Re: Pendulum adjustment
John,toggle quoted messageShow quoted text
In the original Synchronome, there is a brass bush fitted into the hole in the bottom of the bob, with a hole for the rating screw to pass through. Thus the rating nut is bearing on the brass bush, and not directly on the bob. You are correct that the weight of the bob is born by this thread and rating nut, but it has never been a problem. As for adjustment, I always find that holing the bob while turning the rating nut works fine. There is usually about 1 inch of the rating threaded rod protruding below the rating nut, and this acts as a pointer to measure the arc relative to the beat plate mounted below.
Don't rely on the rating tray for coarse adjustment - get it to within a second or two per week with the rating screw and then make fime adjustments with the rating tray.
From: John Haine <john.haine@...>
To: synchronome1 <email@example.com>
Sent: Sat, 26 Jan 2019 10:56
Subject: [synchronomeelectricclock] Pendulum adjustment
Thanks to the help I got for my enquiry about pallet design I'm making reasonable progress on my re-build. I'm in the process of making a new pendulum, and wanted to tap the collective wisdom on how the rating nut is adjusted.
The synchronome bob is very heavy - mine is ~7 kg - and all that weight is taken on the nut and thread. It strikes me that there will be a lot of friction so turning the nut can't be that easy. In fact I suspect that unless some of the weight is taken off it, and also perhaps the rod held to stop it rotating with the nut, it will be nigh on impossible to turn.
So can I have some advice on the approach people take to adjusting the nit position please? Is it worth considering placing a thrust race between the nut and bob to reduce at least some of the friction? Of does one hold the rod and turn the bob, the nut turning with the bob?