Ouray No. 100
Nine axles, and every one of them turns.
Silverton Railroad No. 100 at 1:87, printed as 30 separate parts. A 2-8-0 is a count of wheels — a small pair leading, the driven set under the boiler, nothing trailing behind. Here the count is also a part list: 18 wheels on 9 wheelsets, and not one of them printed as part of the frame.
- Overall 6.9 × 1.3 × 1.9 in
- Weight 2.1 oz
- Printed parts 30
Two units, 30 parts
The locomotive and its tender, coupled, standing on all 9 wheelsets. Every part in view was printed on its own and put together afterwards.
2-8-0
A small leading wheelset, then the row of large drivers, then nothing behind — that is what the notation counts, and it counts the locomotive alone. All 5 sit in open journals cut into the frame, closed in from below by one long keeper; 4 more ride under the tender.
Hook and bar
The tender carries a 2.0 mm bar across its front and the locomotive's frame ends in a slot 2.4 mm wide. Lift the rear of the locomotive 4.5 mm and the bar drops out of the slot; set it down and it is coupled again.
16 and 14
16 parts make the locomotive: frame, axle keepers, wheelsets, pilot truck and pivot pin, boiler, dome cluster, stack, cab, headlamp, pilot beam. The other 14 are the tender, its trucks and the coupling bars.
Push it and it keeps rolling
A driving wheel is 10.5 mm across. One full turn of it carries the locomotive 1.3 in across the desk, and the tender's smaller wheels turn 1.4 times to cover the same ground.
Where it stopped
6.9 in of locomotive and tender, 2.1 oz of it, 18 wheels on the desk, and nothing holding the two units together but a bar sitting in a hook.
The wheel arrangement is the part list
9 of the 30 parts are wheelsets, and a wheelset here is not a detail pressed into the side of a frame. It is two wheels on a 3.0 mm axle. Each one seats up into a journal 3.4 mm across and is closed in by a keeper laid along the underside of the frame, so the fit is 0.2 mm all round — the difference between a wheel that turns and a wheel that binds.
The drivers are 10.5 mm across, the leading wheelset 7.0 mm and the tender's wheels 7.6 mm: different diameters, one axle size, one clearance.
How the tender stays on
No magnet, no clip, nothing to lose. A 2.0 mm bar runs across the front of the tender, turned corner-up so its underside is two faces at a printable angle rather than one flat overhang, with a collar at each end. The locomotive's frame ends in a fork with an arched slot 2.4 mm wide, and the bar sits up inside the arch. The tender swings on that bar, which is why it follows the locomotive round a turn instead of fighting it.
To take the two apart, lift the rear of the locomotive 4.5 mm — the distance from the underside of the frame to the top of the bar — and roll the tender back.
Both frames are drawn from the model's own geometry. Everything except the locomotive frame and the tender's bar is hidden here, including the bar's near collar, which from any real angle covers the slot.
Colour is a part, not a coat
Nothing on this model is painted. The red is a red part, the black is a black part, and the brass of the dome cluster and the headlamp is a third filament. The colour changes where the part changes, which is why the seam between the cab and the boiler is also a colour edge.
The ribbing along the boiler and the rings stacked up the domes are layer lines, at a size where they read as turning marks on a metal casting.
Guide it by hand across a flat desk
6.9 × 1.3 × 1.9 in overall and 2.1 oz on the scale — a desk object at rest, and a push toy the moment a hand finds it. Set both units down, line the tender's bar up under the locomotive's hook, lower the hook onto the bar, and push the bodies.
Hold it by the locomotive's body and the tender's tank. The stack, the headlamp, the raised lettering and the coupling bar are the fine parts on this model, and none of them is a handle.
The numbers
Two tables, because there are two kinds of number here: the ones you hold a tape to, and the ones the machine that made it works to.
| Overall | 6.9 × 1.3 × 1.9 in |
|---|---|
| Locomotive, pilot to hook | 4.9 in |
| Tender | 2.2 in |
| Weight | 2.1 oz |
| Scale | 1:87 |
| Printed parts | 30 |
| Locomotive / tender | 16 / 14 |
| Wheelsets | 9 |
| Wheels | 18 |
| Print time | 5.5 h |
| Driving wheel | 10.5 mm |
|---|---|
| Tender wheel | 7.6 mm |
| Leading wheel | 7.0 mm |
| Axle | 3.0 mm |
| Journal | 3.4 mm |
| Running clearance | 0.2 mm |
| Coupling slot | 2.4 mm |
| Coupling bar | 2.0 mm |
| Lift to uncouple | 4.5 mm |