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Pivot Polishing

sjaffe

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Dec 25, 2012
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Back to basics: I am curious how others polish their pivots.

Currently I use a lathe and first use a hard Arkansas stone (per Steven Nelson's tid-bit), then a burnisher (per LaBounty's article). I do not support the end of the arbor. I am considering something akin to a Jacot or drilled brass half round to support the pivot. How do you do it?

Stan
 

Rob P.

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Dec 19, 2011
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I support the pivot in a brass half-round in the tailstock. I have several with different sized "half-holes" for this job.

From there, I use different things depending on what the pivot needs done to it. Files nad stones to remove material, a flat burnisher, emery/crocus cloth sticks for general rough polishing, and a ruby slip for final polishing. Not every pivot gets all of the above but every pivot gets the ruby slip used on it as the last polishing step.
 

shutterbug

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For most pivot work, I use the pivot tool you can get from most suppliers. It has a very fine abrasive end and a burnishing end. Made for either above or below the pivot polishing. I like the 'below' model so I can see what I'm doing. I don't support pivots unless they are very thin. They are quite capable of withstanding the small amount of force I apply to them during polishing. For speed, I chuck them in an electric drill on slow speed and work on them at eye level to be sure I don't taper them. Putting them in the lathe takes more time than it's worth. I'd never attempt to replace a pivot with a drill, but for polishing it works just fine.
In the occasional situation where you have to chuck on the pivot itself, support is required! Otherwise you'll twist the pivot right off the arbor. I would not recommend the drill for that use! :)



I think I'll move this discussion over to the Clock Repair forum. It's not specific to 400 day clocks, and we'll get more information over there :)
 

Willie X

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Feb 9, 2008
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I do nearly all of my pivots using a 4" musslin buff charged with Tripoli. This is on what jewellers call a dust collector. Not much different from a bench grinder but it has threaded tapered spindles on the motor to take the soft uncounted toy buffs. These spindles are available separately from jewelry supply houses. This method is very fast, as the surface speed of a 4" buff is about 100 times greater than a pivot turning in a lathe. It's also risky until you develop your technique.
Willie X
 

AJSBSA

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Nov 24, 2009
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Everybody has their preferences I started out using the lathe and even made a Jacot tool for my Cowells lathe but after a while I realised that spinning the pivot under power in a lathe was in fact potentially very harmful to the wheel one wrong move could easily destroy it.
After a bit of research and some practice I discovered that 95% of the rough pivots I encountered could be sorted quickly and easily by hand I might invest in or make a Clockmakers throw at some point but for now this is all I use, the cut out is important it gives clearance for the warning pin. You have to rotate the wheel in one hand while moving the pivot file forward with the other after a bit of practice you will be surprised how quick it is to get a perfect pivot, use the honing oil with the file/burnisher, finish off with a wood stick charged with metal polish.

Pivot-P-001.JPG Pivot-P-002.JPG
 
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Jay Fortner

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Feb 5, 2011
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I use a leather buff that I make from and old belt and punch out a 1" disk using a hole punch. Then punch a hole in the center to mount it on a foredom(dremel)arbor. If your center hole is off a little just hold the spinning buff against the side of a grinding wheel to true it up. Charge the buff with white rouge and just go around the pivot by hand. It puts a mirror finish on them.
After you get it all polished up and shiny then wipe the pivot with the corner of a rag soaked in carb cleaner. I use the same method to polish pallets.
 

hggraham

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Apr 6, 2009
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I use a Rolleimat (Swiss). Yes it's expensive, but is probably the last tool I'd do without. No, it doesn't burnish, but the results are better than 99% were from the factory. It's fast, doesn't leave a taper, and does arbors with levers attached.
 

Dave T

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I use a leather buff that I make from and old belt and punch out a 1" disk using a hole punch. Then punch a hole in the center to mount it on a foredom(dremel)arbor. If your center hole is off a little just hold the spinning buff against the side of a grinding wheel to true it up. Charge the buff with white rouge and just go around the pivot by hand. It puts a mirror finish on them.
After you get it all polished up and shiny then wipe the pivot with the corner of a rag soaked in carb cleaner. I use the same method to polish pallets.
I like this idea, think I'll try it.
 

shutterbug

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Very similar to the pivot polishing kit that Butterworth Clocks sells. His has three grades of hardness, so you can work with any degree of roughness in the pivots.
 

Jay Fortner

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Not even close shutt. Those wheels that Mark sells are rubbberized,impregnated with carbide grit,most industrial supplys sell them. They're more for fine grinding than polishing and must be used with a lathe or your drill motor or you risk the chance of grinding a flat spot. Those would be good to smooth the scoring out then finish with the white rouge on leather or muslin. If using them for polishing pallets care must be taken to not change the impulse angle or remove too much material.
 

Tinker Dwight

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Oct 11, 2010
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I checked a few videos out on the rollimat polisher.
What a nice machine.
Way out of my budget though.
The only problem case might be a warning wheel.
Tinker Dwight
 

bangster

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I use the lathe. Polishing with 3 increasingly finer popsicle-stick buffs, finest one is crocus.
File when necessary first.
Don't burnish any more. Probly should take it up again.
 

hookster

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Jan 14, 2011
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I do similar Bang, but finish with Simichrome on a popsicle stick (by the way useful when one encounters plated Hermle pivots). I do have two burnishers, but seldom use them either.
I use the lathe. Polishing with 3 increasingly finer popsicle-stick buffs, finest one is crocus.
File when necessary first.
Don't burnish any more. Probly should take it up again.
 

Willie X

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Feb 9, 2008
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In post #4 "soft uncounted toy buffs" should have read "unmounted buffs". Never trust your auto-complete.
Willie X
 

Rob P.

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I use the lathe. Polishing with 3 increasingly finer popsicle-stick buffs, finest one is crocus.
File when necessary first.
Don't burnish any more. Probly should take it up again.
Like I said above, not every pivot gets the full treatment. I don't burnish unless I've take material off to refresh the pivot surface. I'm pretty positive that the pivots were burnished at some point in the past and don't need it again. So for most jobs, it's just a polish.

I use the lathe because I have a muscle twitch issue and don't need to be breaking pivots. With the lathe, the parts are held securely and the tailstock rod keeps any minor problems on my end from causing a catastrophe to the clock parts.
 

Tinker Dwight

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I looked at the rollimat again and believe I see a
serious flaw. I noticed a funny twinkle from one
of the pivots as he was rotating it.
If the cut was deep, it would tend to make an unround
pivot. As the first cut went into the back support, ( can't remember
the French name for it ) it will make a sudden change in thickness.
That will translate across the pivot to a flat spot. As the new flat spot
rotates, it cause another flat spot. Since the back support is
V shaped, it creates two flat spots and so on. I believe they might
even out over time but how much metal would one need to remove
before it got truly round again. This is a similar problem for the
manufacture of drill rod. They tend to make 3 lobe surfaces with similar
grinding methods.
I think a lathe would produce better results.
Still, I was looking into how one might make one themselves.
Finding the carbide wheel is tough but I think I found what
to use. They make wheels like that for shearing metal strips.
They are round to .001mm and have a nice flat surface.
One could rough it up a little with a diamond stone.
Tinker Dwight
 
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Jay Fortner

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Tink,I've always thought that you could use a bearing race. They are not carbide but very hard and once you made the hub to mount it on it could be easily replaced if or when it wore out.
 
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Tinker Dwight

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Oct 11, 2010
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Good thinking Jay.
I think it would be better with some type of lathe
rather than the support shown in the rollimat.
Doesn't work as well for crutch arbors but then they
don't need to be a round as wheel pivots.
Tinker Dwight
 

Jay Fortner

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Feb 5, 2011
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The best way to burnish anchor pivots is with a very small drill chuck. Oil the pivot and lightly tighten the chuck onto the pivot and twist by hand. It does a satisfactory job of burnishing and keeps them round. On pivots that are only a little rough but not scored I use a pair a smooth jawed pliers and lightly squeeze them on the pivot while spinning the arbor with my other hand. Makes them smooth enough to pass the fingernail test. It's also a good way to burnish strike lever pivots.
 

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