Lenzkirch rate adjuster

[mhamilton]

Hi, I'm hoping to learn how this adjustment mechanism works on my 1890s Lenzkirch clock. Plate is stamped with "47" if that helps ID anything. I do tinker a bit with watches and clocks, but am by no means an expert. I just took this particular clock to a local shop for a thorough overhaul. I mentioned at the time that the front adjustment for fast/slow did not seem to work right, in the past I have always had to adjust using the pendulum screw. 

Long story short--the clockmaker said he could see it moving the adjustment, but couldn't take it apart further to do any more. He said it seemed to be working correctly. With the clock back home, I'm finding this adjustment is almost useless. When adjust it, there are regions of operation with too much slack, like the gear teeth are broken or slipping, and others where it feels like it's binding. The adjustment itself is not useful. In less than 1/4 turn it goes from gaining 5 seconds per hour to losing 5 seconds per hour (overall there are 2-3 full turns of adjustment before it hit the end stops). I can't get any fine tuning out of this.

My question: does anyone have a drawing or photos of what's going on inside this "black box"? I'd like to understand how it works and then decide if I should try removing it to fix. I can see 2 gears on top, I assume there's something like a worm gear internally that raises the suspension spring? The "box" has a seam and 2 screws into the side, so I presume it must come apart. However it may be that it's not able to be disassembled depending on how the gears are staked to the shafts. If that's the case, probably would be best to leave well enough alone and just adjust with the pendulum.

Any advice here would be much appreciated! Thank you,

Michael

[rjenkinsgb]

This is one I got from ebay and have not done anything with yet.

The gearwheel on top turns what is effectively a tiny leadscrew (just visible in the back) to move the middle block up or down, which changes the effective length of the pendulum in the same way the the pins on the adjustment of a hairspring movement can be moved to change its effective length (and resonant frequency).

[mhamilton]

That is very helpful, thank you!

Makes a lot more sense that it's a leadscrew down the center to raise/lower the suspension. So on mine, I should be able to measure a difference in the spring length that's exposed out the bottom at slowest vs fastest setting. The more I look at my photos, it appears this sub-assembly comes off pretty easily, it might be worth pulling off just to get a closer look. I'm not sure the spring is sliding up/down inside this block properly. Knowing this key bit of information, it feels like maybe the gear at the top is stripped from the leadscrew shaft.

More digging to do... I'll do some exploratory and post back.

Edited March 19 by mhamilton

[rjenkinsgb]

The pendulum length does not change (at least in the ones I have), it's the middle block that restricts the spring from bending that moves.

It's a direct parallel to a hairspring adjustment - the end anchor does not move, the moving block on the support spring is like the pins on the adjusting arm at "B" in the image.

 

 

[mhamilton]

Hmm, I think a closer look at my unit will be necessary. It appears from the outside that the suspension spring is pinched by the lower portion of the block (yellow arrow). My assumption was that more or less of the suspension spring was allowed to protrude here as the leadscrew was adjusted. It's not an "open frame" design like the one in your photo that adjusted the touch point on the spring itself. 

Maybe that's incorrect or something else is going on that I can't see. I'm going to try and pull this out and get better photos. 

[oldhippy]

You should be able to adjust the regulation from the front just above the 12 on the dial , you should be able to see a small square a pocket watch key of the correct size will do it or a clockmakers pin vice. The movement is in a a bad condition and needs a good cleaning and polishing. You should be able to see your face on the back plate, that is telling you how bad it is. You won't get good timing from a clock in bad condition. 

[rjenkinsgb]

13 hours ago, mhamilton said:

Hmm, I think a closer look at my unit will be necessary. It appears from the outside that the suspension spring is pinched by the lower portion of the block (yellow arrow). My assumption was that more or less of the suspension spring was allowed to protrude here as the leadscrew was adjusted.

Very possible. I have limited experience with these, just a couple I've done for family.

The one below is my other spare movement - similar adjustment to the first one I showed & also in need of a new pendulum support.

I get the impression that these old French & French style movements were made to a generic pattern with the same visual layout of pivots and wheels etc., but each maker had their own variations in how they made the parts - very much like the "bar" style pocket watch movements, all similar at a glance but different in detail?

Oldhippy is the clock guru, so I'd go with any of his suggestions.

 

 

[watchweasol]

Hi. I have done many of these French type clocks. And as Old Hippy said it in a terrible condition  so massing about with the adjuster is not going to prove anything untill the whole clock is cleaned. Then it’s time to se to the adjustment. As @rjenkinsgb mentioned the spring length is adjusted via a wheel on the top of the block from the front of the clock as mentioned by @oldhippy using the small end of the key ( double ended)  or a pocket watch key. Turning the wheel raises or lowers the spring altering the effective length, speeding up or slowing down the clock. The spring MUST be free in the block but with very little play. The corse adjustment is by moving the the pendulum bob up or down, the fine adjustment by the key. Once you get it apart check that the suspension spring is not cracked , broken or bent. If so a replacement will have to be found (Cousins U.K.)  They vary in length and width. Once cleaned and set up they are good and reliable clocks.

[MikeEll]

One thing I've noticed since I started using Clockmaster for my clock regulation is that clocks typically do not run at a precise regular speed throughout the day, at least not this kind of clock.  This one needs a complete cleaning and overhaul, as mentioned.  But when you have it in good condition, if you watch the going rate over a few hours when measured precisely, you see the speed vary throughout the day.  It's the average speed that can be regulated.  

The front adjuster is for very small adjustments, but you can end up chasing your tail. @rjenkinsgb is right, as you turn the dial adjuster, the block moves up or down precisely, driven by the lead screw.  The point at which the suspension spring exits the adjuster is moved, altering the effective length of the pendulum. Each time you make a very small adjustment you need to leave it alone for a couple of hours to settle. I typically start the clock running to its theoretical beat rate using the pendulum adjuster, and then I fine-tune the average rate using the dial adjuster over days or even weeks.

See the following example for a clock I had on final test.  I was able to regulate this one down to +-4 seconds per day, but you can see the white trace showing the average rate approaching zero as I adjust it, but the green one showing how it varies over time.

 

 

Edited March 20 by MikeEll

[mhamilton]

Thank you all for the replies--

Sorry for the confusion. The clock was just serviced and is not in terrible shape. Please refer to the top 2 photos in post #1. Any of the pictures showing tarnished brass are simply older photos I had of the adjustment block. 

As I mentioned, when turning the fine adjustment on the face, the "feel" is not right. It goes from too-tight to too-loose, and the clock rate jumps rapidly from too slow to too fast. I could make finer adjustments with the pendulum screw. I suspect there is something broken or jammed up inside this block, as soon as I get a moment I will remove this and inspect it closer. 

With respect to the rate, I'm glad others brought this up. On a French-style clock of this vintage (that was just serviced) what is the expected accuracy? I'm not expecting sub-second accuracy here, but if +/- 20 seconds per day is normal, then I will leave well enough alone. 

Edited March 20 by mhamilton

[MikeEll]

32 minutes ago, mhamilton said:

I'm not expecting sub-second accuracy here, but if +/- 20 seconds per day is normal, then I will leave well enough alone. 

I would be perfectly happy with +/- 20 seconds a day

[oldhippy]

Are you saying the first two photos shows the movement just after cleaning?

[watchweasol]

You will probably find the suspension is cracked or bent, probably due to moving the clock with the pendulum attached, jamming the block or I have had them where the screw is gunged up and had to be dismantled and cleaned and a light oil. (Windles).

[mhamilton]

1 hour ago, oldhippy said:

Are you saying the first two photos shows the movement just after cleaning?

Yes sir. That is the clock as received back from the clock shop. It's not a mirror polish, but not tarnished like the other photos. Here's a zoomed-out view of the "after" service. This is from just a few days ago. 

[oldhippy]

I would take it back and ask for a refund. That is disgusting work. This is how the movement should look after polishing, cleaning and having the screws blued. 

[mhamilton]

1 hour ago, oldhippy said:

I would take it back and ask for a refund. That is disgusting work. This is how the movement should look after polishing, cleaning and having the screws blued. 

I appreciate your candid feedback. I agree, the correctly cleaned/polished parts show a true pride in craftsmanship. I'm curious, a full service and restoration like that, what would a ballpark cost be? For reference, I paid approx $500 USD for what I got above. Seems like the typical rate for clock/watch service in this part of the world. But if the job was half-assed, perhaps not worth that price. 

I'm definitely a bit ticked off that I'm having to go back and fix the adjustment mechanism that wasn't fixed before. I might have been better off fixing this entire clock myself. I decided to take it to a "professional" because I didn't feel confident enough to do a service on this. 

[HectorLooi]

How would that level of high shine be acheived?

Does brushing with French chalk produce this kind of shine or would a metal polish, like Brasso, been used.

I know @oldhippy is against the use of rotary polishing machines, how long would it take to polish brass to this level of shine?

And what would be used to protect the brass from tarnish after that?

The brass of the OP's movement looks orangey. Is that due to dezincfication caused by soaking the brass in an acid?

[oldhippy]

$500 USD what a complete rip off. I could have restored your movement to the finish of the example that I posted with all the screws blued better then in the picture for less than that.

 

This is what I used to do. Once everything is apart and that means if it comes apart it is taken apart, remove the springs from there barrels. All of the brass would be covered in Horolene and left to soak, depending on condition for as long as it takes. Scrub with a brush you can by washout brushes at any good clock suppliers, dry in an old rag. Brasso is used to polish all the parts using a brush and your own elbow grease, you need clean soft rag and by hand polish all brass parts to a high finish. Wash out in petrol making sure all the brasso has been removed. Place and cover all parts in sawdust this will soak up any petrol., remove from sawdust and with another clean rag polish all the parts to a bright shine, then French chalk all brass parts with a clean chalk brush it must be very soft. The chalk brush most only be used for this type of work. French chalking prevents tarnish. All screws are cleaned and polished in a lathe using needle files and emery sticks, screws are cleaned in and old watch cleaned, when cleaned and dried, screws are then blued making sure they are all the same colour blue, dropped in oil, removed from oil and washed again in the old cleaner. Don’t forget to clean the barrel arbours remove bur and polish with emery sticks ending with the finest, arbour ends can be polished in the lathe. The fine adjuster square to be cleaned and polished with emery sticks. Pendulum rod can be polished in the lathe. I haven’t gone into pivot polishing or re-bushing as you just wanted to know how polishing was achieved. Clock makers have their own ways of doing things. This is what I was taught by my master and it is an old fashioned way.

[HectorLooi]

Thanks, @oldhippy.

That must take a few days to complete a whole clock.

What's your opinion on Renaissance wax. Have you ever used it?

Would you apply lacquer or varnish to the plates to preserve the shine or is French chalk enough?

[MikeEll]

hmmm, I'm not so sure.  The price seems high for a basic clean overhaul, but I dont see it necessary to do a full museum-quality restoration on the movement unless thats what the customer has asked for. I certainly wouldnt be re-blueing screws in a basic service, especially for a movement thats likely to be hidden in a case.  But, it should be clean and well-lubricated.

Totally depends on the client and what they want I suppose.

Edited March 21 by MikeEll

[watchweasol]

I have done several of these clocks and as @oldhippy says the prime mover is elbow grease. Plates polished with brasso and in my case very fine wire wool as the brass was almost black . I have seen plates look like that on professional y cleaned clocks , as dull as dishwater.  I don’t achieve as classic a finish as the example that @oldhippy showed but way better than the one you received. The price was a bit steep but he has overheads etc to pay for. It has taken me all day to clean some plates some times longer.

[oldhippy]

Renaissance wax. I never used it. But I know quite famous clock maker who uses it , so it must be good. 

I was not just a clock repair but most of my work was restoring which means getting the clock to its originality I worked on high grade clocks, but I had to cut my teeth on cheap movements.  

[mhamilton]

This makes sense. Prices are higher because everything is expensive in my city (you can't even get a cheap lunch for less than $25 these days). But this is probably the level of finish provided based on what their customers want. 99.9% of their clients don't know or care what the inside of the clock looks like, so as long as it's functionally cleaned and serviced they are not going to spend time on internal cosmetics. Most of the old clocks in this area are early-to-mid 20th century American clocks, cuckoo and grandfather clocks, he even commented to me that this style of French clock is very rare to see here, maybe he didn't know the best way to do this work. This shop is also slammed with work--as they are not going to take extra time, unless as watchweasol said, the customer requested it. I did not request anything specific beyond the functional service. 

The one thing I will not excuse is if he didn't service this rate adjuster correctly. I had made a point of mentioning when I dropped off the clock that the front adjuster did not ever work properly. So there's no excuse for why that should have been left in poor repair. I will pull that out this weekend and post back.

Side question--on the topic of the badly tarnished brass, the front and rear bezels are also similarly tarnished and very dark. The innermost bezel around the dial appears to be gold plated? You can see I tried a little cleaning/polishing on the outer bezel but did not go too far. Would this entire bezel have been gold plated originally? Or was it always brass and just needs a proper cleaning?

[oldhippy]

It would be polished and then lacquered. 

 

[watchweasol]

As @oldhippy said polished and lacquered, yours is going to need a bit of work, brasso fine wire wioll 0000 grade and a bit of elbow grease, but once done will enhance the. Visual impact of the clock no end, don’t forget the rear door will need cleaning , most are just dark metal but the doesn’t mean it’s left dirty.