Dent free-sprung movement, 61 Strand Street LONDON

[jplotkin]

Hi All,

I recently picked up this Dent movement, likely dating between 1901 and 1910. It has a free sprung balance, diamond balance jewel, and it appears completely unmolested.

The pallet fork seems to have a metal pallets that interact with the pointed escape wheel, instead of jewels for pallets (see photos). Is that typical of these English movements?

Also, I can't figure out how to wind it! The pendent presumably had a gear that interacts with the exposed ratchet wheel. Advancing the ratchet wheel with brass tweezers clicks the click, but it doesn't wind the mainspring. Am I missing something?

Putting pressure on the barrel results in proper movement, but I just can't wind the MS.

Any thoughts on the movement, the pallet, and winding would be really appreciated, thanks!

 

[gmorse]

Hi jplotkin,

The pallet fork seems to have a metal pallets that interact with the pointed escape wheel, instead of jewels for pallets (see photos). Is that typical of these English movements?

The pallets are jewelled, but in the English style, which mounts the jewels in horizontal slots rather than vertically, which is why you can't easily see them until you take them out of the movement. The ratchet tooth escape wheel is another English feature, with all the lift on the pallets, in contrast to the club tooth lever which divides the lift between the teeth and the pallets.

The pendent presumably had a gear that interacts with the exposed ratchet wheel.

Yes, the stem would have had a bevel gear to engage with that winding wheel. It will be very hard to wind it out of the case!

This is a good quality watch from a very famous maker, which would almost certainly have been housed in a gold case from one of the top London makers.

Regards,

Graham

 

[jplotkin]

Thanks very much for the information, Graham. Nice to understand how the pallets can be jewels, despite being unable to see this from above.

I still have one other question. I would really like to try to wind the spring, even a tiny bit, to test before opening the entire movement. It would be great to figure out how to do this. Rotating the winding wheel counter-clockwise with tweezers (viewed from above the movement, in the photograph) engages the click, and I hear it click as I rotate it, but this does not seem to wind the spring. Whereas trying to rotate the winding wheel clockwise is met with stiff resistance, presumably from the click.

Rotating the exposed barrel clockwise with tweezers (again, viewed from above the movement, as in photograph) drives the movement. I presume it's a "going barrel"?

Can you figure out how it might be possible for me to wind the movement, even just a bit, without having the stem/case/bevel gear?

 

[gmorse]

Hi jplotkin,

The resistance you feel is the power of the spring, but you must consider whether the mainspring may be fully wound already and something else is stopping it from running, which means you're going to have to let down the spring before doing anything else, just to be safe. Letting it down could be awkward as well, and I suggest that you remove the dial and see what the other end of the barrel arbor is like; there may be a square which you can grip securely with a pin vice. The click should be sitting under the barrel between the plates. If you can hear the click in one direction, that's the opposite direction to winding. That barrel houses a pretty substantial spring, and I can't see a safe way of winding it without the stem. You're right about it being a going barrel, and I suspect, from the steel collar around the barrel arbor square showing on the top plate, (first picture) that it has Geneva stop-work hidden under there, and that collar is the top of the finger-piece. If it has, remember that the spring will be under some tension even when you take out the barrel.



By the way, because the fourth wheel is under a separate cock, this is technically a half-plate movement.

Regards,

Graham

 

[jplotkin]

As usual, you were entirely correct Graham. The barrel has Geneva stopwork, and the pallet jewels are mounted as described. See my photos:




But the mainspring appears to be completely unwound -- it was not providing any pressure on the center arbor, at least.

My only remaining issue is how to remove the dial (!). There are no dial screws in the side of the movement. I think the dial is maybe attached via two of these unusual fasteners (pins through the pillar plate, secured with brass fasteners on the movement side of pillar plate), one pictured here. Do you think these pins are securing the dial onto the pillar plate? Should I try to drive out the brass fasteners?



Thanks for your continued advice. It's a truly lovely movement.

(Note feel free to move to PW repair if desired).

 

[roughbarked]

The dial is secured by the pins through the dial feet. Remove the pins and the dial will come off easily.

 

[gmorse]

Hi jplotkin,

roughbarked is perfectly correct, this was the standard method of securing dials on English watches for centuries. Be careful when removing the pins because the posts are copper and hence quite soft, soldered to the copper substrate of the enamel dial.

Out of interest, what does the barrel click look like?

Regards,

Graham

 

[jplotkin]

Thank you both.

Yeah, I think I’ll add a little penetrating oil before trying to push the pin through the hole in the dial feet. The pins are pretty well stuck right now, and I don't want to damage the dial feet.

I will show you the click as soon as I get the dial off. In the meantime here at least is a wide shot of the pillar plate from movement side:

 

[John Matthews]

Jplotkin - just to be sure, you said 'push' the pin through the hole, this might just be the way you are describing the process, but I hope you mean to extract the pins outwards away from the movement.

John

 

[roughbarked]

I was taught to push the pins out from the back rather than pull them out.

 

[John Matthews]

I was taught to push the pins out from the back rather than pull them out.

Yes - but given the pins were proving difficult to remove, I was just wanted to make absolutely sure that attempts had been made to extract the pins in the correct direction.

John

 

[gmorse]

Hi jplotkin,

The method you use depends in part what sort of access you have to the pins and how much of the thinner end is poking through the post. Sometimes some slotted pliers like this are useful, and sometimes a pair of side cutters, (not to cut the pins off!), will provide a better grip than smooth jaws if you have to pull rather than push.



Oh, and it's good practice not to re-use the pins you extract, but install new ones on reassembly.

Another thing to be aware of regarding the barrel; if you remove the barrel lid, it's important to put it back in the right orientation. The picture shows an extra cut out in the edge which has to align with a tiny pin in the barrel wall, whose purpose is to prevent the lid rotating under the pressure of the stop work. If this isn't done, the lid won't seat properly, the cut out and/or the pin can become damaged and the lid can end up rotating and may eventually pop off. This only applies when the stop work is in the lid.



Regards,

Graham

 

[jplotkin]

Thank you all for your continued attention -- it's tremendous.

I have not yet done it, but I was intending to push the pins through the dial feet, away from the movement. After removing pins, I will just push the dial feet themselves down through the pillar plate. Diagram here:

I don't have any fancy tools for this. I hope that flat nose pliers will be sufficient for pushing. I will add some oil at pin/dial-foot interface to lubricate.

Thanks also, Graham, for the note about the barrel -- I was wondering about the purpose of that extra pin in the barrel. I don't plan to open the barrel lid. And I understand that there might still be some pressure on the spring because of the Geneva stopwork -- so I will hold the backside of barrel arbor in a vice, as you suggest, while removing the Geneva stopwork from the top of the lid, in order to control any further let-down. (But I don't entirely understand why that pressure wasn't being transferred to the center arbor of the movement.)

 

[gmorse]

Hi jplotkin,

(But I don't entirely understand why that pressure wasn't being transferred to the center arbor of the movement.)

The barrel is stopped from trying to revolve by the stop work when it's run down, in that state the only pressure is between the barrel arbor, or more precisely the finger piece squared onto it, and the Maltese Cross piece fitted into the barrel lid. To let that down, if you have the other end of the arbor secured in a pin vice, turning the barrel slightly in the winding direction will enable you to lift the finger piece off the square and let the rest of the spring tension off; it should be about one turn. Then you can take the lid off to look at the spring even if you don't want to remove it from the barrel.

Regards,

Graham

 

[jplotkin]

Graham,

As requested, here are some photos of the click, from the bottom of the pillar plate. Note that the square peg on the bottom of the barrel seems to have a pin running through it to keep in place. I guess I'll have to remove that.

I also included a photo of the cannon pinion. Is this a normal American style friction fit cannon pinion?

 

[John Matthews]

The marking on the plate contain the initials J.P -



This is the mark that is often ascribed to a Lancashire movement maker Joseph Preston. You may wish to look at this thread.

The initials are found in a number of variants including JP, J.P & J·P. To my knowledge there has been no rigorous research to identify the significance of the various stamps and to relate them to specific date ranges, based upon authenticated dates of manufacture. This would be an interesting area of research, for anyone able to dedicate the effort that it would require. In a recent publication, Jonathon Betts, inferred that J·P was an earlier mark and J.P later.

It is probably that this frame was made by Joseph Preston & Sons operating from Eccleston Street in Prescot.

John

 

[jplotkin]

Thanks, John. I was wondering about those initials. And I note that the number there on the pillar plate is different from the Dent serial number on the movement top plate (seen in post below). We can be sure the movement was completed between 1901 and 1910 ("maker to the King"), but perhaps the pillar plate was made earlier by Joseph Preston, or contemporaneously by his offspring (Preston & Sons)?

 

[jplotkin]

Serial number on movement:

 

[gmorse]

Hi jplotkin,

Thanks for the pictures. What you show is typical English work of the period, and you will have to remove that cross pin in the barrel arbor to take the ratchet wheel off. The cannon pinion also looks typical as far as I can tell; they're quite substantial, having quite thick walls and usually fairly well hardened, so their friction on the centre arbor can't be altered by squeezing the sides, as it can with many other types. (I don't think this has a hollow centre arbor but I may be wrong. If it has, the cannon pinion will be a tight fit on the central pin and friction between the pin the inside of the hollow arbor will allow for hand setting).

The level of finishing which frame and movement makers produced on their creations did vary, depending on the requirements of those such as Dent who they supplied. There were 30 or so specialist trades involved with the making of 'raw' movements, and probably as many again in the finishing when they reached the likes of Dent or Frodsham.

Regards,

Graham

 

[jplotkin]

Graham,

Could you please help me figure out how to remove the barrel lid?

I have removed the Maltese Cross, and completely unwind the spring (it had about 1.5 winds left in it). But i don't understand how to remove the lid. The "finger" portion of the stopwork seems firmly attached to the square arbor, and I can’t seem to pry it off.

Should I try to pry the entire lid with the finger still attached to the arbor? That seems like a bad idea... But I don't know how to remove the finger -- I expected it to fall out once removing all MS tension.

Thanks again for your advice.

 

[gmorse]

Hi jplotkin,

Could you please help me figure out how to remove the barrel lid?

I expect the finger piece is just stuck there with old oil, because it simply fits on the barrel arbor square; it may be a snug fit but there's nothing else holding it on. Try soaking the whole barrel in whatever solvent you have handy, naphtha, (Coleman fuel), would be a good start, or if you have some penetrating oil. Be careful if you're trying to prise it off, because these parts were usually left quite hard, and it's possible to snap off the finger. Apply the levers on both sides if you can, otherwise the piece can bind.

I guess you could remove the lid still attached to the arbor, but that shouldn't be necessary.

Regards,

Graham

 

[SKennedy]

There is a small possibility that the finger piece does have a cross pin holding it on to the arbor. Unlikely and it'll be obvious to see if its there.

I guess you could remove the lid still attached to the arbor, but that shouldn't be necessary.

I've done that occasionally if the stop work finger won't move easily. You've just got to be careful that the spring arbor is detached from the centre of the mainspring as you lift it. But with the lid off the barrel it is then much easier to knock the arbor through and also means there's no risk of damaging the finger piece or marking the barrel lid while trying to lever it off.

 

[gmorse]

Hi Seth,

There is a small possibility that the finger piece does have a cross pin holding it on to the arbor. Unlikely and it'll be obvious to see if its there.

With this design, in which the upper part of the finger piece forms the bearing surface in the top plate, I agree with you that a cross pin is highly unlikely.

Regards,

Graham

 

[jplotkin]

Thanks again. I will soak entire barrel in Naptha, and then try to loosen finger from arbor. There is no cross pin.

As for prying off the lid, do you suggest just a small screwdriver through the opening on one side or the other (these are rounded openings, as opposed to rectangular openings in American Pocket watches, but perhaps a small screwdriver will work for prying. Or should I pry from both sides of lid simultaneously?)

 

[gmorse]

Hi jplotkin,

but perhaps a small screwdriver will work for prying. Or should I pry from both sides of lid simultaneously?

Both sides is best, but a small screwdriver is fine if you have one that doesn't matter too much, (using a good one isn't recommended). Do it gently and the lid should just unsnap. You can see where one has been used before from the slight marks in the barrel lip.

Regards,

Graham

 

[roughbarked]

nice word, unsnap.

 

[jplotkin]

Thanks yet again. Everything went smoothly, as you suggested Graham.

I'm happy to report that the watch is now completely clean and mostly re-assembled. Here is a glamour shot of the keyless works:






One final question, though (and at that point I'll probably have to send you the movement when it's done -- you've earned it). How do you suggest removing the hairspring stud from balance cock on these free-sprung movements? The difficulty (compared to American) is that the screw holding hairspring is on top of the cock, as opposed to the side. So I don't know how to position the cock while removing this screw.



Should I put the balance back in the movement and risk pressure downwards on the balance shaft while unscrewing stud? Or hold the whole cock free, upside down, and try to unscrew the stud from below? Screw seems tight. But I won't be happy until I can clean the diamond cap stone!

Also: do you oil pallet stones in these English style movements with ratchet tooth escape wheels?

 

[gmorse]

Hi jplotkin,

How do you suggest removing the hairspring stud from balance cock on these free-sprung movements? The difficulty (compared to American) is that the screw holding hairspring is on top of the cock, as opposed to the side. So I don't know how to position the cock while removing this screw.

I'd take that screw out with the balance and cock in the movement. That way, the balance and spring are safe. If you have the right sized screwdriver to fit it properly you shouldn't have to press down too hard and once it's removed the stud will just slide forwards a bit and you can take the balance cock off, leaving the balance behind. In fact, I think the screw hole in this stud is open at the side so you won't have to remove the screw completely. This type of stud was common on most English watches, not just the free-sprung ones.

Also: do you oil pallet stones in these English style movements with ratchet tooth escape wheels?

Yes, just a little Moebius 9415.

I notice from your picture that the raw movement was made by Joseph Preston in Prescot, who was one of the best movement makers of the period, supplying movements to almost all of the top London houses.

Regards,

Graham

 

[jplotkin]

Just a quick note to say thanks again to Graham and others for all your advice and historical insights. The DENT movement is now purring.

It is maybe the finest movement I own from this time period -- better in many ways than an E. Howard & Co N size movement, for example. Many detail of the finishing are impeccable, such as the polished bevels around the pallet, the placement of the pallet stones in the lever, the cut cap stone on the balance. And it immediately gave me 270 degrees of amplitude and +2s/d without regulation (free sprung balance), without even replacing the steel spring.

Quite a timepiece.

I'm attaching a short video of the movement in action, as a zip file. Thanks again.

 

[gmorse]

Hi jplotkin,

Many detail of the finishing are impeccable, such as the polished bevels around the pallet, the placement of the pallet stones in the lever, the cut cap stone on the balance. And it immediately gave me 270 degrees of amplitude and +2s/d without regulation (free sprung balance), without even replacing the steel spring.

The closer you look at watches of this quality, the more you appreciate the superb craftsmanship of the people who made them. They're a real pleasure to work on. Remember that freesprung watches were the pinnacle of the trade and were always expensive. Also, without a regulator, the owners had less to tinker with and upset the adjuster's good work!

Out of interest, how did you manage to wind it?

Regards,

Graham

 

[jplotkin]

I prefer to keep the dial off, so I can view the terrific keyless works.

I wound it by directly advancing the ratchet wheel (see picture) with a screwdriver applied to the wheel's teeth, while the movement is held fixed. I advance the ratchet wheel 1-2 clicks at a time, moving it about 6 clicks before removing the screwdriver and re-applying it to a different tooth on the ratchet wheel. It was a tedious but seemingly controlled procedure.

It is also possible to wind by advancing the exposed crown wheel (again, with a screwdriver blade applied between teeth), which transfers the motion to the ratchet via an intermediary transfer wheel. But for some reason this method of winding is difficult -- it requires much more pressure, and the wheels advance in "bursts" of about 3-5 clicks at a time, which feels uncontrolled.

Is it unadvisable to be applying pressure to the ratchet wheel teeth directly in this way, for occasional winding?

 

[Dr. Jon]

The issue is scratching it. I do this with a pegwood stick and I am careful to remove any widd that get into the teeth.

 

[gmorse]

Hi jplotkin,

Is it unadvisable to be applying pressure to the ratchet wheel teeth directly in this way, for occasional winding?

I wouldn't wind any wheel with a screwdriver in this way; you risk breaking a tooth because these wheels are usually left fairly hard, and it's also not good for the screwdriver. If you have no alternative to turning the ratchet wheel, (which is squared onto the barrel arbor), in order to test the watch, then a tool like this with two pins is a little safer.



It does at least use two pins which engage on a diameter, so the risk of breaking a tooth is reduced.

Winding by turning the crown wheel directly will be harder because the transfer wheel is smaller, (looks like 2:1), and when cased, the ratio of the stem pinion to the crown wheel would be much larger in the opposite sense, possibly 1:4 or more, which would offer a greater mechanical advantage.

Regards,

Graham

 

[jplotkin]

Thanks. Yeah, I was worried about winding in that way.

What if I use (soft) brass tweezer to advance the ratchet wheel, applying the tweezers to a single tooth (or perhaps two diametrically opposed teeth, if tweezer can be spread enough) -- is that still too risky?

And what is the name of that two-pin tool (with adjustable diameter, I presume, and with pins flattened on one side each)?

Out of interest: why is riskier to apply a screwdriver, whereas there would be little risk of breaking a tooth if I had possession of the case/stem pinion? Does a stem pinion actively engage multiple teeth (of the crown wheel) simultaneously?

 

[sternerp]

Hi Graham!

In your second comments it can be seen a barrell with 2 maltese cross "nest". I have also one movement with so solution. If you can upload here some photos from this movement, please do it (I collect these, there are already some examples.)
I don't know that does have any function or conscious design. Earlier i had a such question here on the forum.

Regards! Peter

 

[gmorse]

Hi Peter,

I don't know that does have any function or conscious design

That extra recess was, I believe, the result of an earlier repair that either went wrong or was later removed. As received, it was evident that the recess I used was the original one because it has traces of gilding. Since the boss was missing I had to make the retaining screw for the Maltese Cross piece with a shoulder. The other barrel in this watch had that screw broken off, so perhaps this extra recess was made rather than extracting the screw.



Regards,

Graham

 

[jplotkin]

Thanks. Yeah, I was worried about winding in that way.

What if I use (soft) brass tweezer to advance the ratchet wheel, applying the tweezers to a single tooth (or perhaps two diametrically opposed teeth, if tweezer can be spread enough) -- is that still too risky?

And what is the name of that two-pin tool (with adjustable diameter, I presume, and with pins flattened on one side each)?

Out of interest: why is riskier to apply a screwdriver, whereas there would be little risk of breaking a tooth if I had possession of the case/stem pinion? Does a stem pinion actively engage multiple teeth (of the crown wheel) simultaneously?

 

[gmorse]

H jplotkin,

What if I use (soft) brass tweezer to advance the ratchet wheel, applying the tweezers to a single tooth (or perhaps two diametrically opposed teeth, if tweezer can be spread enough) -- is that still too risky?

And what is the name of that two-pin tool (with adjustable diameter, I presume, and with pins flattened on one side each)?

Out of interest: why is riskier to apply a screwdriver, whereas there would be little risk of breaking a tooth if I had possession of the case/stem pinion? Does a stem pinion actively engage multiple teeth (of the crown wheel) simultaneously?

The risk is that by inserting something between the teeth which could jam and force a tooth sideways, it could break it. Brass is certainly safer than steel, but still not recommended. Dr. Jon's suggestion of a wooden peg should be safe because the wood will break before the steel.

The tool is something that was made by a late watchmaker friend of mine and I don't know that it has a proper name; I suppose it's a sort of wrench. It has several uses, including unscrewing the nut on some transmission wheels, and also gripping the barrel ratchet to let down the spring on a fusee movement if the square is too short to grip safely.

The stem pinion is designed to mesh with the crown wheel and engage the individual teeth correctly, whereas a screwdriver could easily put pressure on the very tips of the teeth, which they aren't necessarily designed to withstand.

Regards,

Graham

 

[sternerp]

Hi Graham!
Thank you very much your reply, but i think that you will send picture from the movement also;-) If possible, i would thanks again!
Yes, my movement it also looks like, that a result of later repair.
But i wasn’t sure, because i have one picture in my collection that both maltese crosses is present (it’s true, that the stop finger part is not present!) That’s i thought, it might have had some function?
Peter

 

[gmorse]

Hi Peter,

The absence of the gilding under the left hand cross and in the centre on your example suggests that the recess on the left has indeed been added later, but I don't know why there should be two Maltese Cross pieces. There couldn't have been two fingers on the arbor, that wouldn't have worked at all!

The watch whose barrel I showed is with me for restoration, so I will ask the owner whether he will allow detailed views of the whole movement to be posted.

Regards,

Graham

 

[sternerp]

Hi Graham!

Really don’t need 2 Maltese crosses, as one does the job perfectly! And indeed in most cases the lack of gilding is visible, so it must have been made later. But here one movement, that all two maltese cross "nest" has gilding...
I didn't mean that the finger piece part has two fingers, but just one.
In this way it works well, but stops half a turn earlier (if set correctly)
If i think good?
It cannot be, that a shorter mainspring was placed in place of the broken one during the repair, and thus corrected it?
Can be stupid, just thinking ...

ps: there are some parts ... I played with it a bit ;-)

Regards! Peter

 

[gmorse]

Hi Peter,

You're lucky to have that stock of parts, I had to make the necessary parts from scratch.

If the owner does agree to the posting of some pictures, I suggest that you start a new thread for the subject rather than diverting this one from the OP's theme.

Regards,

Graham

 

[gmorse]

Hi Peter,

The owner is happy to see his watch illustrated here, and he agrees with me that a fresh thread dealing with some of your watches would be an appropriate vehicle for this.

Regards,

Graham

 

[jplotkin]

For anyone who is interested, a few more photos of this Dent/Preston movement.

And a group shot with some cross-pond comparison from the same era.

 

[gmorse]

Hi Joshua,

Very good pictures of the details in this movement. The 'tuning fork' lever tail is seen on some high-quality London work of the period, but I'm not sure that it has any practical function; it certainly isn't a resilient design as the two prongs are too thick to flex. I think the screwed on safety dart is gold.

The picture of the large diamond endstone shows traces of the brazing which holds the stone in the steel setting. This is usually more evident if you look at the underside. The balance spring appears to have a double overcoil. The double roller had by this time more or less replaced the single table roller, but the escape wheel is still the traditional English ratchet tooth type, with all the lift on the pallets.

The triangular Dent trademark was first used in 1876, supposedly in an attempt to deter counterfeiting, but it doesn't appear to have been particularly effective.

Regards,

Graham

 

[jplotkin]

Thanks, Graham.

The lever itself is really one of the hidden gems in the movement, to me -- especially the smoothed beveled edges.

Yes, the horizontal safety dart would provide functionality only in combination with a double roller balance assembly (whereas the movement has a single-roller). Perhaps this means the lever was made independently of the balance assembly, by a different craftsman, to provide that functionality if combined with a double-roller?

I'm including a close-up of the balance spring (is it really a double over-coil?), and the confirmed single roller.

Yes, the diamond end stone has some trace substance on its top surface, which I couldn't easily clean off. I'm showing two other pictures of the endstone from different angles -- one from beneath, before cleaning; and one from above, after cleaning.

 

[John Matthews]

Yes, the horizontal safety dart would provide functionality only in combination with a double roller balance assembly (whereas the movement has a single-roller). Perhaps this means the lever was made independently of the balance assembly, by a different craftsman, to provide that functionality if combined with a double-roller?

Joshua - I am a little confused, the escapement is a double roller ...



Your photograph shows the impulse jewel being supported by the large diameter of the roller next to the crossing, and the notch, which the safety dart engages with, is cut in the smaller diameter of the roller, closer to the pivot. With all 'true' double rollers the safety radius is smaller than the impulse radius. A double roller may be turned from a single piece of metal or the impulse roller and the safety roller may be made separately.

John

 

[gmorse]

Hi Joshua,

whereas the movement has a single-roller). Perhaps this means the lever was made independently of the balance assembly, by a different craftsman, to provide that functionality if combined with a double-roller?

I can see two rollers in your pictures, a small safety roller and the larger impulse roller underneath it. A single roller has the passing crescent cut into the edge of the roller next to the impulse jewel pin, whereas yours has no crescent. Perhaps a picture taken more from the side would make this clearer. Your lever couldn't work with a single roller because the safety dart overlaps with the fork.

[Edit] John just beat me to it!

Regards,

Graham

 

[jplotkin]

You’re right it is double! So the safety dart does have a function, right?

 

[gmorse]

Hi Joshua,

You’re right it is double! So the safety dart does have a function

Yes, the escapement wouldn't work properly without a safety function.

Regards,

Graham