Help understanding small seconds pivots and sizes

[DFeryance]

I have collected a small assortment of movements to practice servicing them. Most are quite old so they don't have center seconds. I've been quite confused over if the movements support a small seconds hand or not.

I have a Peseux 7016. This movement doesn't seem to have an extended pivot on the forth wheel. I see the jewel exposed to the top plate but the pivot doesn't come up to the top of the movement. When looking at the parts list at jules borel, I see there is a forth wheel regular, and a forth wheel w/ second. So from that, I presume the variant I have doesn't support small seconds. Does that sound right? I was able to get a small seconds hand to turn a bit by placing it in the forth wheel hole but it wouldn't stay on the pivot.

Another movement I have and looked at is the Peseux 7001. I noticed from different sellers that there are variants with and without small seconds as well. However this movement does have a pivot extending above the top of the movement. So this is quite clear it supports a small seconds hand. It wouldn't be possible to fit a dial on it without a hole for the small seconds.

Based off of the above two movements, my conclusion was: if the pivot extends above the movement, it supports small seconds and if it doesn't, then no small seconds. However.... the next movement contradicts that.

I also have a Gruen Precision movement. Unlike the other ones, this came with a dial and hands. I know for sure this supports small seconds as it came with a working small seconds hand. However, the forth wheel pivot does not extend up to the top of the movement. It looks very much like the 7016. However, in this case the small seconds hand tube is long enough to reach into the movement and grab the pivot.

So now I am at a loss. Could it be that my Peseux 7016 does actually support small seconds but I just need a hand with a longer tube? Is there some general way to inspect the movement or forth wheel to determine if the pivot is long enough to support a small seconds hand? I plan to tear it down to service it but haven't done that yet.

[jdm]

7 minutes ago, DFeryance said:

 

So now I am at a loss. Could it be that my Peseux 7016 does actually support small seconds but I just need a hand with a longer tube? Is there some general way to inspect the movement or forth wheel to determine if the pivot is long enough to support a small seconds hand?

Yes there is, under the microscope you can tell if the pivot has snapped. Check AliX for cheap USB microscopes or Ebay for used ones.

Also possible the mov't was made for a time only watch and fitted with a short pinion.

Edited July 31, 2019 by jdm

[DFeryance]

Well I've been wanting a microscope for a while. I have 10x lenses but that doesn't compare to what a microscope can do.

In general I guess I'm just confused at the movement inconsistency. It seems really hard to figure out if a movement is hour+minute only or if it supports small seconds since there are often different variants with the same caliber number.

[nickelsilver]

If the pivot can carry a hand it will extend well past the jewel. Normally pivots don't extend any higher than the jewel. It's possible for a jewel to be countersunk well below the plate surface, in which case an extended pivot wouldn't necessarily extend past the plate surface.

Can you manage a pic of your Gruen?

[DFeryance]

I can see why jdm recommended a microscope. I took pictures with my best digital camera and a flashlight and still have trouble getting good detail. 

This is the gruen movement. 

And then the peseux 7016

 

On camera, in both cases you can see the pivot. For sure the Gruen support a seconds hand as I have the dial and hands. But I am unsure on the 7016. It could be that the pivot is extended as it is visible, but it could also be flush with the jewel and visible as well.

Here is the Gruen with the dial. It is clearly old but seems quite serviceable. I don't have the case but I plan to make one to turn it into a full watch.

 

[jdm]

7 hours ago, DFeryance said:

I took pictures with my best digital camera and a flashlight and still have trouble getting good detail. 

Place the loupe over the lens. But in the end if you want the "trotteuse" you need a wheel with a pivot long enough.