Number of jewels represented as a fraction?

Thread: Number of jewels represented as a fraction?

1. Number of jewels represented as a fraction?

What does it mean when the number of jewels is represented as a fraction? Here's an example that describes the number of jewels as 1/17:
bidfun-db Archive: Watch Movements: Sonceboz ES 55

2. Re: Number of jewels represented as a fraction?

Originally Posted by Keith W
What does it mean when the number of jewels is represented as a fraction? Here's an example that describes the number of jewels as 1/17:
bidfun-db Archive: Watch Movements: Sonceboz ES 55
Looking at some other entries, it looks like it indicates the possible variants of the movement. On the ETA 2824 page, it is listed as 17/21/25 jewels.

3. Re: Number of jewels represented as a fraction?

Sure, but what the heck is a 1 jewel movement?

4.

5. Re: Number of jewels represented as a fraction?

Originally Posted by Keith W
Sure, but what the heck is a 1 jewel movement?
Not at all uncommon pin lever movements(which is what the movement in the link was). Typically they will have a single cap jewel over the balance wheel-more as a decoration than to serve any functional purpose. I'd venture to say that 1 jewel pin levers are more common than higher jeweled ones. Adding any jewels at all to them is sort of gilding the lily.

By the way, I often deal with watches that are described in factory records as "Plain", "4 holes", "4 pairs" and "4 1/2 pairs". Anyone want to take a guess at how many jewels each of those(respectively) represents? (and, yes, I do know)

6. Re: Number of jewels represented as a fraction?

Thanks for the info.

7. Re: Number of jewels represented as a fraction?

Originally Posted by Ben_hutcherson
Not at all uncommon pin lever movements(which is what the movement in the link was). Typically they will have a single cap jewel over the balance wheel-more as a decoration than to serve any functional purpose. I'd venture to say that 1 jewel pin levers are more common than higher jeweled ones. Adding any jewels at all to them is sort of gilding the lily.

By the way, I often deal with watches that are described in factory records as "Plain", "4 holes", "4 pairs" and "4 1/2 pairs". Anyone want to take a guess at how many jewels each of those(respectively) represents? (and, yes, I do know)
Here is my best guess.

Thinking pocket watches, please correct me where I am incorrect.

Plain: 7 jewels: balance, pallet forks, roller, escape?

4 holes: 11 jewels: adding 3rd and 2nd wheels?

4 pairs: 15 jewels: above plus capping balance, escape, 3rd and 2nd?

4 1/2 pairs: 16 jewels: above plus jeweling the mainspring?

Hopefully some of that is correct.

8. Re: Number of jewels represented as a fraction?

Here is my best guess.

Thinking pocket watches, please correct me where I am incorrect.

Plain: 7 jewels: balance, pallet forks, roller, escape?

4 holes: 11 jewels: adding 3rd and 2nd wheels?

4 pairs: 15 jewels: above plus capping balance, escape, 3rd and 2nd?

4 1/2 pairs: 16 jewels: above plus jeweling the mainspring?

Hopefully some of that is correct.
You do have the jewel counts correct...and I should add that the(obsolete) terminology could apply to any lever escapement watch although Swiss jeweling patterns aren't necessarily consistent with American practices.

"Plain" is indeed 7 jewels...two hole and two cap jewels on the balance wheel, the roller jewel, and the two impulse jewels on the pallet fork.

"4 holes" is 11 jewels. It includes all of the above, but adds hole jewels to the pallet pivots, escape wheel, 4th wheel, and 3rd wheel on the top plate side. There is some debate as to the effectiveness of this particular pattern. Some consider it deceptive, as adding jewels singly(rather than in pairs) to the pivots, some argue, doesn't really accomplish anything but gives the same visual appearance as a 15j watch. Others will say that pinion side of the wheel wears the most, and thus jeweling the pinion side provides a significant advantage even if both sides aren't jeweled(on most American 18 size watches, the pinion side is closest to the top plate).

"4 pairs" adds the companion pillar plate side jewels to the "4 holes" description above

"4 1/2 pairs" adds one jewel to the center wheel. Typically this is the top plate jewel-the one which most certainly does experience the most wear. Some very early American watches jeweled the pillar plate to the center.

By the same token "5 pairs" is 17 jewels. Looking at Waltham's hand-written records from the early days(where I'm taking this convention from) I can't discern any distinction for jewel counts higher than 17 despite the fact that Waltham produced plenty of watches so jeweled in the time the records I'm looking at cover. Typically, the higher jewel counts(i.e. 19j) had an additional pair of cap jewels on the escape wheel.

One also sometimes sees "2 pairs" as a jeweling pattern. This is also 11j, but is typically jewels on both ends of the pivots of the escape and 4th wheels, or sometimes the pallet fork and escape wheel.

9. Re: Number of jewels represented as a fraction?

Originally Posted by Ben_hutcherson
You do have the jewel counts correct...and I should add that the(obsolete) terminology could apply to any lever escapement watch although Swiss jeweling patterns aren't necessarily consistent with American practices.

"Plain" is indeed 7 jewels...two hole and two cap jewels on the balance wheel, the roller jewel, and the two impulse jewels on the pallet fork.

"4 holes" is 11 jewels. It includes all of the above, but adds hole jewels to the pallet pivots, escape wheel, 4th wheel, and 3rd wheel on the top plate side. There is some debate as to the effectiveness of this particular pattern. Some consider it deceptive, as adding jewels singly(rather than in pairs) to the pivots, some argue, doesn't really accomplish anything but gives the same visual appearance as a 15j watch. Others will say that pinion side of the wheel wears the most, and thus jeweling the pinion side provides a significant advantage even if both sides aren't jeweled(on most American 18 size watches, the pinion side is closest to the top plate).

"4 pairs" adds the companion pillar plate side jewels to the "4 holes" description above

"4 1/2 pairs" adds one jewel to the center wheel. Typically this is the top plate jewel-the one which most certainly does experience the most wear. Some very early American watches jeweled the pillar plate to the center.

By the same token "5 pairs" is 17 jewels. Looking at Waltham's hand-written records from the early days(where I'm taking this convention from) I can't discern any distinction for jewel counts higher than 17 despite the fact that Waltham produced plenty of watches so jeweled in the time the records I'm looking at cover. Typically, the higher jewel counts(i.e. 19j) had an additional pair of cap jewels on the escape wheel.

One also sometimes sees "2 pairs" as a jeweling pattern. This is also 11j, but is typically jewels on both ends of the pivots of the escape and 4th wheels, or sometimes the pallet fork and escape wheel.
At least the counts were right. I answered without the use of google, so the terms used were from memory if not made up, and probably not the most commonly used. Even the accepted industry names seems to vary.

It is interesting that they would cap the balance before jeweling the escape wheel. Is that a common practice I have just failed to notice, or limited mostly to American pocket watches?

That is the first I have heard of jeweling just the pinion side. Sounds more like marketing but may serve to reduce friction and wear somewhat. I was under the impression that pallet pivot jewels expirenced little wear and drag, thus they are rarely oiled. It surprises me that they would jewel such a low friction area instead of both sides of the 4th and 3rd wheels. What do you think of the pallet pivots? Does it make sense to jewel them before the escape, and do you oil them?

Very interesting, thanks for sharing.