Tight fitting bushing query??

NEW65

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I am constantly fitting bushings in worn clock plates, after all this is what we all do :)
I like to ensure that the bushings are quite tight. I use a light weight hammer with the plate sitting on an heavy duty slab of steel and tap the bushings firmly in place with the hammer. I’ve never had any problems doing this before.
Tonight was no exception - I fitted 12 bushings in the plates. However for the first time ever I noticed that 3 of the gears had no end play when I did the usual drop test. I couldn’t figure out why though as the bushings were dead flush with the insides of the plates? I thought for a moment that one of the brass plates must have been warped!
I was baffled why this has happened :???: Any thoughts??
The only thing possible was that a few bushings that had been fitted were quite tight.., could hammering in a bushing that is too tight cause the (hole ) plate to bulge? Even when sitting on a perfectly flat slab of heavy duty steel could this happen? If this is the case then it’s never happened before to me and I’ve used this method on hundreds of movements .Any thought chaps?
Thanks:)
 

Willie X

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Yes, if you are hammering the nose of the bushing against the anvil.

The bushing should be pressed in from the back of the plate with the front (nose/outside) end open. i.e. a hole in the anvil, or a hollow post, as on a bushing machine's stump.

Also, all bushings should be slightly chamfered on the inside edge of the pivot hole.

Willie X
 
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wow

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If a bushing is off center slightly the arbor will be at a slight angle causing the pivot to bind. How do you determine the center? Do you mark the direction of the wear somehow and account for that when cutting the hole? A reamer is great for cutting in one direction and rounding out the hole on center. Do you use reamers or do you broach the hole? And yes, I think driving in bushings with a hammer would spread the ID of the bushing. If the hole is cut the proper diameter, the bushing should just pop in with a small amount of pressure. You said you put 12 bushings in the plates. I don’t normally find nearly that many worn bushings. Usually about 4-6 bushings.
 
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Bruce Alexander

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Are you sure there was end-shake before your work?

You placed a fair number of bushings.

Some questions that come to mind...

Were they grouped closely in the warped area?
How much force are you using?
Is it possible that you may have been a little heavy-handed on this go round?

I've peened bushings in a manner similar to what you're describing but only if the bushing pressed in with little resistance.

Have you been able to remove the warping?

Regards,

Bruce
 
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NEW65

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Thanks willie for the advice. I’ve always fitted the bushings from the outside of the plates with the anvil (or steel plate ) directly underneath the brass plates. I’ve never had any issues before. The steel plate stops the bushings and keeps them flush on the inside of the brass plates. I think I must have been a bit too heavy handed when I tapped these 3 bushings into position!
Obviously from what you say your method is the correct way of fitting them so maybe I should change the way I fit them now.
wow - I file in opposite direction ( after assessing the wear ) and centre using a broach. To avoid lots of time broaching away , I use a slightly undersized diameter drill bit for brass and then drill the hole out. I then slightly enlarge again until the bushing fits (tight fit as possible). Not many movements require 12 bushings. In fact I normally draw a line at 6 bushings as it uses too much of my time. However this was the only Hermle 0451 I had with a long reach spindle. Had it have been a short reach spindle I probably would have found a movement with less wear.
I have to say that nearly all weight driven Hermle movements especially the 1151 and 0451’s have lots of wear in the upper trains! Even the flywheels have sloppy pivots! I tend not to re bush flywheels (if I can get away with that). Even the new Hermle’s have sloppy pivots but happen to have round holes and that’s the difference.
Bruce - as I mentioned, this has never happened to me before. I’ve fitted hundreds of bushings and done a good job every time. I was therefore quite surprised when 3 of the gears had zero end play! In fact I couldn’t believe it! I thought the brass plates must have been slightly concaved !
Anyway to achieve some end play I chamfered the inside edges of the bushings (by hand )with a 10mm drill bit which produced a smooth bevelled edge and which allowed some end play of the gears! I tested the train out and it worked very well, driving the hammers at a very good pace.
I’m seriously thinking of getting a sherline milling machine as I’m bushing everyday now. I need something that saves time- messing around with files and cutting broaches is okay but takes too long and is more likely to lead to set backs.
Thanks everyone :)
 

NEW65

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Just ask you Bruce... you say you have peened bushings that have not been tight enough when fitted. Do you mean you have hit the bushing before fitting In place? Any bushings which I think are on loose side, I just (fractionally) decease the diameter of the hole by placing a ball bearing over the hole and using a light hammer. This works well every time.
 

NEW65

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Cheers Willie.
I never knew that. Thanks for adding this:)
I’d probably be better off with a bergeon bushing machine as much less complicated to use. And cheaper (I think).
 

Bruce Alexander

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Investigate all of your options but one can do a lot more with a Mill. More speed comes with practice. I use a Sherline. When using a three jawed chuck in the spindle I can work relatively fast. If I want to focus on obtaining as much precision as I possibly can (small pivots), I work with my set of Collets and sacrifice some speed.

In either case, I never had to recover from a poorly centered/placed bushing. Although it's not necessary, I use Loctite on all of my bushings in much the same way you peen your bushings to insure they are tight fitting. Just my own personal preference.

Jerry Kieffer has an online course available here if you are seriously considering a Mill: Products by Category
You could start a conversation with him if you have any questions before (or after) purchasing the course.

Just ask you Bruce... you say you have peened bushings that have not been tight enough when fitted
In the past, if I placed a bushing which didn't provide much resistance when pressed into the prep, I would place the inside surface against a smooth anvil and take a round nosed punch to the oil sink. One or two light taps was usually sufficient to ensure a tighter fit. I would then need to broach the inner diameter to size. This technique is described in the archives. I'll see if I can find a thread or two. As I mentioned, I still use Loctite routinely now, even though I bush with a Mill. Bushings have tolerances. Some fit tighter than others. I don't worry about it anymore.

A basic Mill set up isn't that expensive but the accessories do add up if you want to do more with it.

I'm glad that I chose to go this route although I'm sure a tool made specifically for bushing is fast and effective.

Regards,

Bruce

Edit: Here's a good Thread on the topic: Hole too large for bushing
 

Willie X

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In the meanwhile you could buy a #3 KWM reamer/D-cutter and a handle. This will allow you to nibble the worn holes back to center by hand, all one after the other. Then chuck that reamer in the ole drill press and finish all the holes, one after the other. This method is probably the fastest of all methods and can produce good quality work, with practice. It's also less than half the cost of a bushing machine. A few reamers, a handle, and a bench top drill press (all new) would set you back less than $300.

Willie X
 

Bruce Alexander

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New,

I forgot to mention that a Mill can also serve in a limited role as a Depthing Tool. With it, you can correct for previous bushings which have been placed off center. The last time I checked, a new, high quality Depthing Tool can cost in the neighborhood of $600.

A Mill can also be used to drill pivot holes off-center in blank (or solid) bushings. This may be helpful in cases where one needs to place a pivot hole close to the edge of a plate. I've used hand tools and a Drill Press with a hand tool adapter to bush plates. In my hands these approaches can not compare to the accuracy of a Mill.

It can serve as a high precision drill press without any additional accessories, and that's just the start.

Purchased new, a Bergeon Bushing Tool current lists for about $1,000... Bergeon Bushing Tool. I think it comes with everything you need to get going (bushings not included)

A new Sherline 5400 Deluxe Mill will set you back about $950, depending on where you shop. Some Dealers give significant discounts. This accessory kit will cost about $90, again depending upon who you deal with... https://www.sherline.com/product/2118-horological-milling-machine-bushing-and-depthing-accessory/. You would need that (or its equivalent) and a three jaw chuck at minimum to get up and bushing with a Mill.

You're already placing bushings so I have to assume that your basic tools and supplies are on hand.

As you mentioned, there is a steeper learning curve with a Mill, but once you get going, the basics of using one are really pretty simple. It can be slow going at first, but speed comes with experience and a high degree of accuracy is a given.

When compared to a Bushing Tool/Machine, buying into a Mill approach will cost more in terms of time and money, but not that much more. In return you potentially get much more.

Regards,

Bruce
 

R. Croswell

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I like to ensure that the bushings are quite tight. I use a light weight hammer with the plate sitting on an heavy duty slab of steel and tap the bushings firmly in place with the hammer.......However for the first time ever I noticed that 3 of the gears had no end play.....the bushings were dead flush with the insides of the plates? I thought for a moment that one of the brass plates must have been warped!..... :???: ..........could hammering in a bushing that is too tight cause the (hole ) plate to bulge? ..... Any thoughts??
Occasionally one finds a clock movement where the plates have been intentionally "formed" [read that bent if you like] to establish normal end shake. I have read that this was sometimes a factory adjustment, and could have also been done later for unknown reasons. Hammering the plate likely flattened the plate from its existing condition. If the bushings were truly flush That should not be the problem. If pounding the bushings caused them to bulge the surface of the plate then they are not flush. A straight edge can be used to verify if the bushings are flush or the plate warped.

I fitted 12 bushings in the plates.
There is no right or wrong number of bushings to install. Any clock that's run for a few decades will have some wear to every pivot and every pivot hole. There may be only a couple pivot holes that are worn badly enough to stop the clock from running, so I would guess that you did not need to install 12 bushings to make your clock run, but if you don't want to have to go back in and do more in the foreseeable future I think 12-14 is about average, at least for me. It doesn't take long to install another bushing while the movement is apart so why not do all that show signs of wear.

There is "the right way" to install a bushing and a lot of "other ways". Generally we are talking about bushing systems by KWM or Bergeon using commercially available press in bushings designed for these systems. Perhaps the best guide to just what is the "right way" comes from looking at how the system is designed to work. Simply put, the worn pivot hole is reamed to a precise under size for that systems manufactured bushings. The hole is reamed with a reamer that produces a hole perpendicular to the plate and the hole has straight parallel sides. These reamers will cut a true sized hole when rotated at slow speed by hand in a "machine" that ensures that the reamer is held perpendicular to the plate. The bushing is pressed in with a pusher that ensures that the bushing goes in the hole straight. The bushing is usually pressed in from the inside of the plate over a hollow stump to ensure that the bushing will be flush. Bushings that are installed this way require no hammering, expanding, or retaining compound, and will stay in place under normal use for the life of the clock.

Wow said; "I use a KWM machine. It is so much easier and more accurate than hand bushing and faster than setting up my mill for bushing." I agree.

RC
 

shutterbug

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I'll bet Willie hit it on the head when he suggested you may be bottoming out on your lower steel. The bushing goes through the plate slightly, and hits the steel. Then you, looking from the other side, figure it's just a tight fit and whack it harder until it's flush with the back plate. That forces the brass in both the plate and the bushing outward, mushrooming it.
 

Bruce Alexander

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Well RC, I've encountered bushings that were slightly undersized. This first happened when I tried using some bronze bushings but I've seen it occur with brass as well. The only way to know for sure is to press one into the prep. If you encounter a fair amount of resistance, everything is as it should be. If it doesn't offer a reassuring amount of resistance, then you have some decisions to make.

I do agree that if everything goes as designed, no further methods should be necessary.

As has been discussed elsewhere, there are special circumstances that may require more retention than is normally obtained with the KWM/Bergeon Systems. Seating a tight Gathering Pallet on an arbor where the opposite pivot has been bushed is an obvious example. Some folks take precautions not to apply force to the bushing, while others seek to tighten the fit of the bushing.

I likes my retaining compound. As far as I'm concerned, it's the cat's pajamas. :cool:
 
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R. Croswell

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Well RC, I've encountered bushings that were slightly undersized. This first happened when I tried using some bronze bushings but I've seen it occur with brass as well. The only way to know for sure is to press one into the prep. If you encounter a fair amount of resistance, everything is as it should be. If it doesn't offer a reassuring amount of resistance, then you have some decisions to make.
When a bushing goes in with little resistance it can obviously be one of two things - hole is oversize or the bushing is under size. I've never see this problem with genuine Bergeon bushings. They cost a bit more but I stick with name brand bushings. As I have said in the past Loctite retaining compound does no harm but isn't necessary for an initial bushing installation (otherwise the system manufacturer would have advised to use it). When I encounter a previously installed bushing that has to be replaced I do recommend using Loctite as you have said as "belt and suspenders". Are you using genuine KWM or Bergeon bushings?

RC
 
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Bruce Alexander

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I edited/added to my message above while you were responding RC.

I normally order from Butterworth. I've not encountered any issues with his bushings. They offer a good fit. As I recall, the Bronze Bushings that I first encountered with a loose fit were from one of the Supply Houses but honestly, I don't recall which. I was ordering from both Timesavers and R&M Imports at the time. My guess would be that they were from the later.

I also find the retaining compound useful in cases where I need to place two concentric bushings. This situation may occur when I want to replace an old Bergeon(?) bushing. The Bergeon's prep is too large for my typical assortment of KWM Bushing ODs (2.7mm). It's a matter of speed and convenience. If I think it is called for, I can, and have, turned custom bushings for the movement.

Regards,

Bruce
 
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R. Croswell

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............ As I recall, the Bronze Bushings that I first encountered with a loose fit were from one of the Supply Houses but honestly, I don't recall which. I was ordering from both Timesavers and R&M Imports at the time. My guess would be that they were from the later.

Regards,

Bruce
I started out using bronze Bergeon bushings years ago but seldom use bronze anymore, but I would think that the current production of bronze or brass would be made to the same tolerance. I wonder if anyone else has found under size bushings recently, either genuine KWN / Bergeon, or third party manufacturers?

RC
 

shutterbug

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I have not noticed any issues in the regular sizes. The sizes over 4mm seem to need less depth from the reamers, but that hasn't changed either. I always assumed it was the reamers rather than the bushings.
 

Bruce Alexander

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In the bronze bushing cases (or batch) I cited SB, the brass bushings I had in stock did not exhibit a looser than normal fit. As I recall, I tried a few of the bronze bushings in the prep and they were all loose. It was some time ago but I believe that in that one instance, I resorted to a brass bushing which worked out fine.

When I came across a Thread which discussed using a round nose punch, or ball bearing, to tighten loose fittings I went back to using the bronze bushings I had in stock, tightening them when needed. I seldom use bronze bushings anymore. I may still have a few from that batch.
 
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POWERSTROKE

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In the bronze bushing cases (or batch) I cited SB, the brass bushings I had in stock did not exhibit a looser than normal fit. As I recall, I tried a few of the bronze bushings in the prep and they were all loose. It was some time ago but I believe that in that one instance, I resorted to a brass bushing which worked out fine.

When I came across a Thread which discussed using a round nose punch, or ball bearing, to tighten loose fittings I went back to using the bronze bushings I had in stock, tightening them when needed. I seldom use bronze bushings anymore. I may still have a few from that batch.
From what I understand, bronze is slightly harder than the brass .i can’t see any reason to sacrifice a pivot for a harder bronze hole. I will always muse brass.
 

Bruce Alexander

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i can’t see any reason to sacrifice a pivot for a harder bronze hole.
There is some strong disagreement on this point but I tend to agree with you POWERSTOKE. In my opinion, it's a better use of your time and resources to focus on obtaining as smooth a finish as you possibly can on your pivot steel.

I think RC's approach of staying with original specs is almost always going to be the best way forward when servicing a movement.
 

POWERSTROKE

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There is some strong disagreement on this point but I tend to agree with you POWERSTOKE. In my opinion, it's a better use of your time and resources to focus on obtaining as smooth a finish as you possibly can on your pivot steel.

I think RC's approach of staying with original specs is almost always going to be the best way forward when servicing a movement.
I will have to agree with you to a certain degree. My reasoning comes from the fact that I’d rather re-Bush a hole that make a new pivot every time.
 

Bruce Alexander

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I will have to agree with you to a certain degree. My reasoning comes from the fact that I’d rather re-Bush a hole that make a new pivot every time.
That's part of the reasoning offered by John C. Losch, a highly respected Horologist. See this link for more details and context: 340-020 Options NB vs Bronze

I theorize that the differences in observations and preferences might be explained by the amount of airborne dust and abrasives found in a clock movement's operating environment.

Fine mechanical Watch Movements almost always use Jeweled Bushings. They are orders of magnitude harder than brass, bronze or even steel. These high-quality movements are sealed against dust and often are resistant to water. Their pivots/bearings hold up extremely well.

I have no proof of my theory. It's just a hunch on my part. There are quite a few "Brass vs. Bronze Bushings" Threads in the Archives if you're interested in reading more. As I mentioned, there are some strongly held differences of opinions on the matter. I don't think you'll go wrong if you stick with original specs.

Regards,

Bruce
 
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POWERSTROKE

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I hear you. For the most part, I’m sure I’ll stick with brass. Once most of these movements are fixed, they should run for a long while
 

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