We’re still putting some effort into the escapement, but not ready to try and make it yet. In the mean time the project hasn’t stalled – we now have two shiny new fly arbour lantern pinions.
These have been made the same way as the originals, with a push fit end “washer” (rather than the soldered end cap of our first attempt for the lantern pinion on the escapement arbour). According to the engineer at Smith’s these pinions should have 10 pins, that was very helpful information. We also know the positions of the arbours (relative to the wheels they engage with) because the front support posts were intact. With this info it was possible to work out the rest of the details.
The pinions for the striking and chiming trains are the same, except that the boss at the pillar end on the chiming train needs to be slimmer (the wheel it engages with is closer to the arbour support pillar).
The construction is basically one solid piece of brass. Both sets of trundle holes are drilled from the same end, so the holes are right through at one end and blind ended at the other. A tight fitting brass washer can be pushed on to the boss at the open end and the other end doesn’t need anything. The trundles are still over length to make it easier to pull them out, which will be necessary when the pinion is attached to the arbour (pinned through the centre).
The pinion has been modeled in SolidWorks – see the image below and the technical drawing (fly_arbour_lantern_pinion_drawing.pdf). I don’t know if I’ll do this for all the components we make, it would be nice to do but possibly too much effort.
Next job is to make the bushes to go in the rebuilt arbour supports, ream out perfectly aligned holes and then make the fly arbours.