to curved sections. I also added the decorative bead and brass compression fitting to the axle outboard of the wheel on each side to both “decorate” that part and compensate for the fact that the gauge of the railroad wheels was less than the original width of the footprint of the car tires. If I had this part to do over, I would have made a small 4-wheel pilot truck that would have rotated more freely. When running the solar engine as it is now, it does not like to turn on short radii.

The next problem was the geartrain. When I first spied this speedy little thing in the parking lot, it was apparent that a reduction in gear ratios was necessary. When I looked at the motor/gear/rear wheel assembly, the tires were placed over the large gears with the “flange” forming what could pass for a hubcap and the cast in gear teeth facing inward. The gear train from the motor was on a separate shaft. I pulled off all of the gears, including the drive wheels. Removing the rubber tires and reversing the drive wheel gears resulted in an acceptable facsimile of a flanged railroad wheel. I added the brass swimming pool clothes check tag as prototypical adornment… By re-arranging the gears on the motor shaft I was able to have the smallest gear drive the wheel, slowing down the train and increasing torque. The other gears were left on the shaft with a clock gear added just for appearance. The difference in diameter between the rear geared drive wheel and the front railroad wheels accounts for the “raked” look of implied speed, even standing still!

I then took it out to the track for a first attempted run. Amazingly, run it did, and so I could proceed to “decorate” the little beast in appropriate and highly prototypical fashion!

My next decision was how I wanted to build the chassis that would form the structure of the train. I had some brass rail and other brass parts around, so I decided to start with that. I cut the rail and soldered it together to form the sides, back, and crossmembers. The front section is two large brass bracelet pieces from a garage sale. I was able to attach this to the plastic T-beam so that I had a stable platform for the final (and yet to be determined) additions to complete the image.

I had some cutoffs of exotic woods and inlays left from other projects, and so decided to create the “deck” and “cab” areas using those materials. At this point I had a “finished” model, but to my eyes it very much needed to be overdone. So back to the parts area I went for some high caliber parts and pieces shopping.

First I found some brass bracelet chain, gold-plated electronics whatevers with needle tips, and some shaped brass washers that the opposite ends of the electronic pieces fit in. I laid out the spacing and created the chain railings at the back by gluing down the washers, needle tips and then cutting and gluing the bracelet chain on top. In the front the bottom of the needle tips fit into the bracelet link holes, making both the decision of where they should go and the assembly of this part easier.

Other unidentified flying brass parts and clock gears made up the leading decoration of the solar panel, the imitation tanks, the drivers seat, the Johnson bar, the whistle, and with the addition of a number dial from an old adding machine the whatsit’s on the deck.

Next came the driver and his dog, or the dog and his pet driver, I’m never sure which. But something just seemed incomplete. Then it struck me, mostly because I was attending a dollhouse and miniature show with my wife Gail. The fencing. I brought it home, cut and bent it into shape, spray painted it, and then glued it into position. Now it seemed to have enough “stuff” to satisfy me, and looked just like the prototype! It runs well and brings smiles to all on a sunny day.

Gareth Branwyn

Gareth Branwyn is a freelancer writer and the former Editorial Director of Maker Media. He is the author or editor of a dozen books on technology, DIY, and geek culture, including the first book about the web (Mosaic Quick Tour) and the Absolute Beginner’s Guide to Building Robots. He is currently working on a best-of collection of his writing, called Borg Like Me.


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