Smokebox front

622’s smokebox front is another 3D-printed part. Like the domes and stack, it fit astonishingly well into the boiler. It was actually a nice press-fit. Interestingly, either the boiler jacket is slightly thicker than .020″ (would that happen as it curled?) or there is some inaccuracy in the 3D print. In either case, the smokebox […]

622 gets a stack and domes

That big package from Shapeways contained domes, and I’m impressed enough by the quality of the print, that I don’t think I can improve on them. A coat of primer will tell for certain, but if any sanding is required, it is minimal. Astonishingly, they fit onto the boiler perfectly! I’m still trying to move […]

Boiler saddle

When I mated the boiler and the etched frame for the first time, they produced a dead short. Somehow, I had reversed the framigami pattern so the left side ended up on the top rather than on the bottom as planned. Fortunately I noticed before bringing any destructive electrons to the party. The situation remained […]

Boiler wrapped

I designed the boiler weight undersized to allow for the tolerance of Shapeways stainless steel printing. As with my own girth, I figured it would be easier to shim than to trim the weight. However, even with the additional tolerance, while the barrel allows for slightly more than a .020″ styrene wrapper, the wagon top […]

Styrene tubes for 622’s boiler

One of the supposed benefits of writing and blogging about my projects is that I can go back and repeat a technique that was successful, and sometimes avoid the ones that weren’t. Unfortunately, when it comes to how to roll the plastic sheathing for the boiler, the book on #10 is like a nude by […]

Retreat to known ground

I’ve put the debacle of the micro connectors and missed resistor behind me, and as I said, I’ve decided to revert to connectors I know and trust. These are harvested from an IC socket, and are quite robust, but also big. Okay, big is relative in our world: I often tell people that a lot […]

A bad week for electronics

You’d think that if your father had a doctorate in electrical engineering, at least a little wizardry might have rubbed off! Nope, he kept it all to himself, apparently. The story starts with the Hall effect sensor, which the ESU decoder wants to synchronize the exhaust sound. Countless YouTube videos make this gizmo look trivial, […]

622’s tender cable

I struggled a little bit with whether to simply extend the leads from the tender-mounted decoder so that they could connect with the locomotive, or whether to create a cable with connectors on both ends. In the end, I decided on a cable, rather than having to deal with an obscene length of wires hanging […]

Tender coupling

622’s tender coupling is a sandwich of phosphor bronze and styrene. The two layers of bronze carry track power from the two sides of the engine to the two sides of the tender through a mind-bending arrangement of layers and folds. Seriously, it is such a puzzle that I wasn’t certain I would have the […]

Tender coupling tests

I recall a story about a cab ride where the engine backed around a tight corner, and the writer had act quickly to avoid losing their thumb between the cab and the tender. Photos of 622 and her sisters confirm the tender should be startlingly close to the cab. However, it would be a bit […]