Hermle 130-070 regulating question

[JeffG]

Good Day!
I'm looking for advice regarding difficulties in regulating an Hermle 130-070 movement in a New England Clock case circa '84.
Using the Clockmaster app I have graphed the BPH over a week and found a very linear acceleration of the S/D Error from .05 seconds/day when fully wound to 84 seconds/day a week later. This caused again of 4 1/2 minutes in a week. Should I replace the spring and hope for a more steady rate, or is there a way to adjust some of the difference out?
Also, I have read that rotating the weights around the floating balance wheel by 1 dot should equate to 10sec/day and I have not found that to be the case. Adjustment seems to be wildly arbitrary and hit or miss.
P.S.- the balance is clean, un-lubed, and spinning about 540 degrees (based on slo-mo iPhone video)
I'd appreciate any advice/education.

 

[Dick Feldman]

It is a common practice to zero in on escapements and mainsprings as a possible source of problems. Mainsprings are subject to certain forces and generally a new, replacement mainspring will operate as the original one did. They have their limitations. Balance escapements, if they work, are victims more often rather than the cause of operating problems.
Your clock is 37+/- years old and if nothing has been done to it, probably it is suffering from power loss between the spring and the escapement. Power loss due to friction due to wear due to extended use. Think of the situation as a sick cow. Would you look at the mouth or the other end for a cure?
Maybe your analysis is too technical. Clock regulation is normally done over a long period of time, like a few days or a week. During that period there are things happening to that movement and escapement to slow the rate and to speed it up.
One of those things is warn period on any strike/chime train. The actual rate on any style escapement will vary a bit over a short duration, but actual useful timekeeping will be determined by long term operation. If the clock has hands, the closely studied rate will be faster between the hour and half past the hour due to the weight of the minute hand. As the minute hand is raised again to the hour position, the rate will be slowed due to the weight of the minute hand. Your highly technical and accurate measurement method may be picking up that small increase/decrease in rate. You could eliminate that variable by taking the hands off of the clock but what is a clock without hands?
Your biggest enemy with clock repair will be power loss due to friction due to wear due to long operation. If the clock runs, keeps good time over a long period of time, run it and enjoy it. Don’t fix it till it is broken.

Best Regards,

Dick

 

[JeffG]

Power loss due to friction...
Clock regulation is normally done over a long period of time, like a few days or a week.

Thank you for your reply.
After weeks of chasing a consistent rate on a newly cleaned and lubed clock, I finally attached an external pick up to the clock and opened up the Clockmaster app. I plotted points on graph paper for a week from a full wind to see what's going on.
I plotted 2 points a day, AM and PM and each of those points was an average S/D Error over 2-4 hours. No hour by hour numbers here. The plotted points after one week of runtime showed that the clock sped up significantly over that week ( .5 -> 84 S/D) and the points were very nearly in a straight line.
As for power loss, I understand that as a balance wheel rotates less, it "beats" more quickly. The wheel had a very healthy rotation (well more than 360) before and after my test run, but I can't quantify how much less.
Maybe that is what I should watch?

I'll just leave this here ->

 

[Dick Feldman]

I believe you are measuring the results of something other than problems with the escapement or mainspring.
Granted, your mainsprings will have limitations but the most important limiting/controlling force is likely wear.
Wear as pivots moving around in their holes.
Balances behave rather erratically and mysteriously with inconsistent power.
Clock movements, like all machines will wear with time.
Have you, with your analysis, let down the mainspring/s and checked for pivots loose in their respective holes?
D

 

[JeffG]

Yes. I disassembled, cleaned, and lubed the movement a couple of months ago. I wouldn't call the pivots tight, but they are in better shape than my skill level is likely to improve upon.

 

[Willie X]

Listen to DF.
And, a 37 year old 130 is doing well to run at all ... Haveing a good balance rotation and a rate within 4 minutes per week would be very good.
Note, even what appears as slight wear in these little clocks, can cause an erratic rate.
You are well past the service life, so just try to enjoy what you have there for 'maybe' a few more years.
Willie X

 

[JeffG]

Thank you Mr. X for that perspective. I have some 100 year old clocks that I've tinkered with that are consistently within a minute +/-, so I've assumed that this much newer movement should be able to do better than four.
Thank you both for your time.

 

[shutterbug]

There is one more thing to think about. Some clocks came with "stop works" to keep the spring from being wound fully. Your clock may not have them, but if you count the number of winds on the mainspring after a week of running, you'll know how many turns it needs every week. The second week, wind one full turn less and see if it helps regulate the clock over a week' run. You might have to back off a turn and a half or even two full turns. The idea is to keep the spring from ever being fully wound. It is very common for clocks to run a little faster when fully wound than when they are nearly depleted. I'm thinking that might help you get things balanced out better. When you find the "sweet spot", you can just wind the number of turns you noted it needs every week and it will stay there.

 

[Dick Feldman]

If your most likely source of problems is wear, why not find out a viable solution for the wear.
It was stated earlier that many clock performance problems are blamed on one end or the other of the clock movement, specifically the main spring and the escapement.
All too often those are victims rather than causes of clock malfunctions.
If you changed nothing with the clock other than to solve the wear, my bet would be more reliable operation.
You likely do not have a spring problem.
You likely do not have an escapement problem.
Clean, oil and adjust have done little or no good.
That is what I think.
D