Full plate watch, Suitable tool for adjusting & testing pallet stones?

[mbwatch]

I find myself in a frustrating situation, and if I have learned anything yet it's that there might be a specific old tool to get me out of it.

I am rebuilding an early grade Elgin 18 size full plate movement, just restaffed and installed a new roller jewel. Next I found that the pallet stones were loose and added shellac to them, reassembled but the watch does not run. Observing the escapement through the holes, it is clear the entry stone needs to move in slightly. So I know what I need to do at this stage, but I fully expect to need a few adjustments of one or both stones. I don't want to move the banking pins because it did want to tick before I noticed the pallets were not secure.

Question is, on a full plate movement this is incredibly inconvenient to make a change, let the shellac harden, and reassemble the entire full plate watch in order to observe the escapement action.  It can only be seen from the dial side through the small holes in the pillar plate, so even the balance must be installed in order to manually operate it from the back. Anyone know how this was done 120 years ago? Is there a tool or fixture that can be used for the job outside the watch? Depthing tool maybe?

You all like pictures, so here are some. Final cleaning has not happened yet, thus the dirt and oil on the 4th wheel jewel.

[Randy55]

Afraid this is where it could get down to old school adjustment and observation.

There are pallet setting tools..but the calibrated ones aren't cheap.

The observation holes in the plate will allow you to see if you have one or both stones hanging up/ not engaging on a tooth, That would ofcourse require you to disassemble, heat/move the jewel in/out as required..by eyesight and experience. It's truly trial and error until you get close enough that you could make small adjustments with the banking pins until they drop to the lock freely.

You can use a Potence tool to help hold the rok in place during reassmbly.

Here's a pic of one...made with a piece of old 18s mainspring

You just fold over a roughly 2 inch piece, then file a slot on the end that engages the pallet fork arbor

Edited 8 hours ago by Randy55

[mbwatch]

1 hour ago, Randy55 said:

Here's a pic of one...made with a piece of old 18s mainspring

Oh that's neat. I typically use a thin strap of rodico laid over the pallet fork to affix it to the upper plate but it can be hard to retrieve sometimes.

And as I did more research, I may have just found your own earlier explanation: https://learntimeonline.com/forums/topic/potence-clip-for-full-plate-p-ws/