I've worked at trying to acquire all the models that were made of UP diesel locomotives from the end of WWII to the mid 1970's. I believe I have all the models that were ever produced. I also have some body shells that I bought on Shapeways before it went down. I'm down to about 10 engines that UP had (some only 1) that have never been commercially modeled.
I've never found a N scale RS-27 (UP had only 4) with the exception of a kit that Briggs Models put out some years back using an N scale Alco RS-11 for the running gear. They seem to have quit producing the body and I haven't seen any for sale. With that in mind I'm attempting to design (Fusion) and print a N scale RS-27 body shell and fuel tank.
(Don Strack's Vol 1 & 2 are great UP reference material)
I started by looking for a late model Atlas RS-11 to use for the running gear but couldn't fine anything under $100 used so moved on from that. One search I found said that a late model (1999 on) RS-11's wheelbase is right on and another said it is 4 scale inches too long. That one also said that the 1999 up RS-3 is 8 inches too short and others say a foot too short.
I found a nice 1999 Atlas RS-3 for $75 and bought it I'd never notice 8 inches in N scale but realize others do. So if I get the print finished and up be aware that it isn't totally correct wheelbase wise. More on this later where you will see that the body, pilot to pilot will be within inches of the correct length.
Also I don't have any detailed drawings for a RS-27 so I'm working off of pictures, taken at different angles for how things are so there will be more problems than a few inches of wheelbase. Hopefully it will turn out 'good enough for me'.
First a copy of the RS-3 frame was designed and printed using the RS-3 running gear. Then a rough body was designed and printed next. This way I can start design work for the body knowing that it will fit on the frame.
There were two....
.... major interference points that had to be dealt with. Mostly caused by the fact that the RS-27's cab was moved further forward to make room for the larger/longer diesel prime mover.
A shell of only half the body was made, which made seeing if there was other interference points easier.
The running gear was pulled apart so that the frame could be modified.
Most of the frame modification (usually referred to as 'milling' the frame) was done with a jeweler’s saw and files.
A large Bridgeport clone mill was used to mill the square box type side area off that were hitting the shell. I don't really like using the mill on these small frames. I haven't ruined one yet but the mill and 8 inch vice were meant to mill larger work. The vice doesn't have much feel for if you are using too much or too little for these fragile frames. I milled a little of one other area but then went to the saw an files. I also
use a flexible shaft Dremel type tool for this work at times.
The fit is now close enough. After the initial frame mods.....
......... a small decoder like an ESU LokPilot would probably work but I hope to use an ESU LokSound decoder with a speaker so went further in making room for that to happen.
I had to do a little 'side notching' (above) to make a channel for the ESU decoder wire to run to the top from the bottom motor cap.
This project is going to take a while as I only work on it a couple hours at a time so that I can continue with wiring and laying track on the layout. Don't want it to come to a standstill but I'm only good for 2-3 hours a day at that so will have time to continue with this project also
The menu for the Alco RS-27 build is
( HERE ) .
Sumner
