Frodsham 84 Strand -- modified movement?

[John Matthews]

jplotkin - excellent videos - many thanks for posting

A wide shallow fork like that might have been working with a triangular roller jewel. If that were broken then, given the unlikelyhood of finding a spare, I can imagine a later repairer replacing the roller with a more common round jewel single roller.

Seth - the triangular jewels used in the C19th single rollers, I have seen photographs of (I have never handled one), appear to have been set into the roller in a triangular or rectangular slot, with the width usually greater than the diameter of a standard cylindrical jewel. Also, the shape of the mouth of the fork is significantly wider than the depth (sorry if I have used the wrong descriptors). As a result I am not convinced, that this roller and lever were originally designed with a triangular impulse jewel.

You will have seen many more than me and probably handled some, so I'm more than happy to be corrected. Do you have a photograph you can post?

John

 

[SKennedy]

Here's a triangular roller I had last year but I've not got a photo of its lever. Also a keyless Frodsham/Nicole movement. I'll have a look further back in my photos when I've more time.

As you say its in a triangular hole but you could have one that is not very much wider than a round jewel would be. My suggestion is that, if the escapement has been altered in this watch, that the complete roller with its round jewel was swapped in but the lever left in place. It works but the round jewel would inevitably be smaller diameter that the fork would allow as Graham is suggesting appears to be the case.

Joshua, a shame you didn't take the dial off so we could see the rest of the winding! But I think it is possible to see an arbor running through between the plates as I had suggested.

My suggestion is that, if the escapement has been altered in this watch that the complete roller with its round jewel was swapped in but the lever left in place.

 

[jplotkin]

Joshua, a shame you didn't take the dial off so we could see the rest of the winding! But I think it is possible to see an arbor running through between the plates as I had suggested.

Yeah, sorry. I tried to get photos from the side that would show any arbor, and I can see one. (I can post more shots).

The difficulty is that I love this Frankenstein, it has a neat display case, and I'm too timid to mess about with a fusee, at this stage.

 

[John Matthews]

Seth - thanks for posting the roller, pity you don't have a photograph of the lever.

The forks that I recall are similar to those associated with the dovetail jewel, as favoured by Barrauds and Vulliamy. They all seem to have a characteristic shape to accommodate the tapering sides of the jewel

Personally, I don't think the escapement is original.

John

 

[gmorse]

Hi jplotkin,

Here is the slow-motion video in zipped .mov format; seems to show guard pin away from roller. Also, the fork is quite still at all times except for during impulse.

Thanks for posting this video. It certainly shows that the guard pin is staying away from the roller as it should. However, the transition from unlocking, when the impulse pin moves the lever, to impulse, when the lever gives the impulse pin a kick, involves the pin's contact with the fork jumping from one side to the other. This happens very rapidly, from the waveforms it seems to take around 6 or 8 milliseconds, but the total time from unlock to drop is different on the two pallets, varying from ~12 to ~19 milliseconds, which suggests that the drops at least are uneven. It's possible to see four noise peaks on one pallet but only three on the other, see attachment. This may possibly indicate uneven banking or even a chipped pallet jewel, but only a minute examination can confirm whether this is the case.



The detection of an extra peak isn't always clear, but the left-hand event is some 6 milliseconds longer than the right and does consist of four discrete peaks. The software ignores the impulse peak as it's not of much use in timing. (Don't worry about the odd traces on the tape, I was playing with something there!).

I'd be interested to hear Seth's opinion of this image.

Regards,

Graham

 

[John Matthews]

the total time from unlock to drop is different on the two pallets, varying from ~12 to ~19 milliseconds, which suggests that the drops at least are uneven

Graham I also note that on the shorter cycle the impulse peak is much higher - does that equate to greater force being given to that pallet and therefore you might expect the cycle to be shorter. If that is correct, could the differences in impulse be due to how the one pallet is is engaging with the escape wheel, which you say might be due to a chip, but could it also be due to the orientation of the pallet, with respect to the escape teeth?

John

 

[gmorse]

Hi John,

...but could it also be due to the orientation of the pallet, with respect to the escape teeth?

Not so much with respect to the escape teeth but more to the lever fork, which determines where the pallets are when unlock happens. If the lever and pallets were originally made to match the escapement in a different watch, and there is some suspicion that it could be the case here, it would give rise to these sounds.

Regards,

Graham

 

[SKennedy]

Seth - thanks for posting the roller, pity you don't have a photograph of the lever.

The forks that I recall are similar to those associated with the dovetail jewel, as favoured by Barrauds and Vulliamy. They all seem to have a characteristic shape to accommodate the tapering sides of the jewel

We're probably drifting off at a tangent now but I've found I have photos (taken a couple of years ago) of two early Nicole chronographs with triangular jewels and conventional lever forks. Here's one.

Graham, while I have the same software, being a bit of a technophobe* I only scratch the surface of its capabilities so you probably get far more out of it than I.


*My wife looks after all of the technology at home phones, computing etc, to the extent there are lights I can no longer turn on and off....

 

[gmorse]

Hi Seth,

...while I have the same software, being a bit of a technophobe* I only scratch the surface of its capabilities so you probably get far more out of it than I.

I don't suppose I know much more than you do, it's an extremely comprehensive and sophisticated piece of software, (and I only have the demo version!). What it does is to give a very complete picture of how the escapement is behaving, I just need to learn to interpret what it's telling me!

Regards,

Graham

 

[John Matthews]

Nicole chronographs with triangular jewels and conventional lever forks

Seth - Many thanks for posting these photographs - added to my knowledge.

John

 

[jplotkin]

Hi All,

So here is a detailed follow-up. Starting with photos of the impulse jewel and lever, when the balance is at rest. The impulse jewel does not appear dramatically too small for the fork -- it fits in the fork pretty snugly. (Some debris is apparent -- which led me to disassemble and clean).

Your comments inspired me to decase, clean, and document the escapement more thoroughly.

Here's the impulse jewel (before cleaning up). It actually has a slight D-shape, as opposed to a strict cylinder:

Here is the lever itself:

Neither pallet jewel appears to be chipped (photos before cleaning up some debris):

Nothing seems horribly wrong with the pallet/escape interface:

And now the endstones are all cleaned and oiled, including diamond. Pallet jewels treated to a bit of Moebius 941, as well.

Payoff for all that inspection and cleaning? Same low amplitude and low rate!!

But I don't see anything obviously wrong with the escapement parts, do you? Perhaps the original triangular jewel was replaced with this D-shaped one. But the sizing looks still OK to an untrained eye. Finally, here a new audio recording of the movement in action after re-assembly -- I'm sorta eager to see if any of the cleaning has resolved four distinct peaks on both pallets, and asymmetry in the duration from drop to unlock, across the two pallets.

 

[gmorse]

Hi Joshua,

Finally, here a new audio recording of the movement in action after re-assembly -- I'm sorta eager to see if any of the cleaning has resolved four distinct peaks on both pallets, and asymmetry in the duration from drop to unlock, across the two pallets.

The new pictures are most helpful. The jewel is indeed a D shape, which suggests that it may not be original, and it does fit the lever fork pretty closely as far as I can tell, although the fork is comparatively shallow, so at any rate that theory is now dead. If the pin was indeed originally triangular, then I think Seth is right that the whole roller must have been replaced at the same time, since there's no sign of the present hole being able to take the triangular shape.

The pallets look undamaged and apart from some pre-cleaning debris, (which looks like fragments of shellac), it all seems in reasonable order.

The cleaning seems to have tidied up the uneven noises:

Frodsham Recording 2 mono.wav

The next step to address the slow running is to count the fourth wheel and the escape pinion, because the fourth wheel must rotate once per minute, so you can arrive at the proper beat rate for the balance from that. If it is in fact 16,000bph, I notice that the two meantime screws at the ends of the balance crossings have been wound out, which will slow it down, and you could try screwing them both in, but do be very careful not to bend the balance rim, and they must each go in by the same amount.

Regards,

Graham

 

[jplotkin]

Graham, Thanks for audio analysis.

I think you mean 16,800 bph = 280 bpm is your best guess. So can you help me with my (first-timer) math here?

On the escape wheel I count 16 teeth and 8 leaves in the pinion, for sure. It's harder to see the 4th wheel, but I count somewhere between z=66 and z=72 teeth on the 4th wheel.

If there are two beats per escape tooth (one for each pallet), then I get 2*16/8 = 4 beats per escape pinion leaf. In one minute, the escape pinion advances z leaves (one pinion leaf per tooth on the 4th wheel). And so there are 4z beats per minute. If z=70 (which seems reasonable, given my image of the 4th wheel), this gives 280 bpm, which matches your guess of 16,800 bph. Is this math correct?

Anyways, in order to tighten the meantime screws on each end of the balance arm, I presume you recommend removing the hairspring, and somehow fixing the wheel? Seems tricky, but not impossible. How much do you reckon I tighten (two full turns?) given that it’s running 500s/day slow?

 

[gmorse]

Hi Joshua,

I was basing the figure of 16,800 on your observation that it's running about 300 seconds per day slow. Since the actual rate is around 16,730, this implies that the correct rate is indeed 16,800, thus the eTimer screen shows a losing rate of 356.2 seconds per day.

Escape wheels usually have an odd number of teeth, but I'm pretty certain that yours does indeed have 16. If the 4th wheel has 70 teeth and rotates at 1 rpm, the escape wheel with its pinion of 8 rotates at 8.75 rpm, so working backwards from the supposed correct rate, 70 times 16 over 8 should equal 140, which it does; because there are two pallets, the beat rate is twice 140, or at least it should be.

I think on consideration, not withstanding what I suggested earlier, that if you aren't familiar with working on balance wheels at this level, you would be well advised to put this work out to a competent watchmaker. This is too good a watch to risk any damage to the balance, because it's so easily done!

Regards,

Graham

 

[John Matthews]

Joshua - thank-you for continuing to post excellent photographs of this escapement.

I have limited experience, compared with Graham and Seth, all I can do is to compare this single roller escapement with those I have in my collection.

Having just made the comparison with ~20 examples, this roller and the fork of the lever are, in detail, unlike any I have seen. My observation is that to me both appear to have been modified in order to make them work together. The impulse jewel is positioned closer to the small passing arc, than any other examples I have seen.



To me the throat of the lever fork appears to have been enlarged to accommodate a wider jewel.



and the safety pin appears to have had material removed to give the necessary clearance clearance with the roller.



John

 

[Chris Radek]

Several of your (very good) photos, especially that last one, clearly show that the pallets are too low or the roller is too high. The jewel is just barely in the slot. The pallet arbor looks totally bogus in #61, with one pivot 4x as long as the other? Someone has made a replacement arbor and didn't get it right. The arbor is a taper, and the pallets need to fit with the right tightness at the right height on it. It's not as simple a part as it appears.

To make the appropriate fix one needs to consider all the heights and clearances in the escapement, from escape wheel to balance. I would guess that just the pallets are wrong, and it needs only the one part remade, but all the things must be checked before starting.

Frankly I would stop running it, because poor height (and depth) matching from pallets to escape wheel can very easily eat the tips of the teeth and then you have a real mess. I promise nobody has a stock of 16 tooth escape wheels waiting to be swapped in there!

Here is a photo from a very similar job, the new part installed in the pallets (this M.I.Tobias did not have cap jewels on the pallets like yours does, so the shoulders are square.) You can see the old one from a botched repair behind, with shoulders that are not square, and a mangled taper where someone tried to adjust the height.

 

[jplotkin]

Thank you, Graham and John.

I am happy to have verified that the escapement appears in good order — and I agree it appears to be carefully modified to accommodate the D shape jewel (although, the safety pin has no material shaved off; the image was just out-of-focus there).

I’m supremely pleased to have achieved such a symmetric sound profile across both pallets, by cleaning!

This success gave me some confidence to consider meantime screw adjustment. But you’re probably right, Graham, it’s too great a risk in my hands at this stage. So I’ll just accept the 300s/day slow rate. I can wind and set each morning, and enjoy the display case all day long.

Thanks again for your insights.

 

[jplotkin]

Argh, I just saw Chris’ post...

Yes, I noticed that the impulse jewel is just barely low-enough to contact the fork. Seems not ideal.

I also noticed that the pivots on the pallet are very different lengths up vs down. But I don’t see why this would be a problem. Is it?

The pallet jewels seem to be at the correct height relative to the escape teeth (there is no metal-on-metal contact). I don't think I have a graph photograph showing this; but one image is below. If so, I see no danger in running the movement...

 

[Chris Radek]

Aside from being poor workmanship, the mismatch of the pivots isn't really a problem in itself.

But this is like if you're looking at a used car and each of the doors and body panels are painted a different color. I mean colors don't really affect the driveability, but it should make you wonder about the history of the car, and would make you look closer for related problems.

In your watch's case, it just means this part has been badly remade, and we see other signs that it's wrong (a height problem), so it's a smoking gun.

 

[Chris Radek]

I think another image appeared after I posted last! If the center of the pallet jewels and the center of the teeth are the same height (you'd need to look side-on to confirm, and also check their endshakes) , then either they are both at the same wrong height, or the roller is at the wrong height.

In this photo it looks like the escape wheel tooth may be touching the flat part of the pallets, and it should not be able to do that, even if you push the pallets up and the wheel down (taking up endshake in opposite directions.)

 

[jplotkin]

I believe the escape teeth and pallet jewels are at the correct height relative.

In this photo it looks like the escape wheel tooth may be touching the flat part of the pallets, and it should not be able to do that, even if you push the pallets up and the wheel down (taking up endshake in opposite directions.)

I don't entirely understand what you mean by "escape wheel tooth may be touching the flat part of pallets." In image #68 above, I believe the escape wheel tooth is touching the locking face (dead face) of the entry pallet jewel. The steel of the pallet fork itself is shiny and so you can see a reflection of the gold escape tooth there, but it's not touching.

I don't have any good photos from the side, sadly. But at least I do have a poor-quality image extracted from a video, from the exit side, which seems to verify proper relative height of escape teeth and pallet jewels:

 

[gmorse]

Hi Joshua,

But at least I do have a poor-quality image extracted from a video, from the exit side, which seems to verify proper relative height of escape teeth and pallet jewels

I think it's clearly a given that this movement has been modified in various ways, although some of the details remain obscure. The escape teeth do indeed appear to be level with the pallet jewels, which are curved on their impulse planes in the usual way. As long as the inner sides of the lever fork are long enough to engage on the full diameter of the impulse jewel for the whole of their contact, there should be no problem with the action, and of course the base of the fork should never touch the jewel. There is some distortion at the base of the fork where the pin is set, which may be evidence of a replacement; that would not have been acceptable when it was made.

The lever arbor does look like a replacement, with that very long lower pivot, but it's impossible to be sure just from pictures how close the shakes are, particularly the sideshakes. Excessive sideways movement here can rob impulse from the balance, resulting in poor amplitude.

In escapements with triangular impulse jewels, the inner surfaces on the lever fork sometimes show uneven wear caused by the sharp corners of the jewel, which is one reason that this type was eventually abandoned, apart from the inferior geometry of its action.

Regards,

Graham

 

[jplotkin]

Graham,

Here's a video that shows the effective sideshake in the lever's upper pivot (which is capped).

The video is taken while the movement is running. You can see that the pivot really is moving from side to side within its hole jewel, instead of only rotating (although the lever motion rotates only about 30 degrees or so each beat). It almost appears is if the hole jewel is too wide.

Anyways, your thoughts on what this reveals about the level side-ways endshake would be interesting to me.

Thanks.

 

[gmorse]

Hi Joshua,

It almost appears is if the hole jewel is too wide.

The pivot is moving sideways by about 1/3 of its diameter, and since it's a replacement arbor, it isn't that the jewel is too large, but the pivot was made too small. I know it's probably less than 0.2 mm in diameter, but it will be contributing to the loss of impulse. The remedy is to replace the arbor with one that's a better fit in the jewels.

It also looks as though the top balance staff pivot has a flattened tip, so the lower one probably has as well, and this will have an influence on the amplitude in horizontal positions.

Regards,

Graham

 

[jplotkin]

Thanks, Graham...much more of this and I'll find a lathe on my desk. Watchmaker's work is never done, it appears. (But I'm still happy with the movement as it is, even with the occult history of modifications it has endured.)

This Frodsham has given me all the more appreciation for this free-sprung Preston/Dent movement, which produced tremendous amplitude and +2s/day after a simple cleaning.