I setup a type of turns on my lathe..NEED help for finishing the pivots on staffs

Discussion in 'Horological Tools' started by davestanda, Mar 21, 2013.

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  1. davestanda

    davestanda Registered User

    May 23, 2011
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    Hello i setup a type of turns setup on my lathe...It is kinda a reverse setup since the pulley goes in the tailstock and then with a taper collet i use another female in the headstock...I made some simple drivers ,the screw type, which i could do better, i was looking into the Bergeon set but i heard they aren't that good or worth the money...Anyway my problem now is in finishing the pivots ...I was wondering what could work, i don't have any of the runners or attachments that have the plate with the drilled holes in it for pushing the pivot through to finish...also i guess it would have to fit in the headstock in a collet...My lathe's bed does move just i could adjust the alignement ..I was thinking something like a small triangle shaped piece with groves cut in it attached to an arbor....I will take pictures when i get a chance...If someone has any ideas please let me know..thanks...
     
  2. gmorse

    gmorse Registered User
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    Jan 7, 2011
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    Hi Dave,

    Yes, your suggestion of a small triangular runner is a good one. If you make very small "pips" as near as you can to the points of the triangle, you can then stone down so that there's just enough metal to locate the conical end of the pivot, which should give you enough clearance for the graver to turn the parallel part of the pivot. You will need a lantern or rounding-up plate to finish the rounded ends however.

    Regards,

    Graham
     
  3. Max Phillips

    Max Phillips Registered User

    Sep 12, 2011
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    I also agree about the triangular notched bed. Depending on the angle you want to use for your notch, do a little bit of math to determine where the top of the bed should be in relation to the lathe center, and how deep to make the notch for the finished size of the pivot. Jere's site goes into the calculations required for this but I can't remember how specific they were to the angle he was using for the notches. I don't mind helping you out with the calculations if you need - feel free to PM me as always.
     
  4. davestanda

    davestanda Registered User

    May 23, 2011
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    Thanks max,,, I think my biggest problem would be finding a piece of scrap that would be easy enough to shape and cut......I know somewhere where i could get an old levin 6mm that has everything but the cross slide...I was thinking about getting that , but i really want a lathe with a cross slide..which is why i still thinking about the sherline, i have the money now just can't decide..
     
  5. Max Phillips

    Max Phillips Registered User

    Sep 12, 2011
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    Personally, I'd go with O1 tool steel - it's inexpensive to buy in annealed form, machines nicely, is easy to heat treat in the home shop (with a little practice), and warping is minimized during heat treating (because oil is a fairly slow quench). Air hardening tool steel (like A2) would probably be even better but from what I understand it's more difficult to harden (though if you had a little heat treating furnace it would probably be a cake walk).

    Also, buy the Sherline. :)
     
  6. Kevin Scott

    Kevin Scott Registered User

    Aug 2, 2011
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    Concerning the Bergeon set you mentioned, I assume you you are referring to #30090, driver dogs with opener.

    I like it and think it works very well, but at today's cost, it is up to the individual whether or not it is worth the money. DewyC posted about a system he uses that is cheap, easy to make, and works well. See if you can find his post.

    Triangular runners for pivot finishing: I have factory ones, and have used them, and like alot of watch tools, if you use them alot, make gravers etc that work in the tight space, etc etc, I can see how they can have value to some people. But they are not a miracle tool. And also get easily damgaed since they are made of thin hardened metal. Seems like the main advantage to them, and other between center tooling is you don't have to spend the time setting up a cement chuck when you can't get the work to run true in a collet.


    Still think the shovel system with tailstock guide and sapphire files and burnisher, is a great way to finish pivots and other diameters. As far speed, hard to beat. Sometimes you have to use a cement chuck, and that slows things down. Very easy to use and learn. Results wise, it is very hard to do better. Very low to nothing cost, but you do have to spend some time making the tools. Only someone very skilled with a Jacot tool can do be better with pivots. I am surprised more people don't use the system, especially since Fried and others highly recommend it. Some watchmakers tell me they don't need a guide system, since they do it enough to get good results without it. But if they did use it they would find their results much better. Unfortunately some people feel "good enough" is fine, even though with only slightly more time, great results can be achieved. But then they wonder why they have timing problems after the job is done. So they come up with excuses like the escapement or watch is worn out, or the watch is old, and it is as good as it can be.

    To put things in perspective, I use a 30x Leica stereo zoom microscope to evaluate pivot etc finish. At 30x a Hamilton Factory made staff pivot looks flawless. A good aftermarket staff pivot shows minor flaws at 20x. A lower quality one shows flaws at 10x.


    With the shovel system I can quickly finish pivots that are flawless at 25x or so. So far, have not been able to exceed that. Pictured is using a sapphire file made from a used Rolex watch crystal with the adjustable tailstock guide. I don't use a handle on the shovel like Fried and others use. Tried it, and don't see any advantage to having one versus the way shown. Sorry for the duplicate pictures. Can't figure out how to delete the extra one.
    P1000361 95%.jpg P1000361 95%.jpg
     
  7. davestanda

    davestanda Registered User

    May 23, 2011
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    Thanks for the reply i tried using a wax chuck but had no luck..i couldn't get the wax to hold..I was thinking about using super glue then using some solvent to remove the staff..Maybe i'm being to cautious with my collets all but my 50mm collet , spin very true..Daniels says in his book that regular collets work very well , the finish on a jacot tool...About reducing pivots with a stone ,i'm very good at getting the pivot very very close to the size i need without using a stone , i just burnish with my burnisher and then with a jasper stone...although i could use more practice rounding the ends...my problem is the second half of the staff, i wasn't that good at turning it all at once, so i have to flip the staff around...I am in the process of making some drivers like Clark's , i made one but since i used my only bad collet it was to off centered
     
  8. Kevin Scott

    Kevin Scott Registered User

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    Above, my responses are in bold.

    Also keep in mind that the further out the work is from the collet, errors magnify. So on a longer staff, more likely to not run true than with the same collet and work size on a shorter staff.
     
  9. davestanda

    davestanda Registered User

    May 23, 2011
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    well maybe not perfectly true, and i don't have a complete set, but the 50 collet is the only one that is bad bad, noticeable
     
  10. davestanda

    davestanda Registered User

    May 23, 2011
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    i understand that the burnisher is used to harden the pivot, i use it to get a polish on the pivot...
     
  11. davestanda

    davestanda Registered User

    May 23, 2011
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    Daniels does have alot on turning between centers. Daniels quote " Some errors of timing will result from this eccentricty which will need correcting by adjustment to the balance . As this is always necessary when the watch is to be submitted for observatory testing, this is not a reason for rejecting the staff or the method of making it..It is important only that there is no relatice eccentricity of the two pivots...For this reason the methods decribed for making the staff demands that the pivots are finished between centers or jacot lathe.... ..Which is what i said, that the pivots need to be finished on something else....
     
  12. davestanda

    davestanda Registered User

    May 23, 2011
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    anyway i was thinking about making some different runners to use kinda like a jacot lathe, just drill some different sized holes in some drill rod, then file half of the rod ,polish then use that too burnish and polish pivots...I would still need a way to turn the pivot though
     
  13. David Pierce

    David Pierce Registered User

    Jan 15, 2013
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    Max,
    There is a misconception that air hardening steel is "better" than oil hardening steel. The reason air hardening steel is used for certain applications is due to the dimensional stability after heat treatment. The worst stability is from the water hardening series which is subjected to the most shock in the hardening and cooling process. Oil hardening steel is quenched in oil which cools the heated part more slowly than water producing less shock and less dimensional distortion. Air hardening steel is quenched with AIR and the process produces the least amount of shock and the least amount of distortion. This is why it is used in critical precision parts like stamping punches and dies. When used to make stamping dies the steel would be wrapped in stainless steel foil and put it into a small kiln size furnace. When the part reached the proper temperature it would be taken out of the kiln, the foil removed and placed in front of a common fan.
    david
     
  14. Max Phillips

    Max Phillips Registered User

    Sep 12, 2011
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    Yes, that's pretty much what I said. When I said air hardening steel would be best I think it's pretty clear we were in the context of this specific application. If we're talking about making pivot polishing runners then I think the least amount of distortion during heat treating would be best.
     
  15. davestanda

    davestanda Registered User

    May 23, 2011
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    #15 davestanda, Apr 2, 2013
    Last edited: Apr 2, 2013
    making good drivers for tURNning between centers that work ,besides the screw dog type something like the bergeon ones but quick to make the others are just to much of pain to use for small parts, like staffs...
     
  16. davestanda

    davestanda Registered User

    May 23, 2011
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    Here are some pics of my lathe with my "turns" setup ...also some lathe dogs i made,they aren't pretty ,they work, but like i said are too large for staff work..also is a female center i made for staff pivots,,which does work..Also the pulley in the tailstock, the centers in that remove so you can use other kinds as well..I paid two dollars for it off of ebay and then had the tailstock runner drilled to accept the shaft of the pulley...Which i use my motor for ,since , I think it is too large to use with a bow...I 95percent sure that pulley came from some old boley or lorch lathe that was made to be setup as turns....Which was the whole point of me using this setup...Anyway i though i would share some pics..Also it is weird working from opposite way, but my lathe bed moves and swivels so i can move the tailstock to where the headstock would be, just i would have to move my base and motor.... IMG_6784.jpg IMG_6785.jpg IMG_6786.jpg IMG_6787.jpg IMG_6788.jpg IMG_6789.jpg IMG_6790.jpg IMG_6791.jpg
     

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