As I have already determined that I will need to re-machine the plates, I decide to check the escapement components as well, as I don’t want to machine new plates then find problems that I could correct now. The escape wheel won’t be going anywhere, so I focus on the pallet fork and pallet bridge, I am using the pallet bridge directly from the base movement, as it is one part less that I have to machine. I thread the holes for the screws, and fit the bridge, or try to.. the holes for the screws and steady pins do not line up quite right, with some alteration I manage to get the bridge down but the pallet fork is siting at quite an angle, unable to engage with the escape wheel.. Oops.. I figure that by moving the holes for the bridge half a millimetre all will line up nicely and add it to the list of adjustments to be made.
Back to the drawing board….
Determined to get a working movement happening, I return to the computer to check what I’ve done wrong, and to also make some modifications to the design based on my initial observations.
I check the distances that I measured between wheels against those in my computer model, and also the wheel models. I can see (now that I know theres a problem) fairly fast that the wheels are not in the right spot, I adjust the model, moving the 3rd wheel 5/100 of a millimetre, and make sure that the wheel models are now overlapping (representing the teeth meshing together). All appears to be ok, I also add some thickness to the barrel bridge, corrected the placement of the balance bridge components, and adjusted the position of the pallet bridge.
At this point I also make some modifications to the milling program to use a larger milling cutter to do initial cutting (roughing out) followed by a smaller cutter for fine details, in a simulation this will reduce the machining time of the mainplate significantly (from 6 hours to 3) and reduce the chance of breaking the small milling cutter also.
Then back to the milling machine…
I re-machine a complete set of mainplate and bridges (much faster to type than to do) and begin the process of sizing all of the holes and fitting all of the jewels and steady pins again. In my haste I notice (when I go to fit the jewel) that the escape wheel jewel drops though the plate, I check my chart of jewel sizes.. and I’ve read the wrong line.. rather than machine a new plate, I quickly turn a bush to press into the plate that will then have the jewel pressed into it. All good!
I sit the wheels on to the mainplate, and this time everything already seems to be sitting much better..
I fit the train bridge, and wiggle the centre wheel with my finger… The escape wheel spins!! one part working, just a few to go…