GE's 25-ton switching locomotive is another one of those locomotives that's made in every scale except O. But now that I'm on the case, it won't be so for much longer!
I first heard about these a few months ago when my friend @RSJB18 mentioned them. The Long Island Railroad had a few of these little locomotives that they referred to as "Dinkies". There were hundreds of these Dinkies around from the 1940s through to the present, and many have survived in museum collections-- here's a website with many past and present photos. I thought I had seen one of these locomotives recently, and it turns out I had. I was at the Seashore Trolley Museum in Maine last summer and photographed their "Dinky", which happens to be a former Providence & Worcester locomotive from my neck of the woods.
Once I knew what I wanted to make, I had to find a suitable donor frame-- in this case, a K-Line Plymouth. Just about everyone has one or two of these around their layout (or maybe more if you're @gunrunnerjohn).
After dismantling the Plymouth,I was left with a big pile of parts. I want to reuse as many of these as possible in the 25-tonner kit. The motor frame, reversing unit / interior insert and the couplers seemed most reusable. The smoke unit would be a challenge since it's such a snug fit into the Plymouth and the Dinky is even shorter.
I started the digital design by making scale drawings of the two most critical parts-- the motor truck and the reversing board.
Working around the drivetrain, I produced a new body and frame, including the screw hole pattern for both the original 3-rail couplers so they can be inserted into the pilot. I had to widen the frame to squeeze everything in, but the overall length is very close to 1:48th scale.
The first prototype came out pretty good in both materials. I can 3D print with two different methods and for this project I am advantageously using both-- the UV-cured resin for a highly detailed body and the ABS filament for a sturdy, durable frame. I was able to do a test build with a little bit of filing and snipping.
The couplers were just the right height and the electronics fit snugly inside. Perhaps the original smoke unit could be incorporated, although it would need to be carefully modified to neck it down to fit the 25-tonner's narrow little stack. I'd rather leave space for a command control board in my personal build, so I'll leave the smoke unit out.
Here's a video of the prototype running on my layout.
The second version of the kit fits beautifully, so this weekend it's going into my workshop for paint while I start on forming the grabirons from wire. Stay tuned for updates!
