Jump to content

Jacot tool and pivot file burnisher question


Recommended Posts

Hi

I got my hands on an old jacot tool and want to learn about cleaning pivots. Most all jacot tools on the net and u tube have a pulley  and string to drive it pretty self explanatory. 

The one I have on one side is the slots to rest a pivot on the opposite a bar that comes out with flat sides and a point not in the center but off center on the top of the bar.

Looking around e bay and pictures on the net I don't have the only one they seem to be much less common but they are out there.

My problem is I can't figure out the setup. Could someone show me how the balance would be mounted and spun, or point me in the right direction ?

I have looked around quite a bit before asking and just can't find any info on it.

Thank you, Tom

Link to comment
Share on other sites

Thessler,

The Jacot tool is essentially a dead center lathe. The off center looking part (center) on your lathe is actually aligned with the groove in the drum. One end of the staff (the pivot) goes in the center and the other end rests in the groove in the drum. The Jacot tool in your picture is missing the drive pulley assembly that is on some Jacot tools. The drive pulley assembly should rotate around the dead center and generally has two drive pins sticking out of the pulley. The drive pins will engage the balance wheel (if it is attached) and turn the staff. The pivot to be burnished rests in the appropriate groove so the burnishing file can be run over the pivot. If the part to be burnished does not have a wheel attached to it, then driving dogs (which are shaped like fish) are attached to the shaft. The pulley is generally powered with a bow that is strung with thin fishing line.

A high quality Jacot lathe, such as a Steiner, is generally in an encased set and should come ready to run. If you go to the OTTO FREI site you can pull up a picture of a complete Jacot Tool Set. The tool you currently have needs the additional components in order to work.

david

  • Like 1
Link to comment
Share on other sites

Yes, you are right... here is a similar one http://www.ebay.com/itm/Antique-watchmakers-jacot-pivot-lathe-with-brass-frame-steampunk-instrument-/322344296852

but I've looked through all my books and don't see one in use. Is it possible that you use the bow directly on the wheel staff? 


I made a YouTube video on using this tool.




Sent from my iPhone using Tapatalk Pro
  • Like 1
Link to comment
Share on other sites

Hello Tom:

Here's my setup. I bought a low RPM electric motor and a controller and just mounted the thing on a cheap wood carving board that I bought at Wallmart. Additionally, I bought the pulley and O-ring from eBay as-well-as the motor, the controller, and some rubber feet. The clamps is milled out of aluminum but they could just as easily be made out of wood - there's very little pressure on this operation.

If you want more specifics I 'll be glad to provide them.  Check out the video and let me know.
 

Thanks!

Tom
 

  • Like 1
Link to comment
Share on other sites

The pic Stuart references is the exact tool I have. It is not missing parts, the more common ones with the pulley have an extra shaft. Very similar tool but not the same.

The only thing I can figure is as Stuart suggested,  wrap the string around the balance shaft.

I'm guessing that's the  real good way to bend and snap off pivots. Maybe that's why the other style is more common.

Thanks for the thoughts, Tom

Link to comment
Share on other sites

Thessler,

There used to be special drive pulleys for that purpose but they are no longer made. The pulleys had a clamping bar on one side with a square notch. The shaft would be placed in the notch and tightened to the shaft with screws. There were a couple of problems with this method. The first problem was if the exact pulley was not used for a given staff, the pulley would be off center. The second major problem is the tool was bulky and pretty much unsuitable for smaller wrist watch staffs. I never heard of winding a string around the balance staff itself to drive it. It does not sound like something that would work.

david  

Link to comment
Share on other sites

20 minutes ago, david said:

Thessler,

There used to be special drive pulleys for that purpose but they are no longer made. The pulleys had a clamping bar on one side with a square notch. The shaft would be placed in the notch and tightened to the shaft with screws. There were a couple of problems with this method. The first problem was if the exact pulley was not used for a given staff, the pulley would be off center. The second major problem is the tool was bulky and pretty much unsuitable for smaller wrist watch staffs. I never heard of winding a string around the balance staff itself to drive it. It does not sound like something that would work.

david  

It's called a split ferrule and can be seen illustrated in De Carle's Practical Watch Repair at the beginning of the chapter on turning.

I have a few in various sizes including a couple that are small enough for some of the larger wrist watch balance staffs but have never used them for the reasons David has stated above. I guess that at a push they would be ok for roughing out the staff on a turns up to the point where the wheel could be riveted on allowing the use of a pulley wheel with a driving pin and then then turning the pivots, but if you were unlucky to subsequently break a pivot you would have to cut the rivet off again to remove the staff and start again. I can't see pivots surviving the lateral loading that the bow would exert on the ferrule.

Wrapping the bow around the actual staff would I'm sure be a recipe for disaster.

  • Like 1
Link to comment
Share on other sites

I think the best bet would be to make a small pulley to rotate on the dead center of the Jacot tool. It could be turned from a piece of brass rod with a small hole drilled in the center to ride around the outside of the dead center. The groove in the pulley can be cut with a V shape cutting tool. I think that would be the easiest way to get the tool up and running.

david

Link to comment
Share on other sites

Thessler,

Take a look at the Jacot tool sold by  OTTO FREI. I am pretty sure it is a Steiner. The cost of a new Jacot set is about equal to the down payment on a house so it would be a good idea to find a used one.  Once you can see what a complete set looks like, you can take a look at  used ones  for sale on Ebay. Also, check with Uncle Larry's Watch Shop.

david

  • Like 1
Link to comment
Share on other sites

Thessler,

Take a look at the Jacot tool sold by  OTTO FREI. I am pretty sure it is a Steiner. The cost of a new Jacot set is about equal to the down payment on a house so it would be a good idea to find a used one.  Once you can see what a complete set looks like, you can take a look at  used ones  for sale on Ebay. Also, check with Uncle Larry's Watch Shop.

david


I lucked in on mine, a real beauty


Sent from my iPhone using Tapatalk Pro
Link to comment
Share on other sites

  • 3 months later...
  • 8 months later...

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.




  • Recently Browsing

    • No registered users viewing this page.
  • Topics

  • Posts

    • this is something I've never quite understood about the some of the Swiss companies. In 1957 Omega was using 9010 for the keyless parts with epilam. there's been a slow migration towards using heavier lubrication's but still typically oils and epilam to keep them in place. When it seems like 9504 works so much better.  
    • OK, welcome in the world of alarm clocks... I guess the 4th wheel is dished because it is from another movement. If it was not dishet, then it would not mesh with the pinion of the escape wheel, am I right? The marks of wear on the 4th wheel pinion doesn't corespond to the 3th wheel table position, at list this is what i see on the picts. Calculating the rate is easy - there is a formula - BR = T2 x T3 x T4 x T5 x 2 /(P3 x P4 x P5) where T2 - T5 are the counts of the teeth of the wheels tables, and P3 - P5 are the counts of the pinion leaves. Vibrating the balance is easy - grasp for the hairspring where it should stay in the regulator with tweasers, let the balance hang on the hairspring while the downside staff tip rests on glass surface. Then make the balance oscillate and use timer to measure the time for let say 50 oscillations, or count the oscillations for let say 30 seconds. You must do the free oscillations test to check the balance staff tips and the cone cup bearings for wear. This kind of staffs wear and need resharpening to restore the normal function of the balance.
    • Glue a nut to the barrel lid, insert a bolt, pull, disolve the glue.  Maybe someone will have a better answer. 
    • The stress is the force (on the spring) x distance. The maximum stress is at the bottom, and decreases up the arm. That's why they always break at the bottom. I used a round file, then something like 2000 grit to finish. I gave the rest of the arm a quick polish - no need for a perfect finish. Just make sure there are no 'notches' left from cutting/filing. The notches act like the perforations in your toilet paper 🤣
    • It's probably a cardinal rule for watch repair to never get distracted while at the bench. Yesterday, after finishing a tricky mainspring winding/barrel insertion (I didn't have a winder and arbor that fit very well) I mentally shifted down a gear once that hurdle was passed. There were other things going on in the room as I put the barrel and cover into the barrel closer and pressed to get that satisfying snap. But when I took it out I realized I never placed the arbor.  When opening a barrel, we are relying on the arbor to transfer a concentrically-distributed force right where it is needed at the internal center of the lid. However, when that isn't present it's difficult to apply pressure or get leverage considering the recessed position of the lid, the small holes in the barrel and the presence of the mainspring coils. It was a beat-up practice movement so I didn't take a lot of time to think it over and I pushed it out using a short right-angle dental probe placed in from the bottom, but that did leave a bit of a scratch and crease in the thin lid. I had also thought about pulling it using a course-threaded screw with a minor thread diameter smaller than the lid hole and a major diameter larger, but that may have done some damage as well.  Thinking about how this might have been handled had it been a more valuable movement, is there a method using watchmaking or other tools that should extract the lid with the least damage? 
×
×
  • Create New...