Del Prado NS1100 nearly finished

Progress continues on my Del Prado motorization project. It's nearly finished!

Adding Weight

I was a bit worried that the poor thing, with only one motor bogie, wouldn't be able to pull much. So I decided to add some weight. First step was to make up a sacrificial master out of polystyrene. With some careful trimming and cutting, I soon had a weight that fitted nice and snugly over the gearbox and universal.

Polystyrene isn't known for its weighty properties, so I needed to convert it into something a little heavier. My old stand by, white metal, sounded like just the trick. So I made up a mold from some scraps and mixed up some clay and water to make a mold. Here is my fairly crude mold, with the sacrificial polystyrene in the middle.

I melted out the polystyrene with a blow torch, and then poured in the white metal. I could probably just pour the metal straight in, but I was worried about the polystyrene not burning out 100% cleanly and leaving some charred residue.

Here is the metal straight out of the mold:

I gave it a clean, and then attacked it with the Dremel to grind it down to shape. Finished result:

The weight difference was quite significant:

Nearly a 3x improvement in weight! And all over the motor bogie too. Fantastic.

Adding a Decoder

I knew that adding a decoder to such a small loco would be tough, especially with no space above the motor or gearbox. This only left one spot: behind the motor. Unfortunately the motor shaft stuck out a long way so I needed to deal to that as well. I used some plasticine and tape to protect the motor from any stray metal filings, and then attacked the shaft with the Dremel again.

Next I took my decoder, a Digitrax economy model, and chopped off the bulky socket.

Much smaller! I goofed up the removal and nuked one of the pads, but that is only for the rear headlight so not too much of a concern. Now I had to mount it... I used some PolyZap again and it seems to be holding quite solid.

I made up a small "multibox" PCB to keep the wiring tidy and fitted that on top of the motor:

Bogies were now fitted and the wires from each one routed to the multibox PCB. A bit more origami followed, but before long I had it all wired up:

Test run

A bit of filing for the nubs on the PCB followed, but in the end the body is a nice snug fit over the shell. I did a quick check with the multimeter for any shorts, placed it on the track, called up loco #3, and dialed up the speed. And off it went!

It's not especially quiet, and it needs couplings still, but I'm quite happy with the result. Placed next to my Kato Glacier Express loco it is clear which one has the better drive train, but for a loco that cost me no more than $10 in parts (excluding the decoder) it is very capable. I was worried about the pulling capacity of it, however it managed to push 5 loaded coal wagons, from a standstill, up a gentle incline! So don't think I need to be too worried, it will make a great wee loco for pulling around short trains.

Still a few tweaks to be made:

• Add couplings and buffers
• Add the windows back in
• Add some headlights?
• Replace the pantographs with nice Kato ones.

I may also investigate adding some capacitors to the decoder to act as an "electric flywheels", so that small breaks in conductivity don't stop the poor thing dead in its tracks.

But on the whole... very happy with it! Rachel gave it the nod of approval, saying it was "very cute". I look forward to seeing it pull its first passenger train into Raparapa in the near future.