Jump to content

Pivot Sizes


Scouseget

Recommended Posts

I've been having lots of fun, and a good deal of frustration, working with a couple of English fusee pocket watches from around 1875. Surprisingly, I've been able to semi-master the intricacies of the fusee cone (dismantled, cleaned, lubricated, and reassembled) and chain (which was broken but I was able to repair it with the tiniest of rivets
), but am being presently stymied by a broken English lever arbor pivot on one of them. One end is not only broken but also missing so I can't establish the diameter, so my question is, are the pivots usually the same diameter on both ends of any arbor? This can be for a balance, lever, or indeed any other wheel arbor? Can we make that assumption, and if not, how do you make a replacement arbor, which is next on my work list for this watch, if you don't know what diameter to make it? 

I do realize that I can simply try the remaining arbor in both jewel holes and try to establish the size that way, but it's a bit inexact and frankly I don't know how much clearance is normal, i.e., if a jewel hole is, say, 0.15mm, what size should the corresponding pivot size actually be?

I see that occasionally jewel gauges come on sale on E Bay, but these appear to be rare beasts at the best of times, and are usually prohibitively expensive so is there another method of measuring a jewel hole size? 

Finally, why wouldn't the pivots be the same size on an arbor? Presumably the loading on each of the pivots would be the same so logic dictates that the sizes could also be the same, or am I missing something and making too many assumptions?

As always, thanks in advance for any light you can shed on this.

The first photo shows the broken arbor. The second is the fusee opened up. Amazing precision given the technology of the day I think.

P7224323.JPG

P6244260.JPG

Link to comment
Share on other sites

For starters, you need the right tools to begin with. A good lathe and milling. The arbor is made out of a single piece of steel. You need to measure both holes in the plates and barrel, then you need to be able to draw up plans and design the arbor, taking a look at others will help.   

Link to comment
Share on other sites

On 9/6/2017 at 3:31 AM, Scouseget said:

I see that occasionally jewel gauges come on sale on E Bay, but these appear to be rare beasts at the best of times, and are usually prohibitively expensive so is there another method of measuring a jewel hole size? 

Do you have a lathe?
You can then turn a series of trial pivots of a known size, pressed into a small brass handle.

Link to comment
Share on other sites

1 hour ago, oldhippy said:

I wouldn’t think this type is expensive.  

 

index.jpg

Depends on your idea of expensive.

Second hand anything from £50 to £120.

Its on my want list, but so are many other items

Link to comment
Share on other sites

I think he was referring to my post which was about the pivot gauge for pivots, not your post about the hole.

On clocks you can measure the pivot hole with a smoothing broach and then a vernier or micrometer on the broach, I've never tried to measure the pivot hole on a watch, but can you do the same if you have fine enough smoothing broaches?

Link to comment
Share on other sites



  • Recently Browsing

    • No registered users viewing this page.
  • Topics

  • Posts

    • people be honest.... Swatch is evil for the watchmakers and repairers, BUT not everything in watches from Switzerland is from the Swatch-Group. As far as i know, Selitta got sacked by Swatch as a Movement-Assembler for them and they started to produce Movements in their own Name with slight Modifications. As far as i know, they sell Parts to the Market for their Movements. In most cases, if a ETA-Movement fails, it is a valid Option to replace it with a Selitta Movement, which i consider the Solution for this Mess with the Swatch-Group...... I have no Connection to anybody at Selitta, but being a Swiss-Guy, i still like to have Swiss-Made Watches, but not from the Swatch-Group.   ok ? regards, Ernst
    • Just one more greedy act by Swatch. They started a number of years ago here in the US..cutting off supplies to watchmakers that could build complications that many Swatch houses couldn't even touch. Old school masters who had gone through some of the most prestigious houses in the world. Otto Frei has some statements on their page about it. I tell all my customers to avoid new Swiss watches like the plague,..unless they just want an older one in their collection that still has some parts out on the market, or they have really deep pockets and don't mind waiting months and paying through the nose to get it back. Plenty of others to choose from..IE Seiko,..or other non-swiss brands Even a number of Chinese brands are catching up with the Swiss,..and I think that in time, their actions will be their downfall
    • Yes. If that's not what you are experiencing...start looking for something rubbing. A 1st guess is that one of the hands is rubbing against the hole in the center of the dial. Especially if you now have lower amplitude in face up/ face down positions.
    • Once a movement has the dial and hands put back and it is recased, would you expect the assembled watch to have the same amplitude as when the movement is in a movement holder and is without hands and dial? Thanks
    • C07641+ not sure what the "+" is for after the last digit.
×
×
  • Create New...