Reply To: Roller jewel and fork

[Bob Tascione]

Hi Chaplin37,

You can determine whether the the staff pivot/jewel hole fit is correct by checking how much the staff tilts in the jewel hole. If you take a look in the online course at Video 3 and then click on the “Test Staff” in the quick navigation menu it should help out.

You can remove material from a pivot end using a pin-vise and very fine stone. It’s very difficult to obtain a flat pivot end using this method. It can be done by doing the job on a soft cork sheet but it takes some practice and still no guarantee that the pivot won’t end up with a slight point or an off angled flat. Neither of these conditions is good. Some people feel that a flat bottom will perform better on watches with fixed stationary cap jewels (non shock absorbing jewel settings like KIF and Incabloc) than a conical end while others prefer conical for fixed cap jewels. If you’re going to use the pin-vise method you should shoot for a conical shape which I feel is fine for your fixed cap jewel pocket watch.

Here’s the method that I used to use. You can modify it to suit your needs..it’s just what worked for me. I like to let the weight of the pin-vise (small pin-vise) do the grinding. With the staff chucked in the pin-vise I rest the pivot on a very fine stone which is laying down on a flat table top. Then tilting the pin-vise toward me about 10 degrees or so and holding the end (top) of the pin-vise between my thumb and index finger I would spin the pin-vise while pulling the bottom of the pin-vise towards me with the index finger of my other hand. When doing this I would keep the position of the top of the pin vise stationary. I would pull the bottom of the pin-vise up to and then just beyond vertical position and stop when the top of the pin-vise was tilted a few degrees in the other direction. It’s important to pass the point where the pin-vise is straight up and down and VERY important stop pulling while the pin-vise is still spinning and not before. By allowing the weight of the pin-vise to apply downward pressure rather than pushing down with your hand you’ll only grind a tiny bit off with each pass. This is important when using this method since the staff is making very few rotations while pulling and small flat areas are likely to form. By making many lighter passes you should end up with a smoother more even surface. The remaining unevenness can then be polished out.

I’ve made the process sound much more complicated than it actually is. Once you set it up and do it it’s simple.

The end of the pivot must now be polished. I’ll explain briefly three methods here. You can use Diamantine powder (most watch supply houses) and a flat piece of iron or copper. Sanding smooth a copper penny works well. Diamantine is extremely hard and will tend to embed itself in anything that’s softer than it. The steel pivots are softer so if the polishing is done on a surface that’s as hard or harder than the pivots the diamantine will become imbedded in the pivot. If this happens the charged pivot can actually grind a hole in the cap jewel over time. By using a softer plate like copper or iron the diamantine will become embedded in the plate rather than the pivot and will polish the pivot to a mirror finish. The polishing process is done the same as the grinding process only with a soft plate and diamantine powder rather than a stone. If only a very small amount needs to be removed from the pivot then using diamantine rather than a stone can do the job. When using diamantine remember to clean the pivot very well before inserting it back into the jewel hole for testing.

Another very good way to polish pivots and at the same time eliminate the risk of diamantine becoming embedded in the pivot is to use a Jasper stone. I personally find that diamantine gives a smoother “blacker finish” but many people use a jasper stone and like the fact that they don’t need to worry about embedded diamantine.

If you’re in a hurry and don’t have any diamantine or a jasper stone you can still get a good finish by making a quick burnishing tool, preferably out of something harder than the pivot. The only problem with burnishing when using the pin-vise method that we’re discussing here is that burnishing doesn’t really remove much if any material but rather lays the steel over itself. You can get a beautiful extremely smooth polish using burnishers but the unevenness that I mentioned earlier may still remain. If you decide to burnish then an old flat jewelers file works great. Just grind one face smooth with a stone. You can then take a coarse stone and lightly cross grain the face of the file (not down the length but across at 90 degrees until you see some very fine lines). This will be enough to lay over the steel of the pivot and will impart a nice polish to the pivot end. You can then apply a small amount of oil to the burnisher when polishing. The actual method of polishing with the burnisher is the same as above.

I hope this helps Chaplin,
Bob