Bulova 11B Mainspring Barrel wobbles

[cortman]

I am in the process of servicing and restoring a Bulova 11BL manual wind movement. The movement looked to be in excellent condition when I opened the case and it ran without problems.

I'm reassembling it currently and I've noticed the mainspring barrel wobbles significantly even when the bridge is screwed down. The bridge is fully seated (I've checked many times) and there is no debris or anything around the mainspring at all. 

I don't recall it being this way when I disassembled it, but I'm at a loss as to what's causing it. I did pull the mainspring apart to clean and grease it, but it seems to be fully seated with no issues that I can see.

To my eyes there appears to be no wear at all on the mainplate or the barrel bridge, certainly not enough to warrant such a sloppy fit.

I've included pics of the mainspring, plate, and bridge. Here is a link to a video showing how drastic the slop is: https://imgur.com/a/v4P9CIP

I must be doing something pretty dumb and simple but I can't figure out what!

Thanks in advance.

[Nucejoe]

Hi there. 

Check if the mainspring coil has coned near the arbor. 

Regds 

[anilv]

eyeball the barrel pivot (both sides) as you 'rock' it. If you can see movement then the pivot is worn.

Barrel pivots usually wear in one side, usually opposite the centre wheel. So if you apply pressure on the outside edge it will rock but it may not rock as much at 90deg on either side.

Anilv

Edited July 28, 2022 by anilv

[mikepilk]

Assuming that the bridge was properly seated (?), then you have a lot of play in the top bearing.

You can close it using a rounded punch and smoothing broach - as shown here :  https://youtu.be/rshFo-KGgjY

[cortman]

Thank you very much all for these tips- I have had to set this project aside for a couple weeks, but I will give some of these a try and report back with my success or failure then. Thanks!