3D Resin Printing 00 Model Trains #10

Abandoning an outer hub for an inner brace... was a bad idea

The Idea

I want to show off my prior wheel designs, which requires a custom chassis. Carriages and rolling stock I’ve seen all block a large chunk of the wheels. Compound this with an overhang, the wheels being slightly under the main body, then complex wheel designs become pointless. They’re barely visible.

What if the load were shifted from the outer hub to loose inner clamps?

The above is my prototype chassis. Don’t real too much in to the styling, I threw any old thing together for a quick print. Although I am curious as to how well the rods will link together. They have no braces or overlaps, they’re merely touching.

My clamp design is meant to sit between the wheels and be the length of a regular axle. Wheel to wheel. Almost. There will be a slight gap where the chassis can slide between wheels. so long as the clamps only rub a small part of the inner hub and not the main wheel, everything should roll freely.

Friction will be increased but does it matter on something so small? The clamps wouldn’t be circular like the axle, they would be sort of oval; wider in the middle to not grip the axle too tight and open at the bottom to snap the axle in. probably snapping the resin print knowing my luck!

I believe the key is to keep the clamps as small as possible, yet wide enough to not snap and only make a small amount of contact with the axle. Hopefully that doesn’t create instabilities or slipping wheels?

Real world trains connect between the wheel on the inner axle, unlike models. But real trains are far heavier, use gears and differentials. I don’t really want to do all that for the sake of seeing my custom wheels spin around.

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The Outcome

Fail. Sort of. Everything is a learning experience. Nothing is ever a failure. It’s gaining knowledge on the wrong way.

I don’t mean the broken model. That was because I didn’t use a raft, which is moronic on something so small, this made it snap when pulled off the build plate.

Nor do I mean the pipe design, which came out better than I expected. It’s strong and sturdy even without additional bracing. I would add welds to them for a final design, for polishing and realism, but it’s not a priority for prototyping.

My problem is with the clamps. They are very flimsy, to the point which one broke off. This means it can’t be used to test friction. I’m very concerned that the axle may not rotate due to the contact and just drag along the track.

While my clamps do weakly grab axles, they need to be fractionally deeper and I would say at least 0.5 mm wider. This will make them grip better and there’s less chance of snapping.

I’ll give this one more try before abandoning it for a more traditional outer axle grip… next time.

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