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 front required a very fine amount of filling to match the boiler jacket. As with the domes, I used spot glaze putty, reinforced with CA to build up the edge.
Along the way, I also walked around the boiler and marked all the holes that need to be level with one another, like the handrails. With that done, I could add supports underneath the running boards, pinning the front ones to the boiler. Then I took the jeweller’s saw and freed the running boards from the vestigial piece of fret that wrapped around the front of the boiler to keep the two boards level with one another.