Fine tuning

[sgoodstal]

First I’d like to give kudos to William for his testimonial great job. My question which I know is not a simple one and I know different situations call for different approaches. I have mastered figuring out why a pocket watch is not running and fixing that problem but now I need help in that 2 minutes fast or slow per day watch I call the fine tuning I guess? Could someone try explaining balance screws. I have a Hamilton 992 that I have running good but losses 2 minute per day. I don’t believe that it has mean time screws and im a little intimidated when it comes to adjusting balance screws. From what I have read too increase seconds per day you should screw the screws closest to the split across from each other on the balance wheel in, but they seem to already be screwed in all the way. Any help and a little reassurance would go a long way. Thanx

[willofiam]

Thank you!!! William

[arutha]

With that amount of loss or gain per day it is going to be down to adjusting the length of the hairspring and not screw adjustment on the balance wheel. If the watch is losing 2 minutes per day and you are at the end of adjustment on the regulator then you will need to shorten the hairspring a touch by unpinning it and pushing it further through the stud. The only problem then is that this will put the watch out of beat. To rectify this you need to move the hairspring collet on the balance staff until you get an equal beat again. Do a little research on putting a watch in beat and you should see how its done.
Paul.

[Bob Tascione]

That’s an excellent question Sgoodstal.
Paul is correct about possibly being the hairspring length. I’ll add here though that it could also be a number of other things. First to answer your question about the Mean time screws. Not sure about the amount of effect a turn will have on the 992 but I know that for most Waltham 16 to 18 sizes a ‘half’ turn of ‘both’ timing screws will cause a rate change of about 2 1/2 secs. per hour. So if your 992 is similar to Waltham and you have a full turn left you should be in range for regulator adjusting.
I have a few questions though before making any timing adjustments.

How does it do in other positions? Is it consistent or does it change drastically when moved to any other position?

How is the balance amplitude in both vertical and horizontal positions and does it have a quick or sluggish recovery time when changed between positions?

Do you see any washers that may have been added to any screws?

Have you cleaned and serviced this watch? Probably did that but thought I would ask anyway.

Is the hairspring making contact with ‘BOTH’ index pins during vibration?

Please let us know when you get a chance.
Enjoy,
Bob

[sgoodstal]

Bob I will try to answer your questions as best I can.
First: the watch has been cleaned. I had to change the balance staff and re-attach roller jewel plus it has a new spring.
second: Dial up or dial down no change. I will run tonight pendent up to see what happens.
Third: The amplitude seems good all of 270deg on full wind, it does drop down some pendent up but recover immediately
Fourth: I see no washers on any of the screws. I wish it was that easy!!!!
Fifth: I believe that the index pins are set properly but I will tweak a little and see what happens

As to Arutha answer the stud does not seem to have a pin like many I have seen. The stud is round and the hairspring does not go all the way through. But I will drop the hairspring and take another look. I guess it held in some how.

[sgoodstal]

update: watch running in pendent up lost about 4min in 24hr. apposed to dial up was 2min in 24 hours

[Bob Tascione]

Sgoodstal,

Since the balance amplitude is good and balance motion recovery time is quick I think your timing problem does have to do with the balance assembly.
When you say that you changed the spring I’m assuming that you are referring to the mainspring and not hairspring. It is possible though that the hairspring may have been changed sometime in the past. The fact that the mean time screws were already turned up against the balance rim could mean that someone in the past had to deal with this slow rate problem. You mentioned in your first post that you didn’t think this watch has mean time screws. You may be correct as I don’t have a 992 here to check out but I was under the impression that the 992 split balance has 2 mean time screws and the 992E (elinvar) solid rim has 4. I’ll have to do a little digging through some books to find out.
Because of the extreme positional error it’s very possible that the balance is way out of poise. Here are a few things you can check.

1. Check the balance in a truing caliper to determine that it’s true in the flat as well as in the round. It’s very possible that the staffing process has somehow distorted or stretched the balance arms. This can result in the rate problem you’re seeing.

2. Check that the staff is securely staked to the balance. A loosely staked staff is a fairly common problem.

3. Check for concentricity (If the staff is staked off center).

4. Check that the roller table is secure on the staff.

5. CHECK that the ROLLER JEWEL is not loose. VERY COMMON problem. Also check that the roller jewel is straight and not jamming in the pallet horn.

6. Make sure that the hairspring stud is tight in the balance cock hole and that the regulator pins and regulator are secure.

7. Check that all balance rim screws on one arm of the balance match the screw location of screws on the other arm. Same hole pattern beginning from balance arm to end of each rim.

8. Check that all balance screws (not the mean time screws) are turned and tightened down to the rim.

9. Check the poise of the balance.

10. Cracked, shattered or loose balance hole and cap jewels.

Let us know how it goes.
Hope this helps,
Bob

[sgoodstal]

Thank you Bob, looks like a busy weekend. Many
Of the causes you have stated I have checked
But will check again. I also need to dig a little
On the mean time screws but all the screws
Look the same I thought that the mean time
Screws were gold or platinum or a mother metal
Besides steel but I’m sure I could be wrong.
One thing I did notice under magnification last
Night is the safety roll does have a hair line
Crack but being a safety roller and not touching
The keel whole I would not think that would
Cause a timing issue. Scott

[Bob Tascione]

You may be on to something there about the timing screws Scott.
I’m not sure whether they are always gold or platinum on 992s. Randy’s pretty up on Hamilton so maybe he’ll see this and can let us know. The screws will usually look different than the other screws on the rim. The screw is usually longer and the fit is tight yet smooth to allow for easy adjustment and to stay in place after the adjustment has been made. This is unlike the other screws which are often loose and sloppy if not snug against the rim or washer.
As far as the safety roller goes I would think that there would be some loss of motion to the balance if dragging on something or if it is in someway being interfered with by the guard finger. Maybe not though. Also if something is keeping the safety roller from moving up against it’s locating shoulder or part of it is sitting a little too low due to the crack it could be contacting the balance jewel setting. I don’t think this is the case though as it would probably be running slower in the dial up position rather than pendant up..which is the opposite of what’s occurring. If this is a two piece double roller and you would like even more to do this weekend you could always remove the safety roller and do a test without it to see what happens.

Enjoy,
Bob
ps…if possible please post the serial number (or a pic).
Thanks

[randy]

I’ve seen 992B balances with 4 screws. Two outside the arms, and two more 90 degrees from those.
Not sure that all of the 992 series balances are the same though.
They will have smaller heads than the other balance screws and will be longer.
I can’t say that they are of different alloy though.
So if you have the other two, I would start by moving them the same amount as you did the first two, and see what the result is.

Is there any chance that the staff is distorted a bit ? I’m thinking about the fact you are stating that it lost more time in the pendant up position than face up, which also makes me wonder if it’s the correct diameter as there’s more than one staff called out for the “regular”992…you may have been sold the wrong one…
There are three called out on the Jules Borel site for the 992, not the “B”or “E ” .

22BB/56 $10.00 Add to Cart
STAFF, SR P11 COL .76
22BB/57 $10.00 Add to Cart
STAFF, DR P11 COL .76
22BB/58 $10.00 Add to Cart
STAFF, DR P10 COL .98

Randy

[chris mabbott]

Hey Scott,

When you said “re-attach” the roller jewel? Can you explain that please and mention how you re-attached i.e. had it fallen out, was it just loose etc

Also, is the FLAT on the jewel facing towards the pallet fork? Did you measure the jewel to make sure it’s the right size?

When you remove the balance assembly the next time, you might want to try this, just to eliminate another possibility.

Take either a black felt tip, or some prussian blue, and apply it to the OUTER circumference of the large roller plate, the jeweled one.
We want to check for excessive contact here with the brass pin on the pallet. Something knocked the roller jewel out, but what?

Did you polish and de-burr all of the pivots in the train before re-assembly?

Did you check the end shake on all the wheels under “no load” conditions?

Did you run the movement freely before mounting the pallet fork/balance assembly?

Did you lubricate or clean the new mainspring?

How are the contact points for the MS arbor, are there any burrs rough spots etc.

When you replaced the hairspring, did you put it back in the same position? If there was a crack in the roller plate and it rotated while mounted, this could throw everything off & as Bob has mentioned, POISE is very important. When you poised the wheel, the roller and jewel were in place, correct?

Which throws me back to…. If you poised it, and it was ok, i.e. the wheel would come to rest in ANY position, never the same spot, did you adjust the weight?

What condition is the hairspring in?

Did you burnish/polish the pivots on the new staff?

As the other guys have stated, we never know who has messed with them before they arrive in our hands, but my own personal rule of thumb is that the absolute LAST thing I will attempt is to adjust the balance screws, it can be a waking NIGHTMARE if you’re not accustomed.
Usually when you become familiar with balances, you can tell if the screws have been messed with by studying the position of ALL screws and of course looking at the dirt/patina build up, not hard to tell if a screwdriver has been in the slot 😆
It is also not uncommon for the timing screws to be all the way in, but the two meantime screws should not be, usually they are half, but that is not a rule.

Photos are very helpful in remote diagnosis, if you can post some close ups of the balance, the pivots etc and tell us the serial number etc

Chris

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