How do you polish THAT end?

Discussion in 'Clock Repair' started by fbicknel, Aug 25, 2019.

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  1. fbicknel

    fbicknel Registered User

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    2019-08-25 1542 Screenshot.png

    I thought I was going to get away with clamping the short end in the collet, but the pin hits the clamping nut and I can't do that.

    The jacobson chuck won't grab the shaft on that end, as it's too short. And I don't think I have any business clamping the pivot for fear of breaking or bending that pivot.

    So how does one polish the pivot on the other end (red arrow)?
     
  2. R. Croswell

    R. Croswell Registered User

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    There are several options. Put a brass bushing in the lathe collet that fits the pivot at the wheel end. Rest the pivot at that arrow in a "runner" in the tail stock. (The runner is a wood or brass rod with a hole that fits the pivot with half of the rod filed away in the area of the pivot to form a cradle in which the pivot rests with the top side exposed for polishing). Use masking tape to tape the wheel to the collect holder. The tape will drive the wheel with no loading on the pivot except holding the arbor on center. You will need to apply finger pressure to ensure that the pivot does not jump out of the cradle. In place of the runner you can use the lathe's steady rest if you have one to support the arbor near the "arrow". Use your regular polishing media.

    RC
     
  3. Bruce Alexander

    Bruce Alexander Registered User
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    If you have a steady rest, you can carefully clamp the pivot...a collet would be better. Slowly increase, then decrease the lathe speed. There are other methods. I'll see if I can find the thread(s) which discuss them.
     
  4. bruce linde

    bruce linde Technical Admin
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    i've read that you can also do what's called 'turning in a box'... where you make a face plate our of a piece of soft pine and a steel rod pressed into a hole. the wood face plate outside and face are trued, and then a recessed box is cut slightly small to the diameter of the gear on the arbor... once you drilled holes for the pin and arbor, the gear you've pictured would press fit into the wood. the other end would just stick through a steady rest.

    but... the masking tape coupler trick is the one i've seen mentioned more frequently.
     
  5. David S

    David S Registered User
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  6. Bruce Alexander

    Bruce Alexander Registered User
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    Actually I use a method that RC detailed in one of the MB Threads but I can't find it. It may have been part of a larger discussion.
    The method uses a brass rod drilled on one end to loosely accept bushings. You loosely fit a bushing to the pivot you want to hold and slip that bushing into the brass rod which has been chucked up already. It's not unlike a "Lathe Dog" set up. Attached to the bushing rod is some method to drive the gear. I use a rubber band stretched over a brass nail (through the brass rod). The rubber band then goes through the gear cut-outs and back around to the nail driver. Some type of washer(s) are slipped over the far end of the gear with the pivot you want to work on, followed up with a Steady Rest. I oil the pivot in the bushing and the part of the arbor held by the Steady Rest and spin it up. You could also use some type of masking tape as RC suggested instead of a rubber band. The original version of this method used a thinner brass rod "driver" which rotated into the gear spokes. I've found that the elastics are more adaptable to different gear/pinion setups.

    There are many other approaches, including the use of very expensive 8(?) jawed chucks. David S made a neat little tool to chuck "around" the gear.onto the middle of the arbor.

    You can do a search on "difficult pivot polishing" and find some old threads.

    Here is one:

    Polishing difficult pivots

    At the time, I was experimenting around with the use of a Plate Spreader as a Turns. I could get it to work, but not in all cases and certainly not better than the Lathe that I routinely use.

    I know there are quite a number of folks who really like their Shop-made "Turns".

    Rubber Band Drive.JPG
     
  7. Willie X

    Willie X Registered User

    Feb 9, 2008
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    If the pivot is in pretty good shape, I just polish them on a 3 or 4" muslin buff charged with Tripoli. Push the pivot into the buff using moderate pressure, as you turn the piece about 1/6 turn. One full turn should do it. This works very fast because the surface speed is about 50x that of the more usual methods. Keep a death grip on the wheel.

    You can also use a 'turn' and a hard leather buff stick charged with Tripoli. This will be slow but with more control.

    Willie X
     
  8. wow

    wow Registered User
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    The polishing wheels sold by Butterworths are great for these. Just mount in lathe and rotate pivot as the polishing wheel spins. The three different grades he sells will give you a mirror finish.
     
  9. Willie X

    Willie X Registered User

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    In post #6 the steady rest should be slid out to about 1/8" from the arbor/pivot shoulder. Otherwise could spell big trouble. Willie X
     
  10. Hudson

    Hudson Registered User
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    Here is one way that I use:

    arbor in faceplate and steady rest.jpg
    464419-67de77fd75da11e2539ac9e384f94ead.jpg
     

    Attached Files:

  11. Bruce Alexander

    Bruce Alexander Registered User
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    I have to be extremely careful with the abrasive disk approach. They work well, especially on large pivots but it's not easy to get into the shoulder area and so it is easy to create a tapered pivot. Others may be able to make them work just fine in a wide variety of situations. I can only comment on my results. I keep them handy though. They are a part of my approach in certain situations.
     
  12. fbicknel

    fbicknel Registered User

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    Great suggestions, all. Thank you very much.

    Looks like at a minimum I'm going to need a steady rest. I don't have one of those, yet.

    I made myself a cradle of the sort RC mentioned in post #2 from a piece of brass. It mounts in a chuck in the lathe's drilling adapter. I've used that with some success when the arbor is a bit longer or thinner and it feels wrong not to use the cradle.

    I might try Willie's buff method. The pivot is in pretty decent shape.
     
  13. TEACLOCKS

    TEACLOCKS Registered User
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    One of these on your lathe, and away you go.

    DSCF6502.JPG
     
  14. bangster

    bangster Moderator
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    Me with TAT and Willie: Steady rest.
     
  15. Bruce Alexander

    Bruce Alexander Registered User
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    #15 Bruce Alexander, Aug 26, 2019
    Last edited: Aug 26, 2019
  16. MARK A. BUTTERWORTH

    MARK A. BUTTERWORTH Registered User
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    This is exactly the situation where the Rollimat pivot polisher will accomplish what no other machine can do. Kindly check you tube to see the operation. We have both the hand cranked and motorized version for sale or rent.
     
  17. TEACLOCKS

    TEACLOCKS Registered User
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    I will not sell mine, But you can always find them on the -BAY.
     
  18. Bruce Alexander

    Bruce Alexander Registered User
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    I was really just wondering how much you paid for yours. I'll search the Bay, but please PM me with what you think is a reasonable price range if you would be so kind. Thanks.
     
  19. bangster

    bangster Moderator
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    Butterworth polishing disks in a dremel. Rotate the wheel by hand while polishing.
     
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  20. kinsler33

    kinsler33 Registered User

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    I've been using cruder arrangements, because this isn't a high-stress application. The major goal is to spin the pivot. So if you can make a small wood or metal face plate that runs true in your lathe or drill (I used a discarded automobile engine valve) and drill a hole in its center large and deep enough to accommodate the short pivot plus its brass boss (it can and should be larger, in fact) you can either glue or screw the wheel onto this small face plate. You'd need at least two screws with large washers. The wheel will have to be centered once it is placed on the face plate, and if you're using glue you'll want to avoid pressing hard on the long pivot.

    There are many variations, and I may have tried all of them, including one bit of inspiration that tragically included strong magnets and a steel face plate. Should have worked.

    I've posted several tricks, including one that employs two Timesavers "emery" buffs and no lathe at all (that one does work), here and there on this forum.

    M Kinsler
     
  21. shutterbug

    shutterbug Moderator
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    You can clamp on the pivot. Just be careful to have the arbor or other pivot supported in some way. It's best, of course, to do the pivot that you clamped on last ;)
     
  22. D.th.munroe

    D.th.munroe Registered User

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    Does anyone use these and a runner on the pivot end for that?

    15670026300881796480918321154713.jpg
     
  23. R. Croswell

    R. Croswell Registered User

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    OK for larger American pivots. Don't try it on tiny hardened French clock pivots unless you like replacing pivots.

    RC
     
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  24. Kevin W.

    Kevin W. Registered User
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    I have done a few of them by hand, takes less time.
     
  25. Jerry Kieffer

    Jerry Kieffer Registered User
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    My personal method is to hold the wheel in either machinable jaws or reverse jaws and support the pivot in a half round runner mounted in the tailstock per first photo.

    The ball bearing rest in the tool holder holds a tool for filing/polishing and or burnishing per second photo. This assures that the pivot will be straight and round and not tapered.

    Jerry Kieffer

    fullsizeoutput_41c.jpeg fullsizeoutput_41d.jpeg
     
  26. fbicknel

    fbicknel Registered User

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    Hey, thanks, Jerry. How did I miss using my 3-jaw chuck for this? *shaking head*.... and the rest is a great idea, as I have caught myself a little off on the parallel, but I keep practicing.

    And what's that you're using for the abrasive? Is that a homemade burnishing tool?
     
  27. Jerry Kieffer

    Jerry Kieffer Registered User
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    I often buy lots of tools at regionals etc without knowing origins unless marked. Without finding the exact tool in the pile I grabbed it from, I believe it is a commercial burnisher.
    Either way its a burnisher.

    Jerry Kieffer
     
  28. gmorse

    gmorse Registered User
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    Hi fbicknel,

    Looks like a Swiss one, probably Grobet or Glardon in Vallorbe.

    Regards,

    Graham
     

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