No main barrel endshake on Waltham model 1900

[AndrewSi]

I’m working on a Waltham model 1900 (0-size pocket watch) with a motor barrel and I’m finding that there is essentially negative endshake- if the barrel bridge is tightened down, there is enormous friction between the bottom of the barrel and the main plate such that a tremendous amount of power would be lost, if indeed it can turn at all.

I’ve checked for obvious reassembly errors such as the barrel arbor square ends (both of them) not being properly engaged and other things that would cause the total barrel/arbor height to be too tall and account for all of this friction, but I’m not finding anything. I’m wide open for suggestions here- there are no jewels at either end of the arbor, but I would think that wear of bearing surfaces in the bridge or main plate would cause more endshake,  not less.

Anyone have a bright idea here?

[RichardHarris123]

Could the bridge be bent? 

[nevenbekriev]

At least some pictures will be needed. If the movement was in my hands, I would tell the reason. But it is You hands

[watchweasol]

Hi from your description it’s only when the bridge is tightened down.  Which would lead one to think the bridge is warped in some way binding the arbour.

[AndrewSi]

Problem solved.

For some bizarre reason, the hook on the wall of this barrel is not properly centered vertically, but is oddly high on the wall, maybe 3/4 up the way up. When replacing the mainspring, this caused the outer coil to be displaced upwards as well such that it protrudes out of the barrel and caused the barrel lid to not sit quite flush to the barrel. Since this is a motor barrel, the lid is actually the first wheel and inner coil tube/hook all in one piece, with no “snap down” action that would have made the problem more immediately obvious. Maybe with an older mainspring the spring’s end hole was enlarged such that this wasn’t an issue, but hard to say how it ever worked otherwise.

Replacing the barrel with one from a different model 1900 where the hook was properly vertically centered allowed the lid to sit flush without mainspring interference and the friction problem went away.

The bridge was far too thick to be bent (and isn’t), for those of you thinking that was the problem. Placing the removable arbor in the watch without the rest of the barrel proved that the proper end shake was actually there as long as the overall height of the assembled barrel was correct.

Edited May 11, 2024 by AndrewSi

[CYCLOPS]

the arbor square out of place and mainspring thickness/height is what I would double check on this model....