How much pressure to use

Discussion in 'Watch Repair' started by Rob P., Apr 14, 2017.

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  1. Rob P.

    Rob P. Registered User

    Dec 19, 2011
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    I've been a slacker and haven't done the pivots on the 1880 key wind yet. Nearly a year in limbo. So, to refresh memories, I have to reduce the pivots on a new staff from P16's to P15's and fit them to the jewels.

    I have a burnisher and pivoter with proper posts in good condition.

    I just don't know how hard to push in order to move the metal and reduce the pivot diameter. I know it's hard to tell me but anything helps. Is it moderately light and lots of bow driving? Or is there a heavy bearing down and only a few turns with the bow?

    I'm thinking Sunday I will try to do this.
     
  2. Mark UK

    Mark UK Registered User

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    Great question Rob, like you I have two movements in 'limbo' which have new staffs and are running great but could do better with a little pivot burnishing... I have the tools, I have the time, I just don't have the experience which daunts me a little :)
     
  3. Rob P.

    Rob P. Registered User

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    I didn't get to this yesterday. :( Just not enough sleep to be steady or able to concentrate. Which lead to no motivation.

    I have a lot of things to do before this one is ready for this step anyway. I have to restaff the balance wheel so I can drive the new staff off the arm (because I don't have the little clip-drive dog things). I have to pull the lower jewel from another movement to replace a bad lower in the 1880 too.

    Once the staff pivots are reduced, I will have to modify the lower jewel chaton to shorten the between-the-jewels distance. This is because the correct replacement staff is not available and I have to use a "new style" staff which is .001" shorter overall. (though I might get lucky and the burnishing might move enough metal to lengthen the pivots enough. I doubt it, but I can hope.)

    I need to check again to see if the front plate escape wheel bushing absolutely has to be repaired/rebushed. I don't like the looks of it, it looks pretty beat up. There's a raised ring of metal around the pivot hole in the plate. But that could be gilding flash.

    At least I made a written list of the things this one needs. That way, if it takes another year to get back to it, I'll at least know where I left off. So, I actually did accomplish something. I definitely feel the itch to get this one off the bench, so I'm looking to find a few hours here and there this coming week. We'll have to see.
     
  4. gmorse

    gmorse Registered User
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    Hi Rob,

    You're right to doubt it, you won't stretch it by that much.

    The burnisher needs to travel about 15mm in each direction for about 50mm of bow stroke, so the pivot is always turning before any pressure is applied by the burnisher, otherwise you risk forming a flat. The right pressure is difficult to describe but it needs to be firm and held so that it produces a cylindrical surface. Checking the fit after every few strokes will soon show you whether you're having any effect. The amount of metal being moved does depend on the hardness of the staff and the way the burnisher is dressed, as well as the pressure you apply. Be careful when burnishing staff pivots that you don't apply any pressure to the cone, or you risk a breakage. Some Jacot tools have a guard to keep the burnisher away from the cone. Mine didn't have one so this is home-made.

    Regards,

    Graham
     

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  5. RJSoftware

    RJSoftware Registered User

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    Thing that makes me procrastinate is finding a suitable staff to turn down to from my pile of unsorted staffs. It's more work to find one that I can make work by adjusting in the lathe than maybe to turn the thing by scratch from stalk. Depends on how lucky I get. I measure length first by guessing (usually have to add for missing/broken pivot and adjust caliper) and then do a "go or no go" through the caliper on the possible staffs. I eyeball the thickness to pick the best of the candidates and then measure and hope they are equal or bigger.

    You ever notice though that it's the first move thing that causes the most delay. I find that if I just open the case or remove the movement then I am prone to continue. But otherwise I just sit and dream about something else. The internet is a time sucking vampire.

    RJ
     
  6. gmorse

    gmorse Registered User
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    Hi RJ,

    You're so right . . . .

    Regards,

    Graham
     
  7. Rob P.

    Rob P. Registered User

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    I spent a couple of hours this morning on this one replacing the cracked jewel with a pair from another KW I have that's a parts only movement of the same grade. Someone wrecked the heck of of that one, stripped screw holes and everything - it's toast.

    As for the 1880, I got the balance restaffed too. So, all that's left is to fit the pivots to the jewels. I think maybe Saturday I'll try to get back to it for this task. Then we mock it up and see if the overall length works or not.

    I think the scale I'm going to use to describe the pressure needed is going to be from 0 to 10. With 10 being unreasonable and guaranteed breakage and 0 being just resting the burnisher on the pivot with just it's own weight. 5 should be something like light draw-filing on steel. I'm thinking a 3 should be the right amount of pressure. I'll find out.
     
  8. Mark UK

    Mark UK Registered User

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    3/10 sounds about right :)

    I like the idea of the guard that Graham suggested as I can't afford too many breakages, staffs aren't that expensive but the cost of postage trebles or quadruples the price.
     
  9. karlmansson

    karlmansson Registered User

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    One good thing to keep in mind that I learned from a helpful someone here is to remember to always rest the burnisher flat on the edge of the BED. Not the pivot. If you rest it on the whole flat of the bed right away you will only contact the tip of the pivot and it will become conical as the tip dips away from the burnisher when the whole pivot is reduced. You need to keep the burnisher in good contact with the edge of the bed at all times. That way you are taking off an equal amount along the lenght of the pivot the whole time. When you are finished the burnisher should be resting perfectly flat on the bed.
     
  10. gmorse

    gmorse Registered User
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    Hi Rob,

    You have the right approach; start light and get the feel for the action, checking all the time, and don't forget to keep everything well lubricated. A light spindle oil like 3-in-1 will do.

    That steel guard piece is illustrated and described in "Watchmaking" by George Daniels.

    Regards,

    Graham
     
  11. Mark UK

    Mark UK Registered User

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    Karl, do you mean rest the burnisher flat on the back edge of bed or front edge of bed? I imagine the answer depends on if you only burnish on the down or up stroke of the bow..... and whether the staff is rotating clockwise or anti-clockwise.... and whether the bed is on left of jacot or on the right.... or am I making it seem harder than it really is :)
     
  12. RJSoftware

    RJSoftware Registered User

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    #12 RJSoftware, Apr 19, 2017
    Last edited: Apr 19, 2017
    What he said was to just rest the tip of the pivot (the cylindrical part) on the selected Jacot bed. And to set the burnisher/file with rounded corner towards the cone portion of the pivot but first work the cylindrical portion.

    This is what I find. Holding a long burnisher/pivot file by the end and trying to feel if it is laying flat on the oh so small Jacot flats is difficult. What I did cut a small portion of my pivot file so I could use one finger to hold it.

    When I hold a long file by hand and the file does not fit squarely on the flats I find I wind up present the pivot with an escape route and it will roll out. Also is the dreaded snap from when the pivot rolls out of the bed and then binds in crack between flat and file held at not so perfectly square to the Jacot flat.

    So I cut a portion of my pivot file about 1/2 inch long. Then when I set the tip of the pivot in the bed of my choice I carefully lay the file as described and hold my finger on top which has better ability to keep the small portion of file flat to the Jacot flats.

    This increase in control actually allows me to start off with larger stock in the Jacot bed. So I can start reducing a couple/few sizes larger than the goal bed. I really don't have to do anything but hold the portion of file squarely to the bed as it seems to cut just fine. But I move it a small amount anyway for improvement. Some say to load a file with chalk to prevent clogging. Also an ultra sonic is suppose to help in unloading clogged file. But I think that is for larger work. I have not tried it.

    The whole purpose of using the Jacot tool is the controlled reduction. The pivots laying in the bed can only be reduced to the depth of each bed, but they do not start out that way. So they are problematic as the extra height above the bed affects how well one can hold the file to the flats.

    The ultimate solution is like the Roll-o-fit. Where the Jacot tool is held in a device and a controlled arm with a carbide wheel descends in perfect position on top of the pivot to reduce the cylindrical part by micrometer adjustment. All while turning a hand crank and applying simple finger pressure with little skill required.

    I created my own Roll-o-fit type tool and it's base is a vise that I can power my turns, pivoting tool and Jacot. It does not have the controlled arm with the carbide wheel but after cutting the portion of pivoting file I realize that I don't need it.

    I recently installed a window crank for a handle. Basically it's just one upright board with hole for 1/4" all-thread axle that turns a large wood drive pulley with a groove for a rubber-band that drives the Jacot pulley/dog. The upright board is attached to a wood base which has a mini vise screwed down to hold the Jacot. (I hate that my camera sucks).

    Anyway, it makes life easier. To further improve the Jacot situation I put a coil of pocket watch mainspring and cut a notch on end so that I could reach up with the spring and attach it to the balance staff. What I wanted was a way to keep the balance staff (I always have balance wheel attached to drive it) and balance wheel in place. So the spring notch is set on the staff so to keep it from jumping out of the bed -ever.

    It worked so-so. The ability to adjust the downward tension of the spring needed improvement. I could crank the wheel at full speed and it would stay in the bed. But the extra effort to hang the spring on top and not have it pull to hard was issue. The other side of the spring was super-glued on to the Jacot tool and it broke off and I never felt compelled to have it on again.

    I improved my design as of lately to finally get my pivoting drill to work. I made mine out of aluminum with 1/8th inch brass inserts.

    The 1/8th inch size is all about the Dremel. Yes...!!! Love it. Now I have finally made my pivoting drill to use the carbide bits and it works like a dream.

    Well, it' didn't at first. I was going nuts. I got my pivoting tool all done took my time. Then came the Chinese PCB carbide bits. I ordered a bunch of them cause they are cheap. Start off at .1mm so it's small enough to do the staffs and others stuff. (cant' wait to have to do an anchor pivot).

    Anyway, so I get the bits. I get to work on a staff. All needed to do was remove the hairspring and then grind a small flat of the broken pivot which was on the hairspring side.

    So I get to drilling. I look, got a nice dimple. Drill some more. Still only a small dimple. What the heck...?

    I busted a bunch of the smallest bits I had. Kept freaking trying and trying. What the heck is going on.

    Then I realized... the balance wheel was slipping on the staff. So the wheel was spinning away but the tiny staff wasn't turning.. Rats....!

    So I staked the staff on tighter and then whaaaa lahhhh success...!

    I had 5 sets of those drill bits and ate every small one I had.

    Oh and another thing. I had some bust on me as they tend to roll off of a flat surface. So I screwed a magnet to the upright to grab the bit.

    The small drill bits are soo delicate. Like an uncooked blond angel hair pasta from Save-A-Lot.

    RJ
     
  13. karlmansson

    karlmansson Registered User

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    No RJ, what I said what was Mark was asking about. I usually use the back edge of the bed. But as you say each their own!
     
  14. gmorse

    gmorse Registered User
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    Hi RJ,

    I believe Rob and Mark are talking about burnishers not files, and the Jacot is really best used for burnishing pivots which are almost to size to start with. I'm not clear how you can give the file/burnisher enough travel if it's only 1/2" long. One thing about placement of the burnisher is that you can hear a different sound from when it's acting correctly on the pivot and when it's just on the edge of the bed.

    Regards,

    Graham
     
  15. karlmansson

    karlmansson Registered User

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    I normally use around 1/2" of travel when burnishing small pivots. Maybe that's what RJ meant?
     
  16. Mark UK

    Mark UK Registered User

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    I think Rob was intending to reduce a pivot size whereas I would like to burnish a few pivots following successful re-staff using 'unfinished' staffs I got from fleabay - so I am probably confusing things.

    I have a couple of oversize staffs but no lathe, but I do have a couple of spare beds that I am tempted to keep to one side just for filing, and keep the good beds for burnishing.

    RJ, those cheap PCB drill sets are pretty handy. I got my monies worth out of a .2mm bit the other day before it snapped on me, so I ordered a few more sets.
     
  17. RJSoftware

    RJSoftware Registered User

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    Ok, no problem. I'll explain.

    I do filing on the Jacot and burnishing.

    And yes I physically cut a chunk of my pivot file off the end that also included the one section with the tiny round edge.

    I got the pivot file/burnisher with a bunch of other tools. So I figure why not.

    But, it works.

    If you can't understand how it can still file, ask yourself how many teeth that chunk of file has. Probably in the range of 50 or so... In case of newbians don't understand, a pivot file has teeth finer than frogs hair. It's much finer than even the small jeweler files. The teeth are soo small you have to use magnification to see them. But then now you know why they are expensive.

    Why did I do it? Well, because I have difficulty with my finger sensations. It took me a long time before I could feel ant bites or even hot water on my left leg. My arms and legs have difficulty with sensation and numbness.

    This is not a pity thing. I am doing well. I am use to it and I don't even think about it hardly.

    But, the issue is there.

    So I resolved it. Now I can place my finger firmly on the small piece of pivot file and then turn the crank which powers the Jacot which files the pivot down.

    Now you guys say... well your' suppose to have pivots mostly done and only need to slightly modify I guess.

    Ok, but seems sometimes I miss the mark. But I get there...

    So say the objective is to produce a common staff with pivots at 9. I crank out a staff on the lathe and wind up with pivots at 11. I just do the rest on the Jacot tool with the pivot file. Why not?

    Lay the 11 size pivot in the 10 bed, put the piece on top and turn the crank. I do a little wiggle so to improve the cutting but not much. Before you know it, it's done. Then I move to the 9 bed and same thing.

    The last step I do burnishing.

    Thing is I might not be in the same quality of results as you guys. But what I do works.

    RJ
     
  18. karlmansson

    karlmansson Registered User

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    I see what you mean now RJ.
    Does give you good results? What you are describing is basically turning as your file isn't moving but the work is. The pivot files I have are all cross cut. That means that they need to be kept moving or the grain of the file will imprint on the work. A burnisher on the other hand, that is "single cut" perfectly perpendicular to the work, will leave no such imprint. It also needs to be kept moving though to prevent any buildup of metal particulate from scoring the pivot. That and any lateral movement will average out the inconsistencies in the burnisher.

    I see how this is the optimal solution for you, considering your condition. But I think the visual and sensory aid of a longer burnisher is preferable for someone with well functioning sensory systems. It's easier to tell if your tool is slanting if it's longer. And it's also easier to tell if you're rocking the burnisher of its long.
     
  19. Rob P.

    Rob P. Registered User

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    Well I figured it out. A 3 or maybe a 4 is about right. You don't need a lot of pressure to either reduce or burnish. Mostly it's the speed of the bow that does the work. I also wiped the tool with oil rather than dropping oil onto the pivot. Much less messy and the pivot got oiled during the work.

    Unfortunately, I snapped the pivot during the final burnishing after I fit the thing to the jewels. I knew I probably would, but I'd hoped not to. My luck is like that - do everything perfectly up to the very last second then BAM!, it's ruined and now I get to start over. Oh well, off to find a new staff.

    I did notice I had a pretty good step at the bottom of the cone. Is this normal after reducing pivot size? Or do I not have enough of a rounded edge on the file? Hmmm, maybe I need a new file too...
     
  20. karlmansson

    karlmansson Registered User

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    The step is sometimes there but the goal is to have no step. You should burnish the cone as well, just take care not to put the pressure concentrated on it. That will snap the pivot. I think pivots reduced by the Pivofix machines often have a rounded step after burnishing. at the very least the step should have a radius.
     
  21. Rob P.

    Rob P. Registered User

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    I looked at my tooling; the rounded edge which should go next to the cone is pretty sharp. So I'm going to do some shaping on it. I can still use this staff for more practice.

    What was interesting to me was that the pivot snapped halfway rather than at the bottom next to the cone. I still can't see how I managed it, the pivot was fully filed and the tip was not even near the edge of the cradle when the tool slipped into the gap between the cradle and the bed. I shouldn't have been able to damage it at all, but when it slipped I heard that tiny snap and knew it was gone even before I visually checked it.
     
  22. gmorse

    gmorse Registered User
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    Hi Rob,

    I'm not sure what you mean by the cradle, is it the land behind the bed without the recess for the pivot? When you're reducing a pivot to fit in a given jewel, it's better not to file until it fits fully, but until it just about fits, then burnish the rest of the way to a proper fit. In theory, it doesn't matter if there's a step if all the part of the pivot that fits in the jewel is cylindrical, but it does look better aesthetically.

    Regards,

    Graham
     
  23. karlmansson

    karlmansson Registered User

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    Rob, I've had the same thing happen. The cause is trying to burnish too much. You should get it down to where you are a couple of thousands away from final dimension, either on the late or by using a pivot file. The staff breaks like that due to stresses in the material. It's like bending steel wire back and forth. The staff work hardens and the more you keep compressing it the harder it gets. Finally it gets dead hard all the way through or
    the stresses from the pressure you apply gets too much. While
    burnishing takes off a minuscule amount of material the majority of the reduction comes from compression.
     
  24. karlmansson

    karlmansson Registered User

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    Graham, I've wondered about the "trumpet" shape of balance staffs. My understanding is that it's there as a compromise between a thin pivot and a strong pivot. It grows thicker as the leverage from the jewel increases. In other words, there should be no weak spot where the staff can break if subjected to shock. But wouldn't a staff with a step in it from burnishing have such a weak spot?
     
  25. Rob P.

    Rob P. Registered User

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    Terminology, I suck at it.

    What I call the cradle is the part with the semi-circular recess for the pivot. It cradles the pivot while you work on it.

    The bed is the wide flat hexagonal area. There's a gap between the cradle and the bed - maybe 1/16" wide.



    I believe the cone is just a stress relief radius. Sharp corners in metals that are stressed tend to break at the base of the shoulder. A radius reduces that chance.

    While I'm looking for a new staff, I'm going to get some wire and make a set of pivot gauges. I'll get more practice and hopefully won't break the next staff. And I get new tools too!
     
  26. gmorse

    gmorse Registered User
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    Hi Rob,

    I think you have that the wrong way round; the bed is the part with the pivot recess, and the part behind it is just the backing flange to support the burnisher. We all suffer from jargon!

    I should have added that the sweep of the cone from the cylindrical part of the pivot does make for a more robust job, as you rightly point out.

    If you haven't already got it, one of the most useful tools I can think of is a copy of "Watchmaking" by George Daniels.

    Regards,

    Graham
     
  27. RJSoftware

    RJSoftware Registered User

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    #27 RJSoftware, Apr 24, 2017
    Last edited: Apr 24, 2017
    I know this is true because I have done it a few times. Also this is why I go ahead and file with the pivot resting in a larger bed then when that is done proceed to next smaller till I get to target size.

    It's the control of the reduction provided by the Jacot bed that has it's appeal for using early vs struggling with measure on the lathe which sometimes promotes a snap.

    I have the microscope lens with the grid lines and pin gauges to do comparing. But these are rough estimators. Sometimes using them alone I fail at critical measure such as the hairspring collet portion. That one is more critical to me than even the roller side. This is because I can taper/feel my way for the balance wheel seat and taper/feel the roller. The hairspring/collet is too awkward to test so I wind up sticking the best fitting pin gauge in the collet and go from there. Many times I cut a tad bit too far and then I try to compress the collet to restore the grip. I can compress it with cone punch. But not always.

    Thing is, it's hard not to just try to slap the whole thing out with the lathe and then the Jacot. I have turn by centers and I have shellac chuck both are good solutions but I also just want to get the job done and find that I don't want to bother to set up either.

    I have to force myself to be more systematic. Of the two (turn by centers or shellac). Turn by centers is easy to remove and measure. Shellac you have to unglue.

    I see some people grab the jewel with some Rodico or similar and test fit the pivot. That would work on the lathe but for me, I don't know. I hate to drop stuff.

    If I can master the jewel on the stick trick, then I can skip the tbc and shellac.

    RJ

     
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