• Important Executive Director Announcement from the NAWCC

    The NAWCC Board of Directors is pleased to announce that Mr. Rory McEvoy has been named Executive Director of the NAWCC. Rory is an internationally renowned horological scholar and comes to the NAWCC with strong credentials that solidly align with our education, fundraising, and membership growth objectives. He has a postgraduate degree in the conservation and restoration of antique clocks from West Dean College, and throughout his career, he has had the opportunity to handle some of the world’s most important horological artifacts, including longitude timekeepers by Harrison, Kendall, and Mudge.

    Rory formerly worked as Curator of Horology at the Royal Observatory, Greenwich, where his role included day-to-day management of research and digitization projects, writing, public speaking, conservation, convening conferences, exhibition work, and development of acquisition/disposal and collection care policies. In addition, he has worked as a horological specialist at Bonhams in London, where he cataloged and handled many rare timepieces and built important relationships with collectors, buyers, and sellers. Most recently, Rory has used his talents to share his love of horology at the university level by teaching horological theory, history, and the practical repair and making of clocks and watches at Birmingham City University.

    Rory is a British citizen and currently resides in the UK. Pre-COVID-19, Rory and his wife, Kaai, visited HQ in Columbia, Pennsylvania, where they met with staff, spent time in the Museum and Library & Research Center, and toured the area. Rory and Kaai will be relocating to the area as soon as the immigration challenges and travel restrictions due to COVID-19 permit.

    Some of you may already be familiar with Rory as he is also a well-known author and lecturer. His recent publications include the book Harrison Decoded: Towards a Perfect Pendulum Clock, which he edited with Jonathan Betts, and the article “George Graham and the Orrery” in the journal Nuncius.

    Until Rory’s relocation to the United States is complete, he will be working closely with an on-boarding team assembled by the NAWCC Board of Directors to introduce him to the opportunities and challenges before us and to ensure a smooth transition. Rory will be participating in strategic and financial planning immediately, which will allow him to hit the ground running when he arrives in Columbia

    You can read more about Rory McEvoy and this exciting announcement in the upcoming March/April issue of the Watch & Clock Bulletin.

    Please join the entire Board and staff in welcoming Rory to the NAWCC community.

Smooth Broaching New Bushings

D.th.munroe

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And this will be my last post.
Merry Christmas Everyone!
 

howtorepairpendulumclocks

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...as above, just done a 2mm D reamer. As kind of expected, the hole appears quite smooth, the tool has zero top-rake but also scored which I presume is swarf stuck in the hole. I did it a couple of times with similar looking results. Anyway. Totally non-scientific but something I've been wanting to get round to for years. Hope it helps the exchange and of course, Happy Christmas :=)

IMG_1504.JPG IMG_9609.JPG IMG_9630.JPG IMG_9641.JPG
 
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Bohemian Bill

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Merry Christmas Howtorepair...You must got up early. this Christmas morning ..Did you find your present/s under the tree already?..
Just what I thought but I believe Jerry's gauge pin reamers were only a 12 degree angle flat ground from the axis of the rod only from one side.. not a D reamer ..I have been going researching through couple dozens of my old clock repair books yesterday and could not find of any mention of measurable clearance/s between the clock pivot and bushing. I seen several mentions of the 5 degree tilt. The Conover's Clock Repair Basic book on page 33 state "that an unworn hole is round. In most cases the hole is .002 " larger in diameter than the pivot, but in some clocks the difference in diameters will be more or less than that." Thanks
 

howtorepairpendulumclocks

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Yes, It is all fascinating. Like all rules of thumb, the five degree thing is just a place to get folks started I suggest. Very broadly, the more rigid the frame, the tighter the tolerances can be? That is good and why I'm here I hope to encourage :=) I'm not quite sure what Jerry's reamer is but presume it is something similar, hardened steel with single cutting face/plane? Anyway, hope my little experiment helps. I can totally see that where you have a mobile that isn't uprighted, the method of running the reamer through both holes is really useful. The broach method of finishing the hole gives "infinite" flexibility for the repairer. It also seems to result in the smoothest hole and is likely to be the most work-hardened too. Either way, I love this exchange of info, the more techniques in the 'armoury', the better. In this conversation, I'd like to see more emphasis on depthing before launching into bushing (intervention). Anyway, that's for another day...
 

R. Croswell

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And this will be my last post.
Merry Christmas Everyone!
I truly hope not! While a few of your comment are a little close to the edge of what's allowed, the points of fact you make are important. Many of us I'm sure share some of your concerns. No one is right all the time or so great that what they say should never be questioned - no one. Hopefully we can all share here the ways we would do a specific repair and why without insisting that everyone should do it "my way" or your work is inferior.

We do have a few interesting characters that participate here, and when I see their names come up I already know what they are going to say before I read it. One fellow is going to say that everything is worn out and every pivot hole needs to be bushed, another is OK with any half-fast method that will make the clock at least sort of run, one insists that all repairs be invisible, and so on. and occasionally one just gets mad and leaves which is everyone's loss.

Hope everyone has a safe Christmas.

RC
 

shutterbug

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I've been toying with the idea of making a pin vise of sorts that will fit centered in my bushing machine. I would like to have a mill, but clicked over another year yesterday, and a mill is not in my future. Anyway, the make-shift pin vise would give me the ability to use gauge pins instead of broaches, and give me a more accurate method of enlarging the center hole of bushings I install. What do you think?
 

Bohemian Bill

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I've been toying with the idea of making a pin vise of sorts that will fit centered in my bushing machine. I would like to have a mill, but clicked over another year yesterday, and a mill is not in my future. Anyway, the make-shift pin vise would give me the ability to use gauge pins instead of broaches, and give me a more accurate method of enlarging the center hole of bushings I install. What do you think?
Merry Christmas shutterbug...I have an old pin vise that hold 8mm lathe collets. I am looking and wishing for a gauge pin set on the website that will work with my old pin vice that I will soon possibly adapt in my Bergeon bushing machine. Just a thought..Bill
 

R. Croswell

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I've been toying with the idea of making a pin vise of sorts that will fit centered in my bushing machine. I would like to have a mill, but clicked over another year yesterday, and a mill is not in my future. Anyway, the make-shift pin vise would give me the ability to use gauge pins instead of broaches, and give me a more accurate method of enlarging the center hole of bushings I install. What do you think?
I got a tiny "drill chuck" which was basically a pin vice from timesavers and turned down the shank to fit the Bergeon machine. I think the idea was good but the dang thing was made in India and not very true. I believe it would work if you start with a decent pin vice.

RC
 
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shutterbug

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I'm going to give it a try. My shop isn't completely done yet, so will take some time.
 

Kevin W.

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Whats the purpose of holding with a pin vice or a small chuck?
 

Jerry Kieffer

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Yes, It is all fascinating. Like all rules of thumb, the five degree thing is just a place to get folks started I suggest. Very broadly, the more rigid the frame, the tighter the tolerances can be? That is good and why I'm here I hope to encourage :=) I'm not quite sure what Jerry's reamer is but presume it is something similar, hardened steel with single cutting face/plane? Anyway, hope my little experiment helps. I can totally see that where you have a mobile that isn't uprighted, the method of running the reamer through both holes is really useful. The broach method of finishing the hole gives "infinite" flexibility for the repairer. It also seems to result in the smoothest hole and is likely to be the most work-hardened too. Either way, I love this exchange of info, the more techniques in the 'armoury', the better. In this conversation, I'd like to see more emphasis on depthing before launching into bushing (intervention). Anyway, that's for another day...
The reamer was constructed using a gage pin that are hardened and ground and ground per attached photo.

Jerry Kieffer

fullsizeoutput_7a2.jpeg
 

woodlawndon

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Man, you guys are good tool grinders, I'd love to see your process to get that kind of precision. I don't think my present skill level could get that close.

I was intrigued by Jerry's 4-5% pivot hole comment, hadn't heard that measurement before. If you have say a common 1.20 mm pivot, 4% is pretty close to 1.25 mm. When I have to bush for a 1.2 mm pivot I will use a 1.25 mm bushing or if I don't have one I will use a 1.2 and broach to size. This all seems to be very close and if you use the 5% tilt method to verify it also comes very close. Just found this interesting.
Don
 
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bikerclockguy

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

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....
Bruce, you summed it up nicely and hit the nail on the head. I too use the ”spin test“ between the plates as my final determination on whether the ID is ok as is or needs a little work.
 

bruce linde

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i also then check it against the previous gear in the train and make sure they do that easy spin thing together... and then move on up the train. i've learned that if i don't do that, i'll end up coming back to do it because i should have done it the first time. :)
 

David Provan

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I've always assumed that the main reason for horologists using tapered reamers and broaches was to allow a very wide range of holes to be sized without needing an equally large number of drills and reamers. As a larger scale engineer (yes, I am dieting) I'm used to parallel sided bearings and pinions.

But I'm going to follow this thread with interest.

Regards, David
 

Ralph B

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Interesting old video here from Elgin, who probably knew a thing or two in their day.
It's about how chronometer jewels were made, and if you fast forward to 58.30 they explain why, when the jewels have been made, they have a taper put into them from each side.
They are jewels, rather than brass, but I thought it might have some "bearing" on the topic under discussion, ( ho, ho, sorry....).
And bear in mind, ( still at it...), that chronometers have plates that are aligned considerably better than pretty much any clock you can think of.

 
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Bohemian Bill

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I've been toying with the idea of making a pin vise of sorts that will fit centered in my bushing machine. I would like to have a mill, but clicked over another year yesterday, and a mill is not in my future. Anyway, the make-shift pin vise would give me the ability to use gauge pins instead of broaches, and give me a more accurate method of enlarging the center hole of bushings I install. What do you think?
Hi Shutterburg..I just thought of it..Dremel has a small adjustable drill chuck that might be the answer if you can adapt it and be a better quality chuck..Just a thought. I seen them at Home depot and Lowes in the tool section with all the Dremel accessories
 
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shutterbug

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Thanks, Bill. i have a Dremel drill press, and never thought of it. Good idea!
 

shutterbug

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Whats the purpose of holding with a pin vice or a small chuck?
The goal is to keep the pin absolutely vertical, so the hole is straight with the plate. The jaws have to adjust to any size pin, but must also center it.
 
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R. Croswell

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The goal is to keep the pin absolutely vertical, so the hole is straight with the plate. The jaws have to adjust to any size pin, but must also center it.
The problem I ran into is that there is limited space between the Bergeon upper arm and the work piece. Here is the small made in India chuck that I fitted to the Bergeon machine and the Dremel chuck. If you can match the fine thread Dremel shaft I think it could work. The chuck screws onto the shaft to close the jaws. The Dremel shaft is hollow. I find the Dremel chuck to run surprisingly true. I've hand-held the tool with carbide PC board drills. A little wobble in the Bergeon quill should not be a problem for just holding a broach on true vertical. (The drill and scrap plate are just for illustration. The hole was already in the plate)

RC

chuck-1.jpg chuck-2.jpg chuck-3.jpg
 
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Kevin W.

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Thanks Robert for the pictures and explanation. I have a jacobs chuck that came with my Bergeron bushing machine. Never used it though.
 

Jerry Kieffer

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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.
While I do not want to prolong this thread, I have been busy the last couple of days and missed this posting for some reason and would like to respond for clarification.
First I would like to commend Mr. Munreo (If thats correct) for being a Donor that I assume is to the message board.

Personally, I spend many hundreds of hours helping beginners mostly on my own time, in what I see as payback as mentioned. One example of this is that I have constructed/machined a 16s 19 jewel 100 percent bar stock watch movement (Minus jewels and hairspring) on my own time and expense that is utilized in the class room for beginners to evaluate. It was purposely constructed as a very basic movement utilizing construction procedures that beginners can master on their first or second attempt to rapidly build confidence. Those attending classes recently have had a chance to evaluate this movement. To accompany this, a large 12" diameter demonstration version was also constructed that highlights escapement function per the attached poor quality photo before completion. (only photo I could find)

Mr. Munroe is absolutely correct that all of my suggestions and demonstrations are basic machining practices where machining is involved. It is purposely done this way since it is the foundation of skill development and allows beginners the ability to easily master what is presented.

Regarding hand work, it is ironic that all of my suggestions in this thread have been handwork procedures. However, I do often take a different approach that can offend some even if mentioned as an option. I have talked to others who have also experienced this, thus I am never offended. Personally I believe that machine work is best duplicated and repaired utilizing machine work, and hand work duplicated and repaired by handwork. It is a practice that I follow. Unfortunately, todays labor rates where its a concern, can greatly effect what is practical to accomplish with hand work. My personal solution is to rapidly remove 80-90 percent of the metal requiring removal with machine tools. At this point, most of my time is then spent hardworking and aging surface finishes to duplicate the originals. This includes duplicating all inconsistencies of the originals.
An example requiring unusual handwork detail is as follows, I was asked to restore part from a very valuable tower movement that was missing a section. I was also asked to save the small casting flaw second photo arrow. Third photo arrow shows the end result.

However, this thread is also a good example of two different approaches as follows.

Mr. Munroe offered his method of broaching a hole utilizing his skilled hands that is a trial and error method, if I understood correctly.

In post #29 I covered the method that I typically use. It initially was a light bulb moment that came about many years ago when working with a beginning repair person and is a refined version of what was used before. It offers a predetermined method of returning a pivot hole back to original state, requiring little to no skill that a beginner can easily master on their first attempt.

Looking back at myself when I started, I was as dumb as a sack of rocks. I was often told that there was only one way of doing things and that was the way it was done in the past. When I asked why, they often became unhinged. The few that were very confident and did not take that approach, were my mentors and life savers. Someone on this list mentioned to me at one time "All of the old masters used the latest tools and procedures available to them at the time" I have found it interesting and true.

Today, my goal is to help those in the same boat I was in.

Right or wrong, sometimes you are compelled to respond.

Jerry Kieffer

DSCN1683.jpg fullsizeoutput_5bf.jpeg fullsizeoutput_70b.jpeg
 
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shutterbug

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T!hanks for those pic's, RC. Jerry, what do you think of that idea? I'm considering gauge pins instead of drill bits.
 

Jerry Kieffer

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T!hanks for those pic's, RC. Jerry, what do you think of that idea? I'm considering gauge pins instead of drill bits.
Shutterbug
I am always truly amazed at the longevity of 100 year old inexpensive movements that are being bushed for the first time. Thus my expressed passion to return to original state.

However, when returning one thing to its original state such as a pivot hole by drilling or reaming 90 degrees to the plate, its important to return the rest of the movement to the same state for original function. Two of the things that I see the most important when repairing a movement, is to check each movement pillar to make sure it is square with the plate and make sure that all movement mounting points make equal contact to the mounting surface. An aligned unstressed movement now has its greatest chance to function as original.

When I first started using the Milling machine for bushing, I also reamed the hole using the Mill without any issues. I no longer do it because of my preferred routine of doing things, but thats just my thing.

I see no issue doing it with a bushing machine provided that the whatever is used such as drill or reamer is running true without runout and aligned to the bushing hole.

I should add that using a tapered broach in this manner, greatly increases the quality of a hole broached by hand. However, its still a modification from original and remains a trial and error method.

Jerry Kieffer
 
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Kevin W.

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For many, its just a hobby, and their budget does not allow for a mill or bushing machine. But at the same time i understand thats what used needs to be kekp square to the plate while the hole is reamed or broached.
 

R. Croswell

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For many, its just a hobby, and their budget does not allow for a mill or bushing machine. But at the same time i understand thats what used needs to be kekp square to the plate while the hole is reamed or broached.
I believe the two most important considerations when bushing are that the hole in the bushing be centered over the original hole, and that the hole in the bushing (after any reaming or broaching) be perpendicular to the plate. I think too much emphasis is sometimes given to whether the hole is straight reamed or taper broached. Considering the angle of the tapered broach and the thickness of a typical movement plate, especially if the hole is taper broached an equal amount from both sides, the difference in diameter of the hole over the length of the bushing isn't going to cause any operational problems in most ordinary clocks, but an off-center or crooked bushing will. If one's objective is to duplicate precisely the original construction then tapered broaches should not be used, If the objective is a durable repair using a widely accepted method, there is no reason not to broach bushings. It isn't that one method is superior to the other so much as one method may be more appropriate for a given situation considering the outcome objective and the resources available.

RC
 
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Kevin W.

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So besides a tapered broach, what can be used by someone who has a small budget to size a hole for a pivot?
 

Old Rivers

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So besides a tapered broach, what can be used by someone who has a small budget to size a hole for a pivot?
Kevin,

Here is what I use:


As Jerry Keiffer has presented, you can grind a flat diagonally on one end of the pin (they're 2" long) and use it as a reamer. This doesn't hurt the utility of the pin for its original purpose.
I use mine all the time. I bought a second set with smaller diameters.

Bill
 
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R. Croswell

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So besides a tapered broach, what can be used by someone who has a small budget to size a hole for a pivot?
The best option of course is to select a bushing that fits without the need to ream or broach. Reamers made from gage pins can also be made from pivot wire or music wire if you are lucky enough to find the correct size. If your budget already includes a lathe and a decent selection of collets a miniature boring bar is fairly inexpensive and will allow you do true bore the opening of most of the bushings used in ordinary clocks. For "someone who has a small budget" don't let one individual's campaign against tapered broaches keep you from considering that option. If you get a good set (Swiss or German made) and select a set that has a large number of broaches to cover a given range (minimal taper), and take care to keep the broach perpendicular to the plate by using the opposite plate as a guide, then for all practical purposed the result can be quite acceptable and the clock will never know how its bushings were sized.

RC
 
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Kevin W.

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For now i will check for run out on my Bergeron bushing machine, and i dont hand broach too often. I may look into some non tapered broaches later. Thanks for your help on this mb.
 

Michael Linz

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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
Just to be clear, when you used the broach, you did it from both sides of the bushing?
 

howtorepairpendulumclocks

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It turns out drills are really rubbish things for making good round holes. drill out by all means but good old clockmakers broach to finish to size. as above, the negative cutting angle also work-hardens the hole so win win.
 
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Willie X

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I have done many test with 400 day clocks and found that round broaching definitely makes a difference in the way they ran. I'm sure the effect would be much less effect on clocks with more power but a difference would be there just the same.

IMO drills have no place in the fitting of pivots into their holes.

Willie X
 
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bikerclockguy

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Thank you. I was impressed by the difference in the smoothness of the holes. I would've thought the one made with the drill would be the smoothest. Guess not...
I think the key benefit from smooth broaching, is just that; its smoothing effect. Not to take away from striving for a precise fit and perpendicular angle, but from what I’ve observed, the reality is that a lot of that goes right out the window when the train is under load from the spring. Having smooth mating surfaces(in my opinion)compensates for a lot of that loss. The neoprene lip on an oil seal, running perpendicular to a forged steel crankshaft, will cut a groove in it after running for a few years.
 

D.th.munroe

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I hadn't planned on coming back to this thread but I do need to apologize for my reaction earlier in this thread.
I have seen Jerry's work many times before.

But there is some basic practical physics and basic past machining techniques that are fully ignored in those arguments against using broaches.
I didn't only study these old techniques for 25 years, I practiced them and tested results.
Impossible things to do are to accurately enlarge a hole a little bit with a hand made drill bit and a bow, or to drill to size a gun barrel that won't blow up in your face.

Here are some tips on using broaches from the 1700s,
Wood handles should be used that are light enough to let go of the handle and check uprightness, with a heavy handle this is harder and can ruin the hole.
The small broaches with thin handles enabling you to make at least one full rotation of the tool with your fingers, larger broach handles should also have the end of the handles thinned to do the same.
Beginners who have a hard time keeping the broach upright can be aided by a cork put in the mandrel and pierced through the center and then pushed on to the broaches keeping the flat part of the cork parallel with the plate until they are proficient. New cutting broaches should have the cutting edges rubbed a tiny bit with a stone to remove the feather edge as to not leave any pieces in the brass. Smooth broaches should be straight grained lengthwise with crocus and in all cases use plenty oil and clean often.
Dan
 

shutterbug

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I've mentioned before that the major factor in bearing surfaces is the pivot. The entire circumference of the pivot is active, but only a very small portion of the hole is. Therefore, smoothing the hole is not without some merit, but not as important as smoothing the pivot itself. Even a rough surface on the hole will smooth out pretty quickly on its own with most clocks.
The 400 day clocks run way slower and with way less power, so everything has to be right with them. Even more so on the Atmos clocks which only escape twice per minute :)
 

TEACLOCKS

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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

Thank you
Jerry Kieffer for this GREAT tool IDEA.
I never did like the idea of tapering bushings.
The factory never tapered there bushings.
I have been sharpening as needed, And I get the Clearance I want pivot to bush.
So far the pins have been long enough to reach through both plates.
Thank you Again
 
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Jerry Kieffer

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Thank you
Jerry Kieffer for this GREAT tool IDEA.
I never did like the idea of tapering bushings.
The factory never tapered there bushings.
I have been sharpening as needed, And I get the Clearance I want pivot to bush.
So far the pins have been long enough to reach through both plates.
Thank you Again
Teaclocks
You are welcome.

However I cannot take all of the credit. The procedure is accentually line boring that is a very common practice in the world of metal working.

Jerry Kieffer
 

Ralph B

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The factory never tapered there bushings.
Actually, they did.
If you look at post 67 you'll see that no less a manufacturer than Elgin did, and the reasons they did.
And they were doing it on chronometers no less, where the requirement for accuracy was far more necessary than the clocks we generally deal with.
If it was good enough for them, it's certainly good enough for me.
 

Jerry Kieffer

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Actually, they did.
If you look at post 67 you'll see that no less a manufacturer than Elgin did, and the reasons they did.
And they were doing it on chronometers no less, where the requirement for accuracy was far more necessary than the clocks we generally deal with.
If it was good enough for them, it's certainly good enough for me.
Ralph
While there will always be exceptions to everything, I do not recall ever seeing what I considered factory produced tapered holes in brass plates or bushings.

The video is dealing with jewels that are utilized quite differently because they are very hard and not susceptible to wear as easily as brass.
In this case, contact area can be greatly decreased and cap jewels are often utilized in the most critical areas that also act to retain constant lubrication in minimal contact areas such as the escapement. Under these conditions friction is greatly reduced as is the goal.

If these same conditions were applied to brass bushings, rapid wear can easily occur as can be observed under optics when taper holes are utilized to fit pivots.

Jerry Kieffer
 
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murphyfields

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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.
Bruce, you summed it up nicely and hit the nail on the head. I too use the ”spin test“ between the plates as my final determination on whether the ID is ok as is or needs a little work.
i also then check it against the previous gear in the train and make sure they do that easy spin thing together... and then move on up the train. i've learned that if i don't do that, i'll end up coming back to do it because i should have done it the first time. :)
I like the spin test idea. Simple and practical. Just to clarify, are you looking for a smooth spin even without oil, or do you make sure that piggy is really greased (well, oiled anyway) before taking him for a spin?
 

bruce linde

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I like the spin test idea. Simple and practical. Just to clarify, are you looking for a smooth spin even without oil, or do you make sure that piggy is really greased (well, oiled anyway) before taking him for a spin?

this is all before final (hopefully!) reassembly and oiling. if the pig slides without oil, imagine how much better it will be w/ oil. :)
 
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