Using an N Scale Spectrum Mechanism To Make A Heavy Consolidation
A good place to start is to read Michael Wongís excellent article about disassembling the Spectrum N scale 2-8-0 so as to install a TCS decoder. I donít use DCC but Michaelís procedure for taking apart the locomotive is excellent. This is the URL for his article:
I removed the body shell, pilot truck and pilot following Michaelís instructions. I found that it is important to reinsert the screw holding the cylinders to the frame so that the valve gear is kept intact and in place.
My next concern was to remove the metal hemispherical piece over the light board. Remove the plastic clip holding the light board and motor leads into two metal tabs cast into the frame halves. Then remove the silver weight that sits over the light board wires. Carefully separate the motor lead wires and the light board wires from the two metal tabs and fold them aside. They are only held there by a friction fit and are easy to separate. Remove the light board by pulling back on its wires. Remove the black plastic piece below them as well. It is very important to leave the motor leads intact and bent out of the way. (Well, I cut all of them off on my first attempt and ruined a perfectly fine locomotive.) Clip off the two molded metal tab that once held the wires in place on each frame half. I used Tamiya narrow masking tape to cover over the gap between the two frame halves so that metal filings wouldnít get into the gears and motor. I then held the whole mechanism face down on a wood block so that it rested on its metal front end and used an Xacto #15 saw blade to cut through the bottom of the hemispherical piece that covered where the light board had been. This took only about 5 minutes to my surprise.
I now had to find a way to getting current to the motor. Looking at the area where the light board once were, I saw that it is well below the top of the frame so I decided to use it as the area for mounting my electrical contact points. I drilled and tapped a hole for a 00-90 screw in each frame half. I then made two thin strips from .003 shim brass for the contact points. I drilled a #55 clearance hole at one end of each strip and filed a small V notch at the other for the motor lead wire. I then bent each strip up at a 90 degree angle and screwed each one into the frame half after which I soldered the gray lead to the left half and the red to the right half. I could have tried placing the motor lead wire ends under each screw but didnít think there was enough slack in the wires.
Here is the final mechanism with the metal piece over the light board removed and contact tabs in place
I attached the Spectrum tender to the mechanism, placed everything on my test track and held my breath. The locomotive ran as smoothly and quietly as it did originally.
The rest of my conversion is basically cosmetic. It takes some scrapping along the inside edge of the boiler and the smoke box with an Xacto knife to get it to sit down over the Spectrum mechanism. The cabís inside width is fine. I also filed down the two nubbins on the rear of mechanism so that it was easier to slip the mechanism into the boiler yet tight enough of a friction fit so I wouldnít have to figure out a way to mechanically attach the boiler shell to the mechanism
After several test runs, I was concerned that the original cast on air pump might hit the eccentric crank and that the small rectangular appliance cast in front of the air tank on the firemanís side would interfere with the valve gear motion. I removed both and smoothed out the area where they had been. I also cut off and smoothed off the walkway above the area where the original air pump had been. I tried attaching a Precision Scale air pump but it was too bulky so I used the air pump from the boiler shell from the Spectrum 2-8-0 that I had ruined. I then used Evergreen strip stock to build a walkway up and over the new air pump which I had mounted a little higher than the original for clearance. A piece of Evergreen square stock was used to replace the appliance in front of the air tank.
The pilot deck was next on my list. I removed the original coupler and filed out the opening in the pilot so I could insert a Micro-trains 905 Z scale coupler and coupler box. This area is so fragile that I decided that Iíd go with a friction fit for the coupler box.
The pilot steps and the walkways on the boiler shell lined up very well so I decided to cut off only the top platform on the Spectrumís pilot steps and cut the original walkways on the boiler shell back a little. The auxiliary steam dome on the original shell was the last item I worked on. This auxiliary dome was used for the mounting screw on the original boiler. I filled the hole in the dome with two pieces of .010 that I punched out with my Waldron punch. I glued these so that they about a 1/16th of an inch below the top rim.
Most of the work was done. I stripped the original paint off using Scalecoat II Wash Away and then sprayed the shell with Tamiya flat black. I added small rectangles of acetate for the cab windows after I added the road number. Next I drilled 3 #77 holes in the auxiliary steam dome for small pieces of .015 wire to represent the pop valves and whistle. I left the cast on bell on the boiler front although it appears that the Boston & Albany often mounted the bell high up on the boiler behind the Elesco feedwater heater. Everything fit well and the steam pipes from the cylinders lined up with the stack. The only thing left was the headlight and I found that the #27 MV lens perfectly fit the headlight casting. I attached the lens using Microscaleís Kristal Klear.
The locomotive now runs as smoothly and quietly with its Spectrum mechanism and distinctive boiler shell.