This is a 1/32 scale interpretation of a Terrier locomotive. It is based on the drawing of the Terrier locomotive, "Bodiam" by Leslie Darbyshire on the Colonel Stephens Society's website:
The image is used with permission.
It is relatively small loco anyway, and looks small compared to G scale (circa 1/22 ) locos etc.
I have interpreted the drawing in making the model, and have tried to make it easy to print.
I have not included details like the "proper" hook connectors on the buffers. There are some alternate bodies included with various bits of detail. Some Terriers have horizontal pipes from the tanks to the funnel box. These are difficult to print unless the whole lot is printed together, when it becomes difficult to remove support structures inside.
The "Short Frame" is NOT scale length, but has been reduced to allow the frame to print as a single part on 200mm print beds. Everything else is smaller and should also print on 200mm beds.
There have been some comments that the coal bunker is too high, and I based this model on 32646 that ran at Hayling, but there are many others that had lower bunkers, so I have added a "Low Coal" Body back to better represent these models. The main thing is to have fun!.
The design uses m3 sleeved inserts in the body parts and wheels to take 8mm long M3 hex head screws to hold the parts together. It uses two "arduino smart Car Robot Plastic Tire Wheel with DC 3-6v Gear Motor" - be careful to get the ones with twin shafts, and not the one with a shaft on only one side.
There is a slot in the body to take the slide switch on the "RC ESC 20A Brush Motor Speed Controller ". There is room for the controller, an RC rx and a 1000mAh 2S lipo in the main body. Alternatively, you can use a Wemos ESP8266 with sound card and (and the same RC motor controller) to get a DCC controlled loco with sound. (see https://github.com/dagnall53/ESPMQTTRocnetSound)
The latest version of the software now can chuff and toot at the same time: https://www.youtube.com/watch?v=Pg5r6MZDhww
There is a video of some tests of the spring concept here: https://youtu.be/I7FIhVYsUMA
The early F360 design process is shown here: https://youtu.be/74LDF40UaGs but a lot has changed between that video and the current design.
The body and frame are screwed together with M3 8mm screws and 4mm M3 sleeved insert holes,(to total 4 for the smoke box to hold it down) and the Buffers beams are screwed on using two 1.8mm by 12mm screws each.
4 more 1.8mm dia 12mm long screws hold down the cab top.
The steps need to be glued on,
M3 8mm bolts, 16 needed.
1.812mm screws, 8 needed
3mm shaft, 51mm long 1 needed
3mm7mm*3mm Ballraces, 2 needed.
Motors: 2 needed
10A RC Brushed ESC
1500mAh 2S lipo +Extension cable for LIPO charge socket (to make charging available from rear bunker)
Wemos D1 mini +
Adafruit MAX98357 I2S Class-D Mono Amp
40 mm loudspeaker
I painted my body matt black
To finish it off I added some 0.7mm brass wire handrails and some Slaters 7951L - 7mm - 12 x 3.2mm Brass Handrail Knobs.
I also printed some BR crests and numbers and pasted these on, as well as printing some coal on card to cover the electronics in the coal bunker.
WARNING: MAKE sure the screws connecting the con rod to the wheel are well "secured with Loktite screw lock (or similar) and well secured before testing the motors. IF NOT, one side WILL tighten up and lock the con rod, either breaking it, or putting the wheel sides out of alignment. I have done this too many times now and need to be more patient!
Printlarge parts using PLA, as they warped when I attempted prints in ABS.
0.2mm layers, 0.4mm nozzle.
This was designed in Fusion 360, by adding a canvas, making it the correct scale, and then building a sketch by tracing the key features.
I initially used "save history" and then played back the design sequence and video it.
Later in the project I made some big changes, (for example rotating one of the motors), and detail changes to the fixing screws etc.
My initial wheels, as in this video, needed to be redesigned as the con rod hit the frame,
The real loco has smooth sides, but I added some "side features" like a frame and welding features to add some interest. For purists there is stl without these features.