20th c escapement Revue 31 (JW Benson) Overhaul (running fast)

[gmorse]

Hi Stephen,

Will the Alum hurt the jewel settings?

No, it will only attack the steel. There may be a little discolouration, but that will clean off.

Regards,

Graham

 

[Skutt50]

Alum should only be agressive to iron (steel) but I have had some other stuff that got discolored. Don't remember what it was but it was easily polished out.

Heating the solution will speed up the process. Cold solution may take a day or two. Just check that there is not a small bubble formed over the screw part.

If there are some other steel parts you can't easily remove from the plate you can cover them with wax.

 

[svenedin]

Alum should only be agressive to iron (steel) but I have had some other stuff that got discolored. Don't remember what it was but it was easily polished out.

Heating the solution will speed up the process. Cold solution may take a day or two. Just check that there is not a small bubble formed over the screw part.

If there are some other steel parts you can't easily remove from the plate you can cover them with wax.

Thank you both Skutt and Graham. There’s only the broken screw in the plate now. I have a double boiler going (glass pudding basin over a saucepan of water) with a tiny gas flame keeping it hot. I had a block of alum for stopping bleeding from shaving cuts. Screw remnant turned black quickly but it is going to take a while for it to fully dissolve.

 

[svenedin]

The alum worked well. The replacement jewels are seated and screwed in. Assembly and testing tomorrow.

 

[gmorse]

Hi Stephen,

Screw remnant turned black quickly but it is going to take a while for it to fully dissolve.

It often seems that the alum is working very slowly, but then suddenly, it's worked and the steel has all vanished.

Regards,

Graham

 

[svenedin]

That is exactly what happened Graham. Nothing much seems to happen then suddenly the screws are gone.

I found the chaton screws very difficult. They are rather small, are prone to cross threading and have extremely narrow slots in the head. I sharpened my screwdriver well but it was still an issue to get the screwdriver in the slot.

 

[gmorse]

Hi Stephen,

Balance screw holders with the sliding sleeve to close them are useful in placing these tiny screws, but the Bergeon ones are pretty expensive, (not sure about the Indian versions, very much cheaper, but the finish is probably inferior). I did make one myself once for this sort of job.

Regards,

Graham

 

[svenedin]

Hi Stephen,

Balance screw holders with the sliding sleeve to close them are useful in placing these tiny screws, but the Bergeon ones are pretty expensive, (not sure about the Indian versions, very much cheaper, but the finish is probably inferior). I did make one myself once for this sort of job.

Regards,

Graham

I have one of the Indian ones. I’ll give it a go!

I now have more bits from scrap Revue movements than I think I could ever want. At least I will never be afraid of losing a screw again when working on these. I do have 3 or more watches with the same movements so this is not a bad position to be in. I found to my delight that one of the scrap movements has a perfect 2 piece dial that is identical to one of my watches with a cracked dial.

 

[svenedin]

I assembled the watch this morning. I moved the wheels up and down gently and noticed that one of the chatons was not screwed down securely as it glinted in the light so I rectified that.

The wheel train moves freely now.

All is not well yet though. I am not happy with the balance. The pivots look fine. Not broken, not bent, they look in good order but the balance does not swing freely and comes to an abrupt halt. It swings well enough dial up but not dial down. I think the problem is that the endstone setting on the top of the balance cock is not secured well enough. It is the type with a bevelled endstone setting that opens out a split in the circular part of the regulator. Either it is not down enough or too far down and this is affecting the end shake of the staff. Or maybe it is the setting on the dial side, I am not sure what this balance behaviour points to?

I have exhausted my concentration for now and will look again in due course. Removing the balance from the balance cock and refitting is not something I would attempt when tired.

 

[Skutt50]

I assume you are testing the balance without the pallet fork installed!

It swings well enough dial up but not dial down.

My first check would be that the hairspring and balance wheel moves freely in both positions. Is there some endshake? No touching of the balance wheel of the center wheel or the pallet cock/bridge, no hairspring touching the balance cock...... .Sometimes you can hear an odd sound if you listen closely......
If wheel and hairspring are free a problem in the dial down position to me would indicate either a problem in the main plate jewels OR a musheroomed pivot in the balance cock.

Re-clean the jewels and inspect the balance pivots again searching for either a bent or a musheroomed pivot.

 

[svenedin]

Hello Skutt. Yes no pallet fork. There is a little bit of endshake that I tested by gently lifting the balance wheel with brass tweezers. I will do as you suggest. It's a bit odd. I've probably missed something obvious.

 

[svenedin]

I can't work out what is wrong with the balance right now. There seems to be insufficient endshake. The pivots look OK to me and they are definitely in place correctly but when the balance cock is tightened down the balance is not sufficiently free. I have in the past come across watches where a piece of paper has been put under the balance cock to correct this but I did not notice that with this watch.

I did want to test whether the watch can work after what has been a bit of a trying overhaul so I transplanted a balance from a spare movement and off it goes (it's not properly in the case but needed to be in the case so I could wind it a bit). The is no lubrication anywhere in the watch at this stage except the mainspring.

It has to go to a watchmaker to replace the dial side centre wheel jewel so this may be as far as I can get. The balance problem could be addressed at the same time.

Revue 31 JW Benson (partway through repair)

youtube.com

 

[gmorse]

Hi Stephen,

It's possible that the balance staff you have is a replacement; even factory-sourced staffs sometimes have to be 'eased' if they're a tad oversized. Next step, a Jacot tool!

Regards,

Graham

 

[svenedin]

Hi Stephen,

It's possible that the balance staff you have is a replacement; even factory-sourced staffs sometimes have to be 'eased' if they're a tad oversized. Next step, a Jacot tool!

Regards,

Graham

Yes very possible. I might try the piece of paper trick.

 

[bruce linde]

what a great and informative thread...

 

[Skutt50]

When you say insufficient end shake how is that measured? You had some end shake as per your post #61. That should be enough. Specially since the watch runs Dial Up.

Have you tried the balance in the donor movement you transplanted the functioning balance from? Do you have a caliper? If so measure the diameter of the balance pivots. This may indicate any mushoroming......
How is the end shake with the transplanted balance?

 

[svenedin]

When you say insufficient end shake how is that measured? You had some end shake as per your post #61. That should be enough. Specially since the watch runs Dial Up.

Have you tried the balance in the donor movement you transplanted the functioning balance from? Do you have a caliper? If so measure the diameter of the balance pivots. This may indicate any mushoroming......
How is the end shake with the transplanted balance?

In my earlier post there was a bit of end shake. It's not measured, it was just I could feel it and see it as I lifted the balance wheel with tweezers whilst installed in the watch. I think at that stage the balance cock was not fully tightened down. I am always nervous about fully tightening down the balance cock screw if the balance will not oscillate freely because it usually means a pivot is not located properly. I took the balance off the cock (again) and checked the pivots. I don't have a caliper, only a vernier (which isn't very accurate). All I could do was compare the pivots with a known good balance by eye (the one running in the video in post #62). I could not see anything obvious wrong. I checked the endstone settings were screwed down properly -the dial side was not. I put the balance back and fully tightened the balance cock and it just would not swing for more than an oscillation or two dial down but will swing quite well dial up. I then got fed up with it and put the good balance from another movement in and that was fine so I put the pallets in and it ran well straight away.

I also checked from the side that nothing was rubbing as you suggested and I could not see anything. The overcoil is not touching anything and I could also see that the hairspring was not rubbing the arms of arms of the balance wheel underneath either. Furthermore I took the endstones off and re-cleaned all 4 jewels and checked again they are not damaged.

I haven't checked the balance in the donor movement.

EDIT: I fitted the balance in the donor movement (balance and cock) and it swung fine!!!

I'm stumped basically.

 

[svenedin]

Skutt you're a genius with your suggestion to try the balance in the donor watch!

Because the balance worked in the donor both ways up and only dial up in the overhaul movement I worked out it must be something to do with the dial side endstone.

I started to unscrew the endstone setting/plate and noticed it is smaller than the depression it sits in and tend to swing over to one side of the depression when it is screwed on. I adjusted it and the watch is running both ways up!

It's so out of beat it's ridiculous but it runs. Sorting the beat out is for tomorrow (I do have a proper collet adjusting tool but I must read up how to work out to adjust in the right direction).



Limping along out of beat very badly (very minimal winding):

Pocket watch out of beat

youtube.com

 

[Skutt50]

Since it runs Dial Up there is enough endshake.

The balance running in the donor movement could indicate that the balance is OK. Did you inspect the jewels in the donor movement?

I think your next activity shpould be what Graham suggested namely Jacots Tool.

EDIT: Glad to hear you found a cure for the problem. Congratulations!