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Pivot polisher

David Robertson

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RJ,

If the arbor is long and stout enough to be well supported in the headstock chuck or collet, it is easier to file and burnish from underneath the pivot because you can see what you are doing. If it is a thinner or poorly supported arbor at the headstock end, it is necessary to support the tailstock end in some sort of bed. In this case, you must work from the top because the support is in the way of getting to the bottom.

If you are working from the bottom, the acute angle will need to be one way. If you are working from the top, the acute angle will need to be the other... thus left and right handed pivot files and burnishers.

Files and burnishers with rectangular cross sections prevent this problem but must be in very good condition in terms of a square corner.

I will continue to recommend some of the basic clock repair books to you. Most of the questions you ask are covered there..

David
 

ticktock

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Polishing uses abrasives to give a flat, finely finished surface to the pivot.
Burnishing uses a very fine file (pivot file) to “remove” metal, if necessary to make it smooth, and then a burnisher to “move” metal to squash down any high places into lower ones. It also compacts and smoothes the finish of the pivot.
I am confused. You say Burnishing uses a pivot file to remove metal and then a burnisher to move metal. Are burnishing and burnisher two different steps? Then where does pivot filing fit in? I thought one does pivot filing then burnishes, which means polishing. Please explain.
 
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Charles E. Davis

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I was using the term burnishing in opposition to polishing as processes.
In burnishing you are working on pivots that can be cut by a file. So; if necessary; the file end on a double ended File/Burnisher is used first to remove metal and then the burnisher "moves" metal to give the final finish.
In polishing, abrasives of various grades are used to remove metal until a very fine finish is achieved. It is used on very hard pivots.
 

KyleG

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Bringing this to the top for ref to "Pivot Work" thread by al_taka
 

Charles E. Davis

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Another thread on Pivot Work suggested that I reactivate this thread. The pictures are on the first page but the entire discussion was very interesting.
Charlie Davis, La Verne, cA
 

Charles E. Davis

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I have made them by using a hollow plastic coffee stirrer as a "core" and packing JB Weld around it from both ends of each of the holes for runners. JB Weld can easily be drilled out to the size of your runners. It works fine.
You will need to be able to tap the holes for the set screws.
The runners can take a bit of time. The first ones I made were done with brass tubing that I sweat soldered bushing in. Then I sawed off half of the end to make the runner. The final depth of the runner is best done with a file.
Charlie Davis, La Verne, CA
 

bangster

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A question for Charles: Is this device better for pivot work than a lathe, and if so why?

bangster
 

eclecticbeat

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Charles,
As strange as that first sounded to me, I can see where that could work. How long did they hold up for you? I can tap the hole but I never tried J.B weld. It actually can be drilled, tapped plus be strong enough to hold a set screw without falling apart in this application? If it can I’ll no longer wonder why some swear by it.

Quote:
Posted by dutch 07:38:50 14 Aug 2005
I really like the looks of your pivot polisher and am going to make one but I have never understood why chucking up the arbor in a collet on the left side and supporting the pivot on the right side as shown, but held in the tailstock of a lathe is not recommended.
I have never been satisfied with my pivot polishing but have never seen anyone else do it and maybe I am expecting too much, and after reading about using a bow to turn the arbor I suspect I have been turning too fast.
Dutch

I am not sure why an owner of a lathe with a tailstock would need the hinge or the hinge barrel bushing parts. Could it be as easy as unplugging the motor and use a bow or squeegee?
 

Charles E. Davis

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JB Weld has metal mixed in the epoxy and is more than adequate to position the runner and hold the set screw. There is very little force to move the runner down where you are working compared to the surface holding the runner. All it really has to do is support the runner. I have sometimes wondered if you would need a bushing at all. The set screw would bottom the runner and line it up, it seems to me. Much like a pivot is spring loaded in a bushing hole. It will find its resting place.
Any lathe could be used as a dead center lathe, which is what the turns are. And the version made from a hinge is functionally exactly like the turns, except the width adjustment can only be made with the runners, and not with moving the tail stock end.
The advantage of the turns in polishing pivots is the ease of set up and the control of the operation. A short demo with a new student gets them started. I would be very apprehensive if I was turning a student loose trying to polish pivots on a lathe!
Charlie Davis, La Verne, CA
 

eclecticbeat

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Thanks Charles,
It might take me a week or two but I’ll try it both ways and post a picture. I had to vacate my shop (a.k.a the Kitchen) for the holiday and need to find my notes on the pivot sizes I have to deal with. I think they’re 1.5mm and 1.8mm but better double check them. I guess I really should pick up a metric micrometer. Mine’s English and I’m not sure how far the conversion is off.
 

harold bain

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At the request of a member, I am bringing this thread up to the top again. There are pictures of Mr. Davis's hinge pivot polisher on the first page, for those interested:thumb:
 

Rollerpen

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With the change in the board software, this link old ref::http://nawcc-mb.infopop.cc/eve/forum...1/m/4241090751,
no longer appears to be available.

Is it possible to resurrect this thread. I would love to review it.

Ken
 

harold bain

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Ken, I'm not sure what that link would have had, but it is not likely to be restorable. Charlie's pictures and description of his hinge tool are still there on the first page of this thread.
 

Kevin W.

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Since this thread is read frequently, could it be a sticky at the top of the message board , like some of the other ones are?
 

harold bain

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Could be easily done, Kevin. What do others think? Should we pin this thread to the top?? I could edit out any posts that don't add to the value of the thread, such as this one.
 
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shutterbug

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Personal opinion, but I don't think it merits the same 'honor' as the other pinned information. This one can be found by a search fairly easily, and the title pretty accurately describes what it's about. While the tool is useful, I'm not sure we'd want to give the impression that it's 'state of the art' :)
 

celticprince59

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Hi S/B, Maybe you are missing the point of it being so simple beyond belief, that it warrants a "Place of Honour". It shows how ingenious people can be when it is needed. I am sure 30 years ago to have the money to buy a manufactured one was not that easy, with children, mortages etc). You could also be correct in your way of thinking, so maybe it would be great to see what the rest of the folk think.
Keep up with the debating way of questioning.

Andy
 

bangster

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Not an issue of "honor", but of breadth of general interest. This thread can easily be found by a search, for those interested in doing so. Especially if there's one or two "alias" threads like the one I'm about to start.

bangster
 

shutterbug

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There you go bang! That makes a lot more sense than pinning it to the top. I can envision having to wade through 50 pinned threads some time in the future to find the recent ones, if pinning becomes a precedent/habit :)
 

Kevin W.

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I guess most people don,t think my idea is a good one.:(
I understand we do not want too many posts as stickies.
 

shutterbug

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The OP, Charles, was last seen here in April, 2019. I hope he's doing well and will check in again soon.
 
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