Waltham 620 Pocket Watch Restoration

Next on the bench at the Walnut lab is a 1902 Waltham Grade 620, Model 1899 from F-chat's very own, @PeterS .

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When Pete had first reached out to me, he'd told me the piece didn't run at all. I believe a jeweler had told him it just needed a good clean. Let's see if they were right, shall we?

I removed the movement from its case (what a beautiful case!) and started poking around to see what there was to see. It wouldn't run, as was expected... but something was weird. The balance would spin freely to the extents of its arc but immediately slow to a stop in the center where the roller jewel would contact the pallet fork. Odd. I've never seen that before. I completed the take down of the movement and document each step with photos. This helps me look back and see if I've missed a potential issue later on but it also creates a roadmap for reassembly.

Next, I started under the microscope to see what was going on with that roller jewel/pallet fork interaction. Nothing looked strange with the balance assembly and roller jewel. The pallet fork though... I think I figured out what was causing that strange issue. At some point in time a "questionable" repair was attempted. The safety pin on the pallet fork, which should be hardened steel like the fork itself, was replaced with a piece of brass wire.

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As of tonight, the Waltham goes back into the "client" drawer of my bench read for the next steps.

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The more I look at the parts, the more I feel I agree with what @ArtS has said. That safety
pin/post would be really easy to replace with a proper steel one. Nothing else I can find requires replacement, just some touching up the polish.

I look forward to getting my lathe out for this!

 

Cleaning has started. It looks like all of the jewels are still good which size great news. In fact, aside from a new mainspring and fixing that wonky safety pin, there is only one other item I’ve found that I need to address and that is the inside surface of the mainspring barrel cap / ratchet wheel. The plating is wearing/chipping off. I’ll want to get that smoothed out before we put a new spring back in there. It should be easy enough to chuck in on the lathe and clean that up. Plus, I keep thinking about getting a plating system for the lab; between this and other projects, it is probably time to pull that trigger.

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Now that all of the components are cleaned, I checked each wheel/staff's fitment into its jewel bearings. Those surfaces must be like glass because they spin so free and smooth! Amazing. Definitely not a friction at the bearing issues on this piece. Next steps are (1) order a new mainspring (2) clean up that plating where it is flaking (I will be electroplating the cleaned/polished surface with nickel) and (3) replace the wonky safety pin in the pallet fork.

 

I was able to remove the brass pin from the pallet fork last weekend. I will be using some blue-steel pinion wire to replace it but will have to carefully work it down to a polished press fit then file to length/fit. Time consuming but not technically difficult.

I also finally ordered an electroplating kit which will let me properly nickel plate the surface of that ratchet wheel after I get it smoothed out.

 

First step in replacing the safety pin is to measure the base of the brass one and see what we’re aiming for.

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See it? No? How about now?

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Yeah… me neither, well, ok I can kinda see it. Just trust me that it’s there at the very end of the calipers, ok? Let’s see what I have for pre-hardened, pre-tempered “blue steel pivot wire”. This looks like a good place to start.

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Because this has already been treated, finding something very close to size and hand working it with abrasive paper is going to be my method of choice. Starting around 800 grit and working to 3000 grit then with various diamond pastes to get a good shine on it.

 

I’ve been working on getting the mainspring barrel’s plating issue cleaned up using various rubberized abrasives.

Before:
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Plating mostly removed:
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Beginning the polish:
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Ready for plating (you can see some pitting and marring that will need to be cleaned up during plating):
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Today I attacked that safety pin on the pallet fork.

(1) The first step was to get the 0.329 mm Blued Pinion Steel (from post #9 of this thread) chucked up in the lathe. I intended to do this with just sand paper at first but that didn't seem to be cutting it (pun intended!). I switched over to jeweler's files using a small piece of softwood to support the material in the chuck as it was sticking out pretty far given its diameter. Once I was happy with the diameter I went back to the paper and eventually a wool wheel and polishing compound to clean it up. The paper towel gets draped over the bed of the lathe so I don't cause any rusting when I use it to rest my hands on it for this type of work. The lathe itself is controlled with a simple on/off foot pedal switch. The speed is dependent on the pulley combination selected for the belt drive.
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(2) Here is what the turned/polished part looks like next to the pallet fork after it came out of the chuck. The first photo is before the wool wheel and polishing compound. The end is tapered on purpose so I could get it through the existing hole in the pallet without issue and press fit at the other end. Second image is after clipping the excess off.
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(3) Here we have the pallet fork with the safety pin set in place on my staking tool. The green putty is my best friend, Rodico! This stuff is amazing.
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(4) Now that the pivot has been pressed into the pallet, we clip the excess and file flush. Please ignore the waxy stuff on the lower side of the new pin. It would appear that I need to do a thorough cleaning of my staking tools.
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(5) The last step is to do the same for the top of the pin so that it cannot interfere with the balance wheel. The first picture shows how much that tapered portion protrudes above the roller table. The second is after clipping. As you can see, it will serve its purpose now and hopefully not cause any interference issues. The bad news is that when I was checking fitment I realized the lower balance staff pivot is bent. Apparently I had checked all of the wheels/pinions but neglected the look at the balance wheel assembly. This can be seen at the bottom of the first photo below with the second photo being after I attempted to straighten it. I'm about 50/50 with fixing these bent, hardened steel pins, but this one was really off and unfortunately snapped. Without a straight pivot, the balance would bind or wobble as it swings, either would make it incredibly difficult if not impossible to accurately adjust and maintain timing. A new staff will be sourced shortly. Fortunately, these things are fairly easy to find and for American manufactured watches such as this.
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(6) And one last view, from the side, of the finished product.
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Today I setup my new electroplating system. After a few tests on other parts to figure out how to get it to work properly, I set about to replate the inside of that mainspring barrel from post #11. It is difficult to get a good picture of it and there definitely a bit of pitting that I've not been able to clear up, however, it is now plated and polished and should be a lot less friction on the new mainspring as it is wound and uncoils. I've gone over the surface a number of times with a 0.5 micron rubberized abrasive stick and followed that up with some rouge on a wool wheel.

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The new balance staff arrived today. Working on balance assemblies used to terrify me. I’ve done it so many times over the past few years though that I now realize it is pretty straightforward. I guess I'll give myself a big old pat on that back for that personal growth.

(1) New balance staff next to the original roller table.
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(2) Set everything up in the staking tool...
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(3) ...and press-fit it into place.
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(4) Time to add the split-ring bi-metallic (thermal compensating) balance wheel to the set.
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(5) Just a little tap or two is all it takes.
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(6) And finally the pièce de résistance, the hair spring.
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(7) The whole gang is back together again!
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Lots of progress on reassembly today. A few minor issues yet to deal with but it’s all “just” adjustments. (1) The mainspring is slipping which is usually an easy fix. (2) I need to adjust depthing of the balance jewels for the new staff as it is binding a bit at the moment.

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After several hours of work today, the mainspring is still slipping after about 1.5-2 turns (out of 8 for a full wind). I’m going to have to take it out and work on the curve where the tooth on the arbor grabs the spring to stop the slipping.

In every position other than dial down, it runs really well. In dial down, the amplitude lowers significantly and it loses a lot of time. I suspect there is still an adjustment issue between the capstone and bearing on the mainplate side which is allowing the staff to “fall” too far into the bearing and the shoulder of the pivot is getting too much contact.

Sometimes it is easy, sometimes it’s a complete pain. I’ll get there though!

 

Today I can claim victory over that slipping mainspring. I had to do a little bending, filing, grinding, and some swearing but it will now take a full wind!

I still cannot figure out why the amplitude drops when the dial is down but is fine in all of the other positions though. She’s all back together though as I don’t need the movement apart to access the balance.

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Mea Culpa

In my struggles to fix these last two issues with Pete's watch, I went and bought myself a spare movement of the same make/model. This helped to find the issue with the mainspring. I got everything back in the case, fully wound, and ticking away. Last night when I checked on it it had become over-banked and stopped running. For some reason, I decided to look around the assembly on my piece and found that same "wonky" looking safety pin in place. Dang it! Apparently, this is how it came from the factory. The hole on the pallet fork is too far from the notch in the roller table for a straight pin to work hence the weird squashed looking bend.

In hindsight I now see that I jumped to a conclusion of assuming the pin was wrong and that was the problem without completely inspection the balance. That's why I missed the bent pivot which is likely what was actually causing it to run incorrectly.

I have taken the factory correct pallet fork from my movement and installed it in Pete's watch so it is back to how it should have been. I will have to make some adjustments to the beat error but at least I know when I send it home, it is as it should be. Moral of this story: make sure my excitement doesn't get ahead of my work.

@PeterS , I'm sorry about that mistake and the time it added!