Using glass for bushings

Discussion in 'Clock Construction' started by karlmansson, Nov 8, 2016.

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  1. karlmansson

    karlmansson Registered User

    Apr 20, 2013
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    Hello!

    I'm slowly working my way towards constructing a clock from an existing motion work. I went over my plans with a watchmaker friend of mine and he pointed out that my plan of straight motion works might not be such a good idea. Apparently a student at the school where he teaches made such a clock that developed meshing errors. Wether it was from construction error or wear wasn't clear but it didn't work, is the bottom line.

    Construction errors will have to be dealt with by careful construction but the wear supposedly stems from all the wheels having the same load direction and so the error from wear accumulates at the escape wheel. So I thought I might use jewels to reduce the effects of wear!

    Jewels in these sizes seem to be close to impossible to find and those close are expensive. I thought I might try to grind glass bushings to suit my needs, from plate glass. Does anyone here have any suggestions or deterring advice on using glass for bushings? It seems to suit my needs, it's hard easily obtainable and present in sections more easily worked than lapidary blanks.

    All help appreciated!
    Karl
     
  2. Tinker Dwight

    Tinker Dwight Registered User

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    Jewels are used to reduce friction not to reduce load wear.
    Tinker Dwight
     
  3. karlmansson

    karlmansson Registered User

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    Well, yes...? And friction causes wear. Worn jewels are much less common than worn brass bushings in my experience. I also see that LeCoultres table clocks with straight motion works have jeweled bushings. If I can reduce friction, and thereby wear, wouldn't it extend the service interval and function of the clock?
     
  4. Phil Burman

    Phil Burman Registered User

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    What's the significance of "straight motion works"

    Phil
     
  5. karlmansson

    karlmansson Registered User

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    Hi Phil!

    I should have elaborated on that... In line motion works, in that all wheels will have their bushings in a straight line between barrel arbor and pallet arbor.
     
  6. Tinker Dwight

    Tinker Dwight Registered User

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    You can use less drive force with jewels and have less wear.
    It is not friction that is causing wear. It is the dirt that gets
    in the oil plus the force between the surfaces.
    Don't equate friction with wear.
    Tinker Dwight
     
  7. dAz57

    dAz57 Registered User

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    Personally I don't think glass is hard enough, you can get sapphire watch crystals in various thicknesses, cut your "jewels" from that, what about just using micro ball bearings.
     
  8. tok-tokkie

    tok-tokkie Registered User

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    I had also considered using glass as a 'jewel'. My idea was to use Pyrex capilliary tube & simply cut short pieces off. I found suitable tube available for a 1 second pendulum clock train. I did not proceed with the idea.
    For small ball bearings Google Boca Bearings in California. Excellent data on all their bearings - sizes, load ratings etc. For clocks best are all ceramic but they are expensive - especially when shaft is <3mm. I use hybrid bearings - stainless steel races with ceramic balls. Wash all the grease out - soak them in engine cleaner and spin them in running water.

    For commercially available jewels there is Swiss Jewl in USA http://www.swissjewel.com/2/ring_jewels Trouble is they only list imperial sizes.

    Another US source http://birdprecision.com/bearings2/Ring_jewel.pdf

    There is a very informative Wiki post (sourced from Bird I suspect). https://en.wikipedia.org/wiki/Jewel_bearing
     
  9. karlmansson

    karlmansson Registered User

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    In all fairness, the grit that enters the oil also adds to the friction, causing wear. Of course, at Clock with dried up, Clean oils can fail to run where the same Clock with fresh oil, contaminated with abrasives, will run but wear itself down. I Think there is a difference in those cases though as the first instance is adhesion and the second friction.

    Yes, ball bearings are probably the way to go! But why wash the grease out?
     
  10. karlmansson

    karlmansson Registered User

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    I keep reading about butter bearings when searching for ball bearings for this application. Are they a good and price efficient alternative in your expereince?
     
  11. tok-tokkie

    tok-tokkie Registered User

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    The grease is washed out for two reasons. Firstly for endurance. The grease will harden as the solvents evaporate over the years. Secodly to reduce the torque. Without grease the bearings spin much more freely.
    Here is a link to a good paper about them. http://www.dg-chrono.de/fotohome/images/2010-03/55a4f31df675b3ee045a520e5.pdf

    Butter Bearings are conventional carbon alloy steel minature ball bearings. They get their name from Mark Butterworth who supplies them. He is active on this site. http://muscatinejournal.com/news/local/time-is-money-mark-butterworth-knows-exactly-how-much-time/article_d181102c-34e5-11e1-8e4a-0019bb2963f4.html
     
  12. John MacArthur

    John MacArthur Registered User
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    I'm in the process right now of making jewel bearings for a regulator I'm almost done with.

    Cutting the raw ruby boule, and then roughing it round DSCN0716.jpg DSCN0708.jpg


    Grinding round DSCN0711.jpg

    Drilling and cupping DSCN0709.jpg DSCN0712.jpg

    Grinding the face, and the apparatus DSCN0715.jpg DSCN0714.jpg

    The process, while somewhat lengthy, isn't impossible, even with old, fat, beat-up fingers. I've made quite a bit of the tooling myself over the years. The next stage is polishing the outside edge, front face, and oil cup with finer and finer diamond paste. After that, while the jewel is still concentric on the brass tube, I'll size and polish the inside bearing surface with a small needle shaped polisher I built. Finally, I'll reverse the jewel on the tube, and grind and polish the other face. I'll post pictures as I complete this process, if there is interest.

    I guess the point is to encourage the OP to take a swing at what you want to do, even if you use glass as the material. The raw ruby isn't that expensive, though, and makes a really attractive classic bearing.
     
  13. cmnewcomer

    cmnewcomer Registered User

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    John,

    I'm very interested in the process you have been using to make your own jeweled bushings. While I have contacted the suppliers listed previously, they did not really have the sizes I wanted and didn't really want to work with a hobbyist.

    If you have time, please provide more details along with suppliers for the raw material and type/grade if that's the correct terminology.

    Best Regards.

    Carl
     
  14. glenhead

    glenhead Registered User
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    Yes.

    Glen
     
  15. John MacArthur

    John MacArthur Registered User
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    Carl -- the boules can be bought at gemcutter.com - a quick google search brings up lots of others. Diamond drills can be bought at Rio Grande Albuquerque, Lasco Diamond, and MSC. The diamond paste I also get from Rio Grande Albuquerque riogrande.com -- I use 325 grit for rough grinding, 1200 grit for smoothing, and 14000 grit for final polishing.

    There is a good write-up on the process in George Daniels "Watchmaking"

    Best of luck,
    Johnny
     
  16. cmnewcomer

    cmnewcomer Registered User

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    Johnny,

    Thanks for the additional information. Looks like I will need to pickup a copy of Watchmaking to get acquainted with the process and terminology.

    Are the synthetic stones good for this purpose and if so, what type would you recommend?

    Best Regards.

    Carl
     
  17. Tinker Dwight

    Tinker Dwight Registered User

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    I'm curious if the red ruby is any better than the just
    clear synthetic sapphire? Is it just for looks or all about
    the same?
    Tinker Dwight
     
  18. John MacArthur

    John MacArthur Registered User
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    Carl -- Yes, the synthetic rubies are actually better for clock jewels. I used some "river" ruby many years ago, and made several fine pallets and some good jewel bearings, but the fracture planes weren't always apparent. I wound up with several bearings that had quite obvious fractures embedded within them. In the Gemcutters site, and likely others, you can choose between dark and not-so-dark stones. I've always liked the darker ones, but all ruby and sapphire is basically the same material (aluminum oxide, or corundum). Sapphire makes good-looking pallets, and I have another set of pics showing that process. "One of these days" I'll assemble the whole series into a single thread on making a high-grade regulator.

    You'll notice that I use a gem-cutting wet diamond blade, very thin, to cut the initial slabs from the raw boule. I use a jewelers "dopping wax" to hold the boule onto a plate of thin glass (welders cover glass, or microscope slide) during slicing and subsequent cutting of the slab into smaller pieces. It also holds the jewel onto the 1/8" brass tubing, for the other work. I also have a number of laps for each grade of diamond paste. Some run directly on WW mandrels, and some run on the high speed spindle as the jewel rotates in the lathe head. I've made all these from copper plate, which being soft and ductile, holds the diamond. I have one watchmakers lathe only used for abrasives, including diamond paste. If you only have one lathe, you'll need to be pretty careful to not contaminate the bearings and slides. Over the years, I've accumulated four, but I'm still pretty careful with the dedicated abrasive one.

    The further polishing and all important inside lapping to size and polishing are coming up, and I'll post pics as that comes along.

    The Daniels book has been a constant source of inspiration and information over the last 30 years - I can't recommend it highly enough.

    Best of luck,

    Johnny
     
  19. John MacArthur

    John MacArthur Registered User
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    "I'm curious if the red ruby is any better than the just
    clear synthetic sapphire? Is it just for looks or all about
    the same?
    Tinker Dwight"

    Tinker -- all ruby and sapphire are corundum (aluminum oxide), and so are the same hardness. The color is from very slight amounts of impurities. I guess I'm just a traditionalist. They are all equally good.
    Johnny
     
  20. karlmansson

    karlmansson Registered User

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    Thank you for all the great input! I started out regarding glass as harder than it is I think. Something about leaving hardened steel "glass hard" I think made me make the assumption. My long term goal is to make a watch from scratch and it would be very rewarding to also be able to make the jewels I think. It calls for additional tooling and a whole lot of trial and error before I get anything worth using. I don't have a lathe to spare at the moment either... Later!

    I think ball bearings will be the way to go. But aren't they designed to be lubricated? I'm thinking they will wear much faster without lubrication. I know this guy can be a bit salty so no offense to those suggesting washing the lubricant out. It just made me think of this video: https://www.youtube.com/watch?v=uD7Lzv5fWhs

    Best regards!
    Karl
     
  21. Jim DuBois

    Jim DuBois Registered User
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    You can find a lot of perhaps relevant information at https://www.bocabearings.com/ball-bearings-in-clocks Rex Swensen has done a lot of work on the subject, so no need to reinvent the wheel....
     
  22. karlmansson

    karlmansson Registered User

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    Thank you Jim!

    I was provided with the link to Boca Bearings earlier but did not manage to find the page you linked. Very informative! I Think I've learned all I need on the subject for now. Thank you to everyone who contributed!

    Best regards
    Karl
     
  23. jhe.1973

    jhe.1973 Registered User
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    Darn right there is interest!

    I had the opportunity/privilege of visiting Johhny in his shop last year and he was very helpful in explaining this jewel making process. But do you think I would remember all of the steps?

    :screwball:

    Nope not me. So please, pretty please keep us updated on your progress and I am so glad to hear that you have a "One of these days" write-up planned.

    I believe that there will be a LOT of interest in a thread that would showcase your craftsmanship and be inspiring to all as well.

    :thumb:
     
  24. John MacArthur

    John MacArthur Registered User
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    Thanks for the kind words, Jim. I'm working on these between other stuff - they involve a lot of slow going. I *will* get them on board, though.

    Johnny
     
  25. Jim DuBois

    Jim DuBois Registered User
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    Rhetorical question. Why have millions of watches been built with jewels and none built with glass bushings? That alone would give me pause, as glass is a lot cheaper than sapphire or diamond or other jewels used in watches. And capitalists will always be capitalists.....so if glass was a good substitute for jewels and it was much cheaper would it not have been used in millions of watches? I know little to nothing about watches but I do pay attention to the human condition if you will. It is my passing recollection that the jewels used in watches were selected for their ability to accept a fine high polish which then allows much reduced friction when fit properly to hard steel pivots. You all have covered this nicely in comments above. I am also aware that in some conditions glass can be very abrasive, even polished glass. There are of course other characteristics of jewels versus glass where jewels may fair best. In any event I would error on the side of caution and buy synthetic sapphire boules and stay away from glass. The cost of the synthetic products seems pretty reasonable to me. The cost of a jewel, no matter of what it is made is more in the time to make it than it is in the material.
     
  26. ccwk

    ccwk Registered User
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    I will second that !
    To John and the others - Thanks for sharing your experiences
    Much appreciated Conwae
     
  27. karlmansson

    karlmansson Registered User

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    Of course I realize that synthetic ruby would be superior to glass, considering how long it has been used and with what success. My question came from a place where I had trouble finding jewels of the size I required and thought that glass would be more easily worked and more easily obtainable than ruby boule. I'm interested in learing lapidary work as well so glass might be a good place to start out.

    For the application I asked about originally I think ball bearings are the way to go in any case. I do however appreciate the input from everyone and I am also looking forward to a more in depth look at making jewel bearings, when it come around!

    Best regards
    Karl
     
  28. Bill Ward

    Bill Ward Registered User
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    I'm a bit dubious that a straight-line train would exhibit more problems with pivot location errors than another arrangement. Recall that the force applied to a pivot by a wheel tooth is (mainly) at right angles to the line of centers, though there is some pushing away of the pivot too (which varies with the tooth contact angle through tooth contact). And sure enough, what we see in worn plates is an oval hole whose long dimension is at about a 75-80 degree angle to the line of centers. Probably the worst arrangement, vis-a-vis pivot wear & cumulative position error for a train would be one where the wheels are at this this 75-80 degree angle to the line of centers; which is not always too different from what we usually have in existing clocks! Timepieces generally have train layouts that condense their dimensions to fit their cases.
    One reason that glass has not been used for bushings is that it's so brittle & breakable (compared to sapphire). But probably the real reason is economics: it's a lot easier to sell something for a high price if it's made with rare jewels, rather than broken bottles.
    But consider that brass bushings are considered sacrificial; it's a lot easier to re-bush than to repivot.
    Butter Bearings are really more a system for repair, than just simple bearings. They are sold in sets for specific repair jobs, e.g the Hermle floating balance movement. The pivots fit loosly into the bearing ID, which avoids precision alignment problems. The bearings are as easily set as brass bushings. This enables movementsw with plated pivots to be salvaged, and used, probably, another century- which is a lot more than they've lasted so far! And if you're worried about your rep long after you've been in the ground, just include an extra set or two in the case- that'll certainly earn you a prayer of thanks from some future clockmaker!
     
  29. Accutronica

    Accutronica Registered user.

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    Very interesting thread. I can't wait to see more.
     
  30. THTanner

    THTanner Registered User
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    Glass is actually a very viscous liquid. Even a small piece of glass will change shape over time under constant pressure. Large windows get thicker at the bottom versus the top under the force of gravity. I don't know how long it takes in terms of size and pressure, but if you are wanting to use glass to make a long lasting bearing you are probably not going to be happy after a few years.
     
  31. Phil Burman

    Phil Burman Registered User

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    This is incorrect, read:

    https://www.scientificamerican.com/article/fact-fiction-glass-liquid/

    Phil:)
     
  32. Accutronica

    Accutronica Registered user.

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    I agree, but it might be good for a temporary fix.
     
  33. THTanner

    THTanner Registered User
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    #33 THTanner, Jan 30, 2017
    Last edited by a moderator: Dec 29, 2017
    That is a discussion about "Super Cooled Liquids" - and states "Like liquids, these disorganized solids can flow, albeit very slowly. "

    Newer research is showing more clearly when and why glass molecules do move and what constrains these motions. "[FONT=&quot]The movement of the glass molecules slows as temperature cools, but they never lock into crystal patterns. Instead, they jumble up and gradually become glassier, or more viscous." from [/FONT]https://www.sciencedaily.com/releases/2007/08/070809130014.htm

    [FONT=&quot]"The problem with glass-forming materials - which include plastics, alloys and ceramics in addition to everyday "glass" - is that there is no obvious transformation. On cooling we cannot definitively say yet that glass has become a solid." This study takes if further and discusses why some areas in a piece of glass appear more solid than others and why some are less viscous. [/FONT][FONT=&quot]
    [/FONT]
    http://www.iflscience.com/chemistry/glass-solid-or-liquid/

    Under stress it gets a lot more complicated.


    "You may be surprised to learn that glass is an elastic material on the atomic level. This means that under stress, glass will deform due to the nature of its atomic bonding structure." "The elastic nature of glass is described by its elastic moduli. These moduli tell you a lot about how much a glass will deform under stress and in what direction it will deform. They are defined by the relationships between different directional elements of stress and strain. Three important and commonly used elastic moduli are Young's modulus, Poisson's ratio, and the Shear modulus."

    [FONT=&quot]And there are very different kinds of glass with different properties that affect how much they deform under stress. The addition of silica, soda lime silicates and borosilicates changes the properties such as flexibility and sheer resistance. But glass does "flow" under stress at the molecular level, albeit very slowly and sometimes returns close to its previous shape when the stress is relieved.

    [/FONT]
    This study talks about the changes in the chemical bonds that allow the molecules to flow under pressure and how it occurs. https://www.researchgate.net/publication/233681672_Deformation_of_Sodalimesilica_Glass_Under_Pressure_And_Stress_by_Molecular_Dynamics_Simulation

    It is a poorly understood process with lots of variables. But current research shows that glass molecules do flow under stress at normal temperatures.

     
  34. Tinker Dwight

    Tinker Dwight Registered User

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    Regardless, glass is too easily scratched. It is not particularly hard.
    Anyone that has had the misfortune to have the rubber come of a
    wiper blade. In just a few minutes, there are scratches in the glass.
    I doubt it would work well as a bushing.
    Tinker Dwight
     
  35. Phil Burman

    Phil Burman Registered User

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    TH, in the link I gave Robert Brill, an antique glass researcher at the Corning Museum of Glass in Corning, N.Y. says:

    "Furthermore, cathedral glass should not flow because it is hundreds of degrees below its glass-transition temperature, Ediger adds. A mathematical model shows it would take longer than the universe has existed for room temperature cathedral glass to rearrange itself to appear melted."

    The reference you gave relates to glass behaviour under stresses in the GPa range, that's 145,000 psi. Most anything will flow under that kind of stress, however I doubt a clock bearing will see those kind of numbers under normal usage.

    Phil:)
     
  36. John MacArthur

    John MacArthur Registered User
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    Follow-up on my jeweling project.

    attachment.jpg
    attachment.jpg
    Final polishing the holes of the jewels

    attachment.jpg
    The outcome, burnished into a chaton with bezel, and with #0-80 screws

    attachment.jpg
    Mounted in the back cock
    attachment.jpg
    The fully jeweled escapement, finally. It seems eager to run.

    More as it comes.
    Johnny
     

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