Hi Chris/ other thread followers,
Ok, let me answer a few questions and explain the background for some decisions. When I first built the pendulum back in ’23 I didn’t have that single sheet document of Bernie’s, so I had to scale everything from the photograph below. I knew the Invar rods were 1/4″, so worked from there. The slots in the side arms have to be wider than the pallets to allow for the adjustment. The odds of cutting it right the first time are very low.

The jig I built with the XY micrometers was not really for the initial setup, but were for adjusting the pallets in as controlled a manner as possible. Not having Bernie’s golden screwdriver or intuition, there needed to be a way to capture the existing position of the pallet tip, and move it a known quantity. The secret sauce of his design was the subtle tuning of recoil, and this gave a way to start knowing what changes were made, for better or worse.
The two brass rods protruding through the centre hole are each on a separate XY stage. Each rod has a small vee machined down the side, which the pallet tip fits into. The rods have a generous hole through them so they can float a mm or so to snug against the tip. The brass segment plates let you record the pallet angle, with the small holes at 0.5 degree increments for reference. The tips of said plates also rest in the same vee as the pallets. So, the pendulum frame is locked in place with the Al plates at the bottom, and the pallet positions “recorded”. The pallet clamp plate can then be loosened, the X,Y or angle changed and then it’s re-tightened. The pendulum goes back on the clock for further testing.

I’ve not been following this thread as well as I should have, but there were a few other questions earlier.
To make sure the holes on my plates lined up as well as possible, I had a jig clamped on the mill table with some bosses that the plate was pressed against before clamping them down. This ensured that each plate was using the same datum.

Also there was a question about making the Titanium escape wheel. I used the profile cutting method on a Sherline Accupro. The blank was turned first and then dropped into a holder which doubled as an oil bath.



There’s probably other stuff I’ve forgotten to answer, but I’ll try to pay more attention to this thread. I’m very pleased to see your progress Chris!