Smooth Broaching New Bushings

[Michael Linz]

OK, I know there are many threads on the pros and cons of smooth broaching, but in my searches on the Forum, I've only found a little on the pros and cons of smoothing new bushings that are otherwise fine as is. If you do use a smooth broach, the broach should be oiled with the same oil you plan on using with the movement, and the method described by David LaBounty, in his article titled "Burnishing" is to wallow the tool in the bushing: Burnishing. From the various threads I've read, it almost seems to be a matter of personal preference regarding the science whether or not to broach and whether or not the bushings are new or original. Any articles that might help me to make a final decision on which direction to go?

Presently, I only broach new bushings when it is necessary to make the ID large enough to accommodate the pivot properly (5 degrees of movement). This happens when I have to choose between a bushing who's ID is slightly too small as opposed to the next size up which turns out to be too large. Presently I do not smooth broach new bushings that require no adjustments. I read from several clock makers that they never broach at all and seem to be happy if the bushing ID is "close enough" without binding.

As my experience and knowledge in repairing clocks progresses and grows, I especially think it is appropriate to broach a new bushing (as outlined in the previous paragraph), especially the case when it is necessary to file and polish the pivot due to uneven wear and ridges. Any thoughts?

 

[bruce linde]

first off, ANE ('ain't no expert')

that said... i bush and then check the spin between the plates just to see. if the gear/arbor turns a greased pig sliding on ice, that one's done. if it turns a few times and stops more abruptly than the pig, i might smooth broach just a smidge to achieve slip-n-slide-i-ness.

i don't think there's a set rule, as each pivot, pivot hole, plate and busing are all going to be unique.

at least that's how i look at things....

 

[howtorepairpendulumclocks]

In my experience soothing broaches are not needed. Because a cutting broach cuts with a very negative effective top-rake, the cutting action is both cutting and compressing (work-hardening/burnishing) anyway. I would say, save your money and time. I do however find that demurring the hole with 0000 (4 0s) steel wool on a piece of finely tapered peg wood really cuts down on problems with small burrs picking up and causing a clock to stop after a few months of running. Obvs you need to clean the hole following this. Hope this helps. As another correspondent says, the mobile should be very free in the frame, falling from shoulder to shoulder when the frame is inverted. Any hesitation should be investigated as it will bite back...

 

[NEW65]

I think there are many of us that do not use smoothing broaches - I always use them and also use them on worn holes to make the holes rounder which can make noticeable improvements. I never used to use the smoothing broaches but since using them on newly fitted bushings (just after using the cutting broaches) and on slightly worn pivot holes, I have had much better results.

 

[John P]

We smooth broach every bushing new or old for several reasons. Are all new bushing perfect with no machine defects?? NO

If the broach stands up crooked, it tells you that this bushing is not installed correctly.

There may be a burr in the bushing from someone dragging a wheel in during reassembly and scratching the plate.

All new bushings should be chamfered slightly on the inside for clearance in the shoulder area of the pivot thus the need to smooth broach that bushing.

Why skip a critical part of clock repair that takes only a few minutes?

To me, there is much satisfaction in rebuilding a movement and not having to go back into it. And every step of the process is important.

JohnP

 

[Robert Horneman]

We smooth broach every bushing new or old for several reasons. Are all new bushing perfect with no machine defects?? NO

If the broach stands up crooked, it tells you that this bushing is not installed correctly.

There may be a burr in the bushing from someone dragging a wheel in during reassembly and scratching the plate.

All new bushings should be chamfered slightly on the inside for clearance in the shoulder area of the pivot thus the need to smooth broach that bushing.

Why skip a critical part of clock repair that takes only a few minutes?

To me, there is much satisfaction in rebuilding a movement and not having to go back into it. And every step of the process is important.

JohnP

I agree with you 100%

 

[R. Croswell]

New bushings have straight sided holes. The original pivot holes had straight parallel sides. Smooth broaches are tapered. If the bushing is installed properly (perpendicular to the plate) and fits the pivot it does not need to be smooth broached. Forcing a tapered smooth broach into a straight sided hole, or "wallowing out" the hole destroys the parallel relationship between the pivot and the bushing. I use Bergeon bushings and have yet to find a defect. Of course if the bushing is not set perfectly perpendicular to the plate, as can often happen with hand bushing (and some other) methods, Wallowing the hole may be one way relieve a binding problem.

When a bushing has to be opened with a tapered cutting broach I always follow with a tapered smoothing broach. Bushings are already supplied at the proper hardness; I seriously doubt that ordinary broaching does much to work harden a manufactured bushing. One has to ask why would anyone want to make the bushing any harder? Many here have observed that bronze bushings (harder than brass) tend to cause excessive pivot wear.

RC

 

[John P]

Smoothing broaches can be used without wallering out a hole. Put a drop of oil on the broach and drop it in the hole. Give it a couple of spins and do both sides. The outer edge of a new bushing is what needs smoothing. There will be no damage to the bushing.

johnp

 

[shutterbug]

I have never used smoothing broaches. The pivot only touches a very small area of the bushing, and after a week on the test stand, that tiny area is going to be smooth. I'm sure the factory never smooth broached after drilling or punching the holes. Smoothing a new bushing might feel good, but I don't think it does any good. Conversely, it probably does no harm ... so whether you do or don't is just a choice.

 

[Michael Linz]

We smooth broach every bushing new or old for several reasons. Are all new bushing perfect with no machine defects?? NO

If the broach stands up crooked, it tells you that this bushing is not installed correctly.

There may be a burr in the bushing from someone dragging a wheel in during reassembly and scratching the plate.

All new bushings should be chamfered slightly on the inside for clearance in the shoulder area of the pivot thus the need to smooth broach that bushing.

Why skip a critical part of clock repair that takes only a few minutes?

To me, there is much satisfaction in rebuilding a movement and not having to go back into it. And every step of the process is important.

JohnP

In any cases I too chamfer on the inside of the bushing if I feel it is warranted (most cases).

 

[Jerry Kieffer]

I suspect that Tapered broaches and smoothing broaches has shortened the repair life of more pivot hole sizing repairs than any other single tool. Not to mention the increase in friction that they cause.

Jerry kieffer

 

[D.th.munroe]

Unless your doing it seriously wrong I don't see how it could cause increased friction.
You can rebush some clocks, usually cheaper ones perfectly and when weight or power is added the plates shift and your perfect pivot holes are all off, unless you can somehow get the plates into the loaded position and rebush, using a tapered broach from each side can be an answer, though not the only one.
And what do you do about clocks that were originally made with hand tools holes all broached in the beginning?

There is also a tendency of a 5 sided broach if the 5 sides are equal and your making the hole much bigger, to sometimes not cut a round hole, it ends up a bit flower shaped. Which may have been one reason for smoothing broaches.
If you use a hand broach in a power tool you can prove this, though I don't recommend it.

 

[D.th.munroe]

Also here is a tool some masters recommended after broaching for "burnishing" the pivot holes more parallel.
Putting the hardened and highly polished steel burnisher through the pivot and firmly dragging it around the circumference of the hole keeping the brass firmly against the plate. (with protection for the plate, paper or something) .
Of course it can't be used everywhere
I thought it should go somewhere here for opinions.

 

[Jerry Kieffer]

Unless your doing it seriously wrong I don't see how it could cause increased friction.
You can rebush some clocks, usually cheaper ones perfectly and when weight or power is added the plates shift and your perfect pivot holes are all off, unless you can somehow get the plates into the loaded position and rebush, using a tapered broach from each side can be an answer, though not the only one.
And what do you do about clocks that were originally made with hand tools holes all broached in the beginning?

There is also a tendency of a 5 sided broach if the 5 sides are equal and your making the hole much bigger, to sometimes not cut a round hole, it ends up a bit flower shaped. Which may have been one reason for smoothing broaches.
If you use a hand broach in a power tool you can prove this, though I don't recommend it.

Assuming your post is in response to mine, I will try and answer in order

(1) I always suggest returning Movements to the original state, Another words the same size straight round pivot holes as from the factory.
If a pivot must be reduced in size for proper finish, I then suggest reducing the bushing hole the same percentage as the pivot.
Under these conditions, spring loads and weight loads typically do not effect operation or few would have ran from new.

(2) Competent Makers like manufacturers drill holes to the desired size and do not broach them. Of course there will always be an exception some place.

Ok , not in order, the friction part last.

The issue with broaches and smoothing broaches is that in real life, it is virtually impossible to hold them 90 degrees to a plate when broaching.
This in turn produces much greater tapers than the taper of the reamer itself. So no matter where the taper is applied, even if from both sides with a high spot in the middle, it assures that the pivot will ride on the highest point making metal to metal contact creating max friction and wear.

When competent manufacturers design instruments or Horological movements, the goal is have the rotating member of a bearing to ride on a oil film. In horological movements where the plates are very thin, this typically only happens in the upper half of the movement assuming it was intended. Thus the straight round holes to give the greatest chance even if its only the upper half decreasing friction.

This has been a ongoing discussion for decades. Years ago I did a presentation on this subject at the St Louis regional and may still have the magnified photos showing the difference between broached and straight pivot holes during movement operation if anyones interested.

Jerry Kieffer

 

[D.th.munroe]

Well not in whole in response to you Jerry The friction part yes but otherwise was in general.
My job is to restore timepieces to their original state as you say, and although I did do alot of handwork and developed hand skills I use a mill to do the majority so it's easy to keep it all correct.
It still completely ignores hundreds of years of successful handmade clocks and hand clock repairs that would be in your view incompetent?

 

[bruce linde]

i take jerry's points and can visualize straight vs. tapered sizes. i'm also thinking about the back pivot on the fusees i've seen, that always seem to be grooved... if the pivot hole were tapered so the high part was in the middle, that might explain it.

i also see D.th.munroe's point... and am thinking about my 'new' 1780-ish tall case clock, and wondering how the jerry' keiffers of the first half of the 1800s (and prior, i.e., willard, for example) solved/addressed this problem? what tools did they have to guarantee perfectly straight holes? and... did they not broach (smooth or cutting)? i thought broaches were a historical thing?

 

[Jerry Kieffer]

Well not in whole in response to you Jerry The friction part yes but otherwise was in general.
My job is to restore timepieces to their original state as you say, and although I did do alot of handwork and developed hand skills I use a mill to do the majority so it's easy to keep it all correct.
It still completely ignores hundreds of years of successful handmade clocks and hand clock repairs that would be in your view incompetent?

D and Bruce
Makers of early movements drilled their holes when constructing a movement. The following is an example of a 1700`s bow drill.

1700s French Bow Hand Drill | Etsy

Offered for sale is a museum quality French bow hand drill circa mid 1700’s. I have seen a similar ones in antique collectible books. A bow with leather strip would be wrapped around the center handle of the drill. By pushing down on the wooden handle and moving the bow in a sawing type motion the

www.etsy.com

Plates were much thicker than today and they made their own spade type drills that were of course far easier to make than a tapered broach as we know it today that really make a mess in thick plates. Thus whatever hole size they needed, they simply made the drill and drilled it. I have not seen any tapered pivot holes in any of the early movements that I have worked on that appeared to be original.

Competent or incompetent would be a personal perspective thing. When you encounter a movement that has ran a 100 years and you return it to its original state, you can be assured of a likely long service life. When you change that scenario you now have a unproven condition. They had the ability to drill rifle barrels round, straight and to size, making the drilling of a movement plate and or a repair a snap.

I should add that for my part, I just happen agree with the approach taken by the majority of the makers and manufactures of the last 300 years or so.

Jerry Kieffer

 

[D.th.munroe]

Jerry I was referring to your statements that "competent manufacturers" and "competent makers" do such.
On the rest I will only say, while you are very knowledgeable, you need to study a bit deeper or more on how it was done in the 1700's.

 

[Jerry Kieffer]

Jerry I was referring to your statements that "competent manufacturers" and "competent makers" do such.
On the rest I will only say, while you are very knowledgeable, you need to study a bit deeper or more on how it was done in the 1700's.

Actually you bring up a good point.

Unfortunately, we really do not know a lot about how the better quality work was done during the cottage industry days, since many took their work procedures to the grave as it was their lively hood.

The early movements that I own and have repaired/inspected over the years, have rather thick plates where original pivot holes are straight and round.

Because of the thickness of the plates, its easy to observe work techniques and characteristics such as holes.

Since these movements have provided dependable service for so many years, I see no reason not to attempt to duplicate what has been done when making repairs.

While there will always be successful and unsuccessful ventures, from my point of view the successful ones that provided and do provide something of long service life are "competent".

Jerry Kieffer

 

[D.th.munroe]

I should make it clear, I'm not arguing a point for waisted pivot holes!
The point is most made that parallel hole you see with a broach.

There is actually contemporary literature on how it was done by some of the better makers back then.

As well as even more recent.
Accurate holes with smooth walls suitable for a bearing surface in a precision instrument wouldn't be drilled to size, it would be drilled under sized and bored and/or reamed to size. Maybe not in mass manufacturing but for a precision instrument.

 

[howtorepairpendulumclocks]

Just saying' but it is not possible to return anything to a former conjectured state. The arrow of time moves in one direction (at least where this kind of mechanical problem is concerned). Whatever we decide to call it, change is change and it is new work. )

 

[Thomas Sanguigni]

I'm in the JohnP camp. The only thing I do not do is taper the inside of the bushing. I was always taught that could cause binding. A smooth plate on the inside lets the gears turn more freely.

A smooth broach can also help you determine if a bushing is a bit dog boned. Sometimes magnification does not show that small elongation of a pivot hole. So, I insert the smooth broach lightly and hold it up to the light. Bingo, you have your answer.

 

[Jerry Kieffer]

I should make it clear, I'm not arguing a point for waisted pivot holes!
The point is most made that parallel hole you see with a broach.

There is actually contemporary literature on how it was done by some of the better makers back then.

As well as even more recent.
Accurate holes with smooth walls suitable for a bearing surface in a precision instrument wouldn't be drilled to size, it would be drilled under sized and bored and/or reamed to size. Maybe not in mass manufacturing but for a precision instrument.

In Horology there seems to be two ways of doing things. Those that are often done by Makers and manufacturers, and the methods often suggested by repair publications, education and individuals.

Personally I feel that makers and manufacturers have a better track record, so in repair, I return things as original as mentioned.

We each have our own reasons and methods, but I am always happy to demonstrate any comment or suggestion I may make.

While such things are not worth arguing over, they can be interesting to debate and demonstrate, especially if you get the other person to buy the beer.

Jerry Kieffer

 

[Thomas Sanguigni]

Jerry you make a good point about manufacturers and how they approached their clocks. Have you ever read how Chauncey Jerome recommended cleaning clocks? It is a real gasser. I think we are a different point than the preceding clocksmiths. These movement are now over 100 years old or more.

There are way more problems for us to solve and way more poor repairs to fix.

Can you post any of your St. Louis presentation photos? I would be interested.

 

[R. Croswell]

This "debate" has unfolded here several times in the past and usually ends the same way - that is, that any way other than "one way" implies that the repairer is incompetent, or at least does inferior work and should change his/her methods. The debate usually ends with an agreement to disagree on alternate methods, or it just ends with several individuals knowing that they are right, and everyone else not so sure one way or the other.

I can't settle the debate of whether tapered broaches should or should not be used and I'm not going to try but here are a few things to think about.

1) Unless a machine (and a clock is a machine) using sleeve bearings has some way to self-align that bearing [bushing] to be parallel to the pivot or shaft it will be impossible for the pivot and bushing to have perfect contact along the length of that bushing/pivot pair when examined at the micron level. For that reason such machines, especially older machines, required a "brake in" period.

2) Obviously, a bearing [bushing] with a tapered hole, even if tapered from both ends, will initially have a small area of contact with the pivot. Eventually, the pivot and bushing will wear in for a good running fit. That creates two unavoidable issues: The debris generated during the wear in process, and the high initial wear subtracts from the life of the bushing. Good reasons for a follow up cleaning after a year or two of running.

3) Something that isn't often considered is the alignment with the opposite plate. It should be clear that any misalignment between plates will cause the pivot to not be parallel to the hole in the bushing even if hole in the bushing is perpendicular to the plate and has straight sides. I think this is more of a problem with inexpensive clocks and those that have been subjected to less than the best care over the years. It also points out the need to be as precise as possible when centering a bushing.

4) A bushing that is slightly tapered from both ends can better accommodate any small misalignment between plates.

5) Especially with ordinary and inexpensive clocks, like most of the ones we see in this forum, striving for, or demanding an ultra high level of precision may give the repairer a personal pride, but probably isn't necessary, and can raise the bar so high as to discourage those who are only interested in pursuing clock repair as a hobby and perhaps feeling an even greater pride is seeing a $35 flea market clock run again.

Finally, I would contend that no bushing installation is perfect at the finest detail, but some are more perfect than others, some last longer than others, but even some not so perfect jobs my accomplish one's goal of making a junk clock fun again even if less than a hundred years.

RC

 

[Jerry Kieffer]

Jerry you make a good point about manufacturers and how they approached their clocks. Have you ever read how Chauncey Jerome recommended cleaning clocks? It is a real gasser. I think we are a different point than the preceding clocksmiths. These movement are now over 100 years old or more.

There are way more problems for us to solve and way more poor repairs to fix.

Can you post any of your St. Louis presentation photos? I would be interested.

Thomas

I found a couple.

This happened many years ago, but some of the most interesting discussions come up at regional banquet dinner tables. This night there was a very heated discussion over the use of broaches and smoothing broaches by a couple of guys who often butted heads. However I was to dumb at the time to just enjoy the discussion and had mention something about pivots running on an oil film in some cases. At that point, guess who should have kept their mouth shut.

To make a long story short, the next year I did a presentation on Movement Characteristics that in part covered the possibility of Horological pivots running on a oil film.
From about the time interchangeable parts were manufactured (1860 or so) technology had progressed to the point where having a rotating member of a bearing assembly ride on a oil film was a goal to shoot for. The question was, was it possible in a horological movement considering the thin plates and various loads on various pivots. Again to avoid pages of discussion, it can be demonstrated in the upper half of a typical movement of reasonable construction quality.

The presentation involved a movement that did have wear that was disassembled during the presentation. An original pivot hole was measured from the arbor in front of the escape wheel and then bushed. The bushing was then broached with a taper broach so that the exit hole measured the same Id as the original plate pivot hole and the movement was reassembled. The pivot was only polished since it appeared to have no wear.
The movement was then fully wound and was running when the first photo below was taken of the installed bushing after lubrication. The photo shows metal to metal contact of the pivot at the arrow tip with no parallel flat surface for lubrication support.

At this point the movement was again disassembled and the bushing replaced. However this time the ID was reamed straight and round the same diameter as the original. The hole was also reamed parallel to the Arbor/pivot when assembled. Again, it was assembled, fully wound and the second photo below was taken while running. In this case, it can be easily seen that the pivot is suspended by lubrication without metal to metal contact.

Of course, this is not achievable in all cases for all pivots for many reasons, but a very worthy characteristic to retain when making repairs. Or at least in my opinion.

Jerry Kieffer

 

[R. Croswell]

In this case, it can be easily seen that the pivot is suspended by lubrication without metal to metal contact.

Jerry, that's an interesting observation but needs one more step to verify that the pivot in the second picture is really "suspended by lubrication". We are also looking at two different situations (one pivot is in a tapered hole and the other in a parallel-sided hole). It would be expected that a pivot in a tapered hole (the first example) would be supported by a very small contact area at the small end of the bushing and that avoiding metal to metal contact would be difficult to impossible under such conditions.

One cannot really tell from the 2nd. picture whether the end of the pivot is "suspended by lubrication" or just centered in the hole by other means. If your explanation for what we see is correct, the next logical step would be to disassemble the plates and flush all the oil away with solvent and reassemble just as before. If the pivot was actually supported by lubrication before, as you suggest, then we should now see metal to metal contact similar to the first photo. If the pivot is truly suspended by lubrication, then there should also be a very high electrical resistance between the pivot and the bushing.

I rather suspect that for a pivot at rest in either a tapered hole or a hole with parallel sides, especially while under load, that the pivot would displace all or most of the oil at at the point of contact and metal to metal contact would likely be unavoidable. I would expect the thickness of any oil film remaining between these parts would be far too thin to see at this level of magnification. But repeating the demonstration with all oil removed would be informative. Not withstanding the above, it should be self-evident that a perfectly aligned straight pivot in a parallel-sided pivot will be better supported than the same pivot in a tapered hole, at least initially.
'
RC

 

[bruce linde]

funny, i was thinking about this issue in the wee hours last night.

conceptually (and ideally), pivot holes with straight/true sides, perfectly lined up between plates, with perfectly formed and aligned pivots and the ideal balance between pivot holes being too tight or too loose for a particular gear, and factoring in how much sideways torque ends up pushing pivots against a particular side of a particular pivot hole would make for (essentially) as good as one could get.

but...

clock movements are designed for a certain amount of slop... and so are pivots and pivot holes. the amount of tolerance is going to vary for each arbor in the train, based on how much power/stress it's under... yes?

how does one insure perfect alignment of plates? i could see this happen using lasers (for example), but i'm working on a movement now where the front plate slips onto three of the four posts perfectly... and the fourth post has to be nudged a bit to snap into the hole in the front plate. i don't think that's torquing the alignment, but who knows? maybe some kind of set of long gage pins (long enough to go through matching front and back plate pivot holes, with L-bracket-like ends so you could check for square?

even if we were able to insure all of the pivot-related lines were true and aligned... what happens when you fasten a movement to a seatboard or back of case? we don't really use torque wrenches to insure that things aren't too tight (or too loose)... and in fact sometimes tightening down a movement too much makes it stop as the plates get pulled slightly.

everything jerry says makes sense to me, and i'm sure every movement he works on is a million miles closer to ideal standards than anything i touch... but i'm still thinking there's a sweet/balance spot somewhere in-between.

 

[Jerry Kieffer]

Jerry, that's an interesting observation but needs one more step to verify that the pivot in the second picture is really "suspended by lubrication". We are also looking at two different situations (one pivot is in a tapered hole and the other in a parallel-sided hole). It would be expected that a pivot in a tapered hole (the first example) would be supported by a very small contact area at the small end of the bushing and that avoiding metal to metal contact would be difficult to impossible under such conditions.

One cannot really tell from the 2nd. picture whether the end of the pivot is "suspended by lubrication" or just centered in the hole by other means. If your explanation for what we see is correct, the next logical step would be to disassemble the plates and flush all the oil away with solvent and reassemble just as before. If the pivot was actually supported by lubrication before, as you suggest, then we should now see metal to metal contact similar to the first photo. If the pivot is truly suspended by lubrication, then there should also be a very high electrical resistance between the pivot and the bushing.

I rather suspect that for a pivot at rest in either a tapered hole or a hole with parallel sides, especially while under load, that the pivot would displace all or most of the oil at at the point of contact and metal to metal contact would likely be unavoidable. I would expect the thickness of any oil film remaining between these parts would be far too thin to see at this level of magnification. But repeating the demonstration with all oil removed would be informative. Not withstanding the above, it should be self-evident that a perfectly aligned straight pivot in a parallel-sided pivot will be better supported than the same pivot in a tapered hole, at least initially.
'
RC

RC
There were many more photo`s showing with and without lubrication, but they are not mine and have not found them on short notice. All of your points were covered in the presentation, but as a one finger plucker, I did not get into detail. Without Lubrication of course you could see metal to metal contact, with lubrication, only the original straight hole suspended the pivot and was without metal to metal contact. I am a firm believer in demonstrations to cover the concerns of all. Again, this was many years ago and may be worth doing again since I have not seen similar since.
My next shaky commitment depending on the virus, is the "Lone Star regional" if its held. Its in the Dallas area. At any rate, I have not finalized a program yet.

In regard to your points in post #25, there was a stark difference noticed by the audience when bushing was performed for the experiment.

The commonly suggested taper broaching procedure was utilized basically per your discussion. The taper broaching required skill as well as time consuming trial and error fitting to get the desired result. Especially since I did not have the time to do it over under the circumstances.

When I reamed the straight sided hole parallel to the arbor/pivot, I simply selected a reamer of original hole size and line bored it, per common metal working practice requiring only a few seconds per attached photo. This also required no particular skill or experience assuring desired outcome.

Jerry Kieffer

 

[D.th.munroe]

So how did you come to the conclusion from that, that a hole broached from each side by a skilled hand, not someone trying to prove against it, increases friction?
Did you measure force after the wheel before and after?
Did you use indicator on the pivots and run it dry to actually see which surfaces are actually contacting? Laser measure holes and uprightness?
You keep saying how you believe in demonstrations to prove this to all, absolutely all bases were covered and that they have undoubtedly proved your theory but when it comes to showing it here, the actual useful information comes up short.

 

[Bohemian Bill]

RC
There were many more photo`s showing with and without lubrication, but they are not mine and have not found them on short notice. All of your points were covered in the presentation, but as a one finger plucker, I did not get into detail. Without Lubrication of course you could see metal to metal contact, with lubrication, only the original straight hole suspended the pivot and was without metal to metal contact. I am a firm believer in demonstrations to cover the concerns of all. Again, this was many years ago and may be worth doing again since I have not seen similar since.
My next shaky commitment depending on the virus, is the "Lone Star regional" if its held. Its in the Dallas area. At any rate, I have not finalized a program yet.

In regard to your points in post #25, there was a stark difference noticed by the audience when bushing was performed for the experiment.

The commonly suggested taper broaching procedure was utilized basically per your discussion. The taper broaching required skill as well as time consuming trial and error fitting to get the desired result. Especially since I did not have the time to do it over under the circumstances.

When I reamed the straight sided hole parallel to the arbor/pivot, I simply selected a reamer of original hole size and line bored it, per common metal working practice requiring only a few seconds per attached photo. This also required no particular skill or experience assuring desired outcome.

Jerry Kieffer

View attachment 628829

Hi Jerry..I been watching and reading for some time here on the Clock repair forum. I like all the new method/s that you and others bring here. Great stuff. I have one question. I have been using the 5 degree tilt on pivot to bushing freedom clearances when hand reaming bushings. Do you use some ratio to pivot sizes or so many thousands of inch clearance for over-sizing your gauge pin set reamers to get proper factory clearance or do you have a chart to pick the proper gauge pin. I am thinking about purchasing and grinding a gauge pin set. I hope to meet & see you again at the Lone Star Regional. ...Bill

 

[Jerry Kieffer]

So how did you come to the conclusion from that, that a hole broached from each side by a skilled hand, not someone trying to prove against it, increases friction?
Did you measure force after the wheel before and after?
Did you use indicator on the pivots and run it dry to actually see which surfaces are actually contacting? Laser measure holes and uprightness?
You keep saying how you believe in demonstrations to prove this to all, absolutely all bases were covered and that they have undoubtedly proved your theory but when it comes to showing it here, the actual useful information comes up short.

What I had publicly demonstrated in the referenced demonstration, was that a typical movement that comes from a manufacturer or maker utilizing straight round holes as pivot holes, will have pivots that run on a oil film in some cases.

What I have never been able to accomplish nor have I ever seen anyone demonstrate , is a pivot running on a oil film in a hole sized and shaped with a tapered broach. If you can demonstrate this, then I will have to re-evaluate what I have commentated on. Since Horological pivot holes are slightly larger than the pivot, this is easily verified by the difference between lubricated and unlubricated under optics.

Even if only one pivot were to run on a oil film, the system would have less resistance than if all ran metal to metal. While very slight with only one, it would still be less.

Jerry Kieffer

 

[Jerry Kieffer]

Hi Jerry..I been watching and reading for some time here on the Clock repair forum. I like all the new method/s that you and others bring here. Great stuff. I have one question. I have been using the 5 degree tilt on pivot to bushing freedom clearances when hand reaming bushings. Do you use some ratio to pivot sizes or so many thousands of inch clearance for over-sizing your gauge pin set reamers to get proper factory clearance or do you have a chart to pick the proper gauge pin. I am thinking about purchasing and grinding a gauge pin set. I hope to meet & see you again at the Lone Star Regional. ...Bill

Bill
I do not use the 5 degree method when using gage pins as reamers.

The gage pin is used to measure the existing pivot hole and duplicate it per attached photo. The original pivot hole will be slightly larger and the correct original size pin will lock into the hole. If the pivot is reduced in size, the pivot hole is reduced by the same percentage.

If the Lone star regional is held and I get my shot in time, this very subject may be demonstrated.

Jerry Kieffer

 

[D.th.munroe]

Again I refer to my questions.

In Horology there seems to be two ways of doing things. Those that are often done by Makers and manufacturers, and the methods often suggested by repair publications, education and individuals.

This actually says alot about your opinions of how makers did things. And you are correct it is pointless to argue horological knowledge and methods with you or around you.

 

[Jerry Kieffer]

Again I refer to my questions.


This actually says alot about your opinions of how makers did things. And you are correct it is pointless to argue horological knowledge and methods with you or around you.

Sorry you feel that way.

From my perspective, I share work experiences and demonstrations as payment for those who were before me, who were so kind and generous to share theirs with myself. As in life, not everyone agreed with them either.

As mentioned many times over the years, work experiences are offered as options for everyone to evaluate. If something is of value you are welcome, if not, hopefully suggestions of others will be more useful.

Happy Holidays to one and all

Jerry Kieffer

 

[D.th.munroe]

To be honest Jerry alot of your ideas are great and helpful to many on here, you came on a little late for me.
But you do seem to assume that you are more informed about horology than anyone who comes on here and your methods are "the correct way".

When someone, formally educated in the subject, people who were in the business for years, and people who learned from apprenticeships and learned from some of those better makers, do suggest methods and knowledge that they had learned, you feel the need to come in and correct and invalidate them.
Which makes some people not want to bother trying to pass what they learned on to others.

 

[shutterbug]

I believe machinery is inherently more accurate than humans, and that has been Jerry's contention in all of his posts and demonstrations. He is a respected machinist in many different fields. Granted, he probably possesses machines that most of us would envy, but has also included ideas that those without the best tools can incorporate into their processes. He has never appeared to me to be egotistical about his opinions, but he does try to stress the difference between human interaction and machinery interaction in the horological field. Everyone has the option of either ignoring him or trying to incorporate his methods. We all have opinions and experience to share, and everyone is more than welcome to express their opinions and share their experiences here. That's what makes this forum so great!

 

[Bohemian Bill]

Sorry you feel that way.

From my perspective, I share work experiences and demonstrations as payment for those who were before me, who were so kind and generous to share theirs with myself. As in life, not everyone agreed with them either.

As mentioned many times over the years, work experiences are offered as options for everyone to evaluate. If something is of value you are welcome, if not, hopefully suggestions of others will be more useful.

Happy Holidays to one and all

Jerry Kieffer

Hi All..As I get older the term "old dogs don't want to learn new tricks" seem to be hold true more than ever. Everybody has their opinions, we all been trained by the past clockmakers/clockrepairiers/hobbiest but I am always open and appreciate to new ideas and methods if I can afford them. Clock and watch repair is my hobby. When I got started nobody locally would spend any time to share, to train, no tips or trade secrets. I assume they are thinking they would be training their competition. It was their secret and many took it to their grave. Their past experience lost forever. I wonder if many to most of the American and European clock and watch factories even wrote anything down during the years of production such as engineering drawing and specification such as pivot sizes, hole sizes and clearances and tolerances. Over twenty plus years ago, I found out about Chapter 124 clock classes in Dallas area (100 miles travel) and I took all their classes and I even later gave back as an instructor for many years. Almost all of the instructors are retired from other non horological jobs are hobbiest. I wonder why people in the clock and watch business don't want to give back for the next generation. I hope they would be open to share their knowledge gained over the years. Those who do are gems in my book.

 

[R. Croswell]

I have been using the 5 degree tilt on pivot to bushing freedom clearances when hand reaming bushings. Do you use some ratio to pivot sizes or so many thousands of inch clearance for over-sizing your gauge pin set reamers to get proper factory clearance or do you have a chart to pick the proper gauge pin.

Bill, Now that Jerry has answered your question I'll add a couple comments. I do not use the "5 degree tilt" rule for several reasons. Obviously, a pivot with the same clearance in the pivot hole will "tilt" more degrees in a thin plate or where there is a deep oil sink We are discussing (or arguing about) tapered pivot holes. Assume for the moment that the pivot hole is reamed with a tapered broach equally from both ends. The pivot can have near zero clearance at the high spot in the center of the bushing but still tilt the number of degrees corresponding to the taper of the broach, plus, as Jerry has often pointed out, a hand-held tapered broach will always ream a greater angle than the actual angle of the broach being used. In both of these examples the angle of tilt is not a true indication of the actual clearance between the pivot and the pivot hole.

If the pivot hole has true parallel sides and the openings are not chamfered, then a bit of math can provide the actual clearance of the pivot in the hole given the thickness of the plate and angle of tilt. But we usually do chamfer the openings and it isn't easy to accurately measure the degrees of tilt with any serious precision. And just what clearance is correct for any given position in going train of any particular movement? So what is one to do?

Jerry has provided one method when dealing with straight pivots in straight pivot holes where the size of the original pivot hole and pivot are known or can be determined. That pretty much "goes out the window" when one is using tapered broaches, which I suspect the majority of people repairing clocks probably do use. So here's my own rule that everyone is free to disagree with or not but it works for me in most cases. Keep in mind that if the pivot fits too tight the clock will have running issues and if it fits just a bit loose it will likely run OK but part of the life of the bushing that would otherwise be reserved for future wear has been lost to excessive reaming / broaching. With the pivot in the hole, I place the opposite plate in position over the opposite pivot but not allowing the pivot to enter the hole. Check the tile for 360 degrees and note its position relative to the pivot hole in the opposite plate. Look for two things - 1) the pivot should generally tilt at least one pivot diameter from the edge of the hole, and 2) the pivot should tilt the same amount from the hole over all 360 degrees. This establishes that there will be some running clearance, and that the reamed / broached hole is perpendicular to the plate. This is a qualitative test - go no go test, not a quantitative test to verify a specific mm clearance.

RC

 

[Bohemian Bill]

Bill, Now that Jerry has answered your question I'll add a couple comments. I do not use the "5 degree tilt" rule for several reasons. Obviously, a pivot with the same clearance in the pivot hole will "tilt" more degrees in a thin plate or where there is a deep oil sink We are discussing (or arguing about) tapered pivot holes. Assume for the moment that the pivot hole is reamed with a tapered broach equally from both ends. The pivot can have near zero clearance at the high spot in the center of the bushing but still tilt the number of degrees corresponding to the taper of the broach, plus, as Jerry has often pointed out, a hand-held tapered broach will always ream a greater angle than the actual angle of the broach being used. In both of these examples the angle of tilt is not a true indication of the actual clearance between the pivot and the pivot hole.

If the pivot hole has true parallel sides and the openings are not chamfered, then a bit of math can provide the actual clearance of the pivot in the hole given the thickness of the plate and angle of tilt. But we usually do chamfer the openings and it isn't easy to accurately measure the degrees of tilt with any serious precision. And just what clearance is correct for any given position in going train of any particular movement? So what is one to do?

Jerry has provided one method when dealing with straight pivots in straight pivot holes where the size of the original pivot hole and pivot are known or can be determined. That pretty much "goes out the window" when one is using tapered broaches, which I suspect the majority of people repairing clocks probably do use. So here's my own rule that everyone is free to disagree with or not but it works for me in most cases. Keep in mind that if the pivot fits too tight the clock will have running issues and if it fits just a bit loose it will likely run OK but part of the life of the bushing that would otherwise be reserved for future wear has been lost to excessive reaming / broaching. With the pivot in the hole, I place the opposite plate in position over the opposite pivot but not allowing the pivot to enter the hole. Check the tile for 360 degrees and note its position relative to the pivot hole in the opposite plate. Look for two things - 1) the pivot should generally tilt at least one pivot diameter from the edge of the hole, and 2) the pivot should tilt the same amount from the hole over all 360 degrees. This establishes that there will be some running clearance, and that the reamed / broached hole is perpendicular to the plate. This is a qualitative test - go no go test, not a quantitative test to verify a specific mm clearance.

RC

Hi RC..I just back from "Bill's meals on wheels" ..I cooked and took some Christmas meals to my disabled brother and also long time friend. .Your method make a lot of sense and is logical. I have been using the 5 or more degree but is it really 5 degree?. I don't measure it but looks okay but how to you teach it to new green students. I was teaching/showing a kitchen clock repair last week to my replacement engineer since I am retiring shortly (he was interested in my hobby) but visually he could not visually know what was 5 degree tilt. I got a protractor and cut a 5 degree wedge for reference. RC you are right that oil sink holes do make a difference in thickness thus make a difference in pivot clearance.
RC what Jerry's method using the ground gauge pin would work if both pivots was good in original shape, right location and same size but will not work in all cases if one side pivot diameter in the past was reduced due to worn grooves and the other was not. Also many to most of these 100 year plus old movements may not have the original hole for reference size. In my opinion, I would like to see a pivot diameter chart or formula with suggested reamer sizes so a person can choose proper reamer and place it in your KWM or Bergeon bushing machine and ream the bushing hole to size right after bushing installation and the pivot hole will be straight and parallel and the right size for the given pivot size. Just a thought.

 

[howtorepairpendulumclocks]

Couple of things to chip in here.... by the way I'm really enjoying the exchange of info. Firstly, I thing the five degrees is a good rule of thumb. If the clock frame is rigid like a regulator, you can get away with much less as long as the mobile is uprighted i.e. perpendicular to the plate. That is of course that the other hole is exactly lined-up at the other side of the frame! Certainly not always the case. Ultimately, what is important here is depthing i.e. depth of mesh of mating mobiles.... The other thing is I had a couple of hours to spare so I did an admittedly very non-scientific experiment. I wanted to see for myself what the "broached from both sides" holes looked like so I made one and cut it open. To compare, I also made a similar hole with a new modern twist drill (Tin dormer) and I made an "old-fashioned" spade drill for fun. As I say this is totally non-scientific so make of it what you will. I used 5mm diameter Bergeon bushing wire which is already drawn to approx. 1.75mm bore. I drilled/broached to approx. 2mm diameter. As can be seen, the broached hole is far smoother than either of the drilled versions. Not a surprise. I have no way of testing the hardness of the wall but imagine the very negative "top rake" of the broach has a work-hardening effect as well as a cutting/scraping one. Anyway, make what you will of the attached images. The sample with one notch in the outer wall is broached, 2 notches, spade drill, three notches, modern twist drill. PS the second 'bush' on the broach was my depth stop so I could broach from both sides by roughly the same amount. wishing you all a very Happy Christmas. HTRPC

 

[howtorepairpendulumclocks]

... I should add that a smooth bearing surface is not necessarily a "good" bearing surface. Look at a hand-scraped machine tool bed for example... )

 

[D.th.munroe]

I never said hand work was more accurate than machines and I never said Jerry wasn't respected or that he is incorrect, although by the majority of his posts it appears he believes he is the only authority, all education and individuals are incompetent and incorrect. Jerry's contention appears to be more that handwork has no place in horology, and a waste of time learning those skills. Apparently you can't teach old dogs old tricks either or to describe to them "lost secrets of past masters, they won't believe you and tell you that "competent people do it their way" when really you were trying to help someone else aquire skills with methods you haven't used in years.
I really recommend beginners to listen to R. Croswell

 

[Bohemian Bill]

Couple of things to chip in here.... by the way I'm really enjoying the exchange of info. Firstly, I thing the five degrees is a good rule of thumb. If the clock frame is rigid like a regulator, you can get away with much less as long as the mobile is uprighted i.e. perpendicular to the plate. That is of course that the other hole is exactly lined-up at the other side of the frame! Certainly not always the case. Ultimately, what is important here is depthing i.e. depth of mesh of mating mobiles.... The other thing is I had a couple of hours to spare so I did an admittedly very non-scientific experiment. I wanted to see for myself what the "broached from both sides" holes looked like so I made one and cut it open. To compare, I also made a similar hole with a new modern twist drill (Tin dormer) and I made an "old-fashioned" spade drill for fun. As I say this is totally non-scientific so make of it what you will. I used 5mm diameter Bergeon bushing wire which is already drawn to approx. 1.75mm bore. I drilled/broached to approx. 2mm diameter. As can be seen, the broached hole is far smoother than either of the drilled versions. Not a surprise. I have no way of testing the hardness of the wall but imagine the very negative "top rake" of the broach has a work-hardening effect as well as a cutting/scraping one. Anyway, make what you will of the attached images. The sample with one notch in the outer wall is broached, 2 notches, spade drill, three notches, modern twist drill. PS the second 'bush' on the broach was my depth stop so I could broach from both sides by roughly the same amount. wishing you all a very Happy Christmas. HTRPC

View attachment 628921 View attachment 628922 View attachment 628923 View attachment 628924 View attachment 628925 View attachment 628926 View attachment 628927 View attachment 628928

Hi All..Great Great forum debate ....Thanks Howtorepair for excellent experimentation you did, could you add Jerry's method in post 29 by taking a 2mm steel ground 12 degree cutting edge and compare it to other three bushing cutaways?

 

[howtorepairpendulumclocks]

Yup, I’ll do that tomorrow.

 

[TooManyClocks]

I never said hand work was more accurate than machines and I never said Jerry wasn't respected or that he is incorrect, although by the majority of his posts it appears he believes he is the only authority, all education and individuals are incompetent and incorrect. Jerry's contention appears to be more that handwork has no place in horology, and a waste of time learning those skills. Apparently you can't teach old dogs old tricks either or to describe to them "lost secrets of past masters, they won't believe you and tell you that "competent people do it their way" when really you were trying to help someone else aquire skills with methods you haven't used in years.
I really recommend beginners to listen to R. Croswell

I listen to both Jerry and RC. They both have my respect and I have learned from each of them. Jerry is way above my skill level, but I take what I can learn and adapt it with the tooling and mediocre skill I possess, trying to improve. Jerry has taken time to help with little stuff that is at my level, and I have improved as a result. Same with RC and many others here. If as is most of the time, his methods and tooling are beyond me, fine, someone else will pick something up and learn from him.

Helping out—freely given should never be discouunted or discouraged. Opinions come with the teaching and the teacher should have an opinion. What is done with the information and opinions that come with it and how they are absorbed is up to the individual, hopefully in a positive manner. Otherwise, ignoring the thread entirely or the individual’s response that becomes frustrating may be the best idea. History on this message board has shown that some individuals have been run off or others just get mad and never come back when differences become heated. It can be a slippery slope.

No one asked my opinion on any of this. I’m just concerned about the direction it seems to be taking.

John

 

[Thomas Sanguigni]

I think it is best to absorb what others teach to us. Take away from it what you can. Adapt your skills and shop as you can. We can not do anything but our best. I have added lots of skills since I started, and have stopped using others. Turn out the best work you can.

 

[D.th.munroe]

Really my point was that someone who's skills are above that of Jerry's and see his work for what it is, just basic machining techniques, get discredited by his comments and his sometimes incorrect assumptions on how things were done by makers and manufacturers, and how things should be done, beginners and people that don't know are dazzled by his confidence in his knowledge on doing and demonstrating these techniques and see him as a guru, but with that comes the responsibility of helping people who don't have the tools you have, helping them with what they have. Not discouraging them by saying it can only properly or remotely successfully be done one way.

The secrets of the past masters was, there is very few secrets, it was years of skill acquisition with the same tools many still use, practice and intuition, knowing what the outcome had to be and using what you had and the best of your abilities to come to that outcome.

 

[Jerry Kieffer]

Hi RC..I just back from "Bill's meals on wheels" ..I cooked and took some Christmas meals to my disabled brother and also long time friend. .Your method make a lot of sense and is logical. I have been using the 5 or more degree but is it really 5 degree?. I don't measure it but looks okay but how to you teach it to new green students. I was teaching/showing a kitchen clock repair last week to my replacement engineer since I am retiring shortly (he was interested in my hobby) but visually he could not visually know what was 5 degree tilt. I got a protractor and cut a 5 degree wedge for reference. RC you are right that oil sink holes do make a difference in thickness thus make a difference in pivot clearance.
RC what Jerry's method using the ground gauge pin would work if both pivots was good in original shape, right location and same size but will not work in all cases if one side pivot diameter in the past was reduced due to worn grooves and the other was not. Also many to most of these 100 year plus old movements may not have the original hole for reference size. In my opinion, I would like to see a pivot diameter chart or formula with suggested reamer sizes so a person can choose proper reamer and place it in your KWM or Bergeon bushing machine and ream the bushing hole to size right after bushing installation and the pivot hole will be straight and parallel and the right size for the given pivot size. Just a thought.

Bill
It is unlikely anyone one system will work in all cases every time. All you can do is find something that works 99 percent of the time and have a backup option.
In using gage pins, you will need to first find one that locks on to the original pivot hole and note the diameter. That pin in turn can be used to position a mill spindle in the location of the original pivot hole for using a bushing reamer. Next you would measure a unworn section of the pivot and note its diameter. In doing this you start to note relationships between the two noted figures and soon realize that typical factory pivots are about 4-5 percent smaller than factory pivot holes.

Any pivot that is dressed to a reduced size, reduce the pivot hole by the same percentage.

So lets assume you run into the rare occasion when the opposite pivot hole is two small or the hole to be bushed has been modified beyond original. Since you now have an idea of typical pivots and pivot hole relationships, you can reverse engineer. Simply measure a dressed pivot and increase the measurement by 4-5 percent for the pivot hole. On the rare occasion the rear pivot hole is again to small ream from the front unsupported.
After reaming, push the reamer all way back centered to the rear pivot hole to check reamed alignment fit.

Jerry Kieffer

 

[bruce linde]

. 2) the pivot should tilt the same amount from the hole over all 360 degrees. RC

quick way to determine if a pivot hole is out of round, and where the most wear is.