Delrin-AF bushings in wooden movement 7 & 10 year update

Discussion in 'Wood Movement Clocks' started by R. Croswell, Nov 26, 2016.

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  1. R. Croswell

    R. Croswell Registered User
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    This is an update on my experience using Delrin-AD bushings in wooden clocks. All of the clocks that I have bushed with this material are, as far as I know, still running. This Daniel Pratt Jr. clock has a typical Terry type wooden movement by E. Hotchkiss. Ten years ago I installed a few Delrin-AF bushings in this clock, then seven years ago I installed more Delrin-AF buishings mostly in the going train. This week I had a problem with the strike making a racket and not always working so I stripped the movement for inspection and installed 8 additional Delrin-AF bushings.

    Upon inspection, the previously installed Delrin-AF bushings showed no perceptible wear after 7 or 10 years and the pivots in these bushings were clean, smooth and bright. Two pivots that were running in the original wooden holes were badly scored and required replacement The escape wheel brass bushing was dry dirty. The movement is back together and installed in the clock and running fine. I was very pleased to how well the Delrin-AF bushings have held up. I have five wooden works clocks of my own that I try to keep running all the time. This is the first one that I've had a reason to take apart since installing bushings - a problem unrelated the previous bushing work.

    I really need to try to remember to oil that one brass bushing and the verge more often. They are all strong runners, this one is using 2.5 lb. weights.

    RC
     

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  2. David S

    David S Registered User
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    Great update RC. I assume that you are running the Delrin bushing dry.

    I have mentioned before that I have started experimenting with some IGUS polymeric bushings in an old weight driven brass plate movement I have, but have nothing to report yet. I tend to think that oil in some of these pivots is more of a dust / dirt magnet than being all that useful. The stuff I am working with is impregnated with some sort of solid lubricant as I understand it.

    David
     
  3. R. Croswell

    R. Croswell Registered User
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    Yes, that's correct; I'm running the Delrin-AF bushings dry. The material has a good coefficient of friction. The ones that I have bushed 100% test run OK on 2 lbs. and the time side will run on less than that but does not have the power to trip the strike train into warning. I believe that Delrin-AF is compatible with oil but introducing oil would attract dirt and require regular cleaning and oiling, and there would be the issue of excess oil soaking into the wood. I seriously doubt that oil would improve the operation or longevity of the clock and may indeed shorten pivot life by attracting abrasives. We really need to see 30 and 40 year tests but I won't be around to see it.

    How are the IGUS bushings working out?

    RC
     
  4. Kevin W.

    Kevin W. Registered User

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    That is good news Bob, on the Delrin AF bushings, i find similar things to with the wooden movement i am working on, time side i have running on 2.5 pounds, running with plenty of power. I will do a write up when i am finished the movement i am working on.
     
  5. David S

    David S Registered User
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    Are you using Delrin bushings Kevin?

    David
     
  6. David S

    David S Registered User
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    RC I got some bar stock from IGUS so I could machine my own sizes. My concern was whether they would hold in 1.6 mm thick plates. So far I have installed some,and when I remember I have been winding the clock, but during the summer we are not here much.

    I would suggest that you may want to contact them and get some of their bar stock. While I do have some delrin, I figured that since these are engineered for bearings specifically with solid lube as well, they should be a better choice. The stuff that I ordered was a light beige color and it machined beautifully. And it is not very expensive.

    David
     
  7. Kevin W.

    Kevin W. Registered User

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    Hi David, yes i am using Delrin AF rods stock to make bushings for my wood works clock. I like it to work with turning and drilling it.
     
  8. R. Croswell

    R. Croswell Registered User
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    Your 1.6mm plates would be brass I assume. Retaining the bushings is a concern with any material. Typical brass bushings rely on skin friction (in brass plates) to hold them and the brass being dimensionally stable the retention is good over time. "Plastics" in general tend to deform to some extent over time under pressure. I don't know how the IGUS material will hold over time pressed into brass. I believe that Delrin-AF is probably too soft for a heavy friction fit. The anti friction properties of both materials I believe could make long-term retention a concern. Delrin-AF, as far as I know, is sold in basic shapes that others machine into specific parts. I believe it is intended for use as a bearing material but I have not seen anyone selling bearings made from it to the market place. For wooden plates, I typically turn the Derin-AF bushings to 0.176" OD (matches a Bergeon reamer size) and then I file a notch in the side. I set the bushing with a bit of epoxy which fills the notch and bonds to the wood to 'lock' the bushing, which is a light press fit in the hole. I'll be interested in how you make out with the IGUS material in the thin plates.

    The problem with trying these and other materials for clock bushings is that it takes some years to build enough confidence to recommend their use to others or to use them in someone else's clock. If I come across a couple wooden movement clocks at 'the right price' I may experiment with some IGUS stock, but I live in a very small house with 90+ clocks so don't know where I could put them plus to prove anything I would need to run them all the time. I already have my five woodies and a half-dozen or so other clocks that have to be wound every day, so please keep us informed about your results. I'll also be interested in Kevin's results.

    RC
     
  9. john e

    john e Registered User

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    I love working delrin..I picked up some black and some natural in .375 rod stock.

    One thing I absolutely love, is that when I chuck some in the lathe and run a drill from the tailstock, the resulting hole is a very tight fit on the back end of the same drill bit. I use one bit in the lathe, another in the drill press backwards, and can do further work on the drill press. I recently made 8 delrin spacers for an 8 bell assembly, as the museum piece actually had faucet washers installed for spacing the bells...hall of shame stuff.

    I guess I can make my natural delrin available for the museum repairers for overholed wooden movements based on RC's good results.

    Thank you for the update.

    btw, I just picked up some lignum vitae, has anybody considered that in lieu of delrin?

    John
     
  10. R. Croswell

    R. Croswell Registered User
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    Lignum vitae should be a good option. I believe others here have recommended it. Don't know how it compares to Delrin-AF. I just made an S2 arbor with both pinions from a single piece of black Delrin using just a lathe (no wheel cutter). Yeah, it will be very obvious, but it's just a movement I robbed the original part for a customer. Not ready to show it until I get time to cut a wood wheel to fit it to.

    RC
     
  11. john e

    john e Registered User

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    The delrin flexes a lot more. I've been researching hardwoods for my Clayton Boyer "Tiempo", as I am starting to re-aquire my life after two years on hold. Examination of the Janka hardness results for woods is quite illuminating. Lignum Vitae measures 4500 lbs and is the hardest wood on the chart. Cherry comes in at 3190, mahogany at 2600, Maple at 1450, walnut at 1010.

    I'm working on designing the tips of the escape wheel and the pallet surfaces in Lignum vitae for hardness against impact as well as lower friction..should be interesting.

    Have you tried a deflection test on the arbor to see how much it gives for the weight? How will you capture the wheel and pinion, just pinning?

    John
     
  12. Tinker Dwight

    Tinker Dwight Registered User

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    The thought of using Delrin on a brass plate clock is interesting.
    When my brother was building a car for SCCA racing, He turned
    Delrin for bushings on the suspension. We never saw any creep
    that I could say that the load was deforming them.
    What I'm thinking about also is on plated pivot movements, one could strip
    the nickle platting off and install Delrin. One could make a shoulder
    on one side and a groove for a clip ring on the other.
    Just some thinking.
    Tinker Dwight
     
  13. R. Croswell

    R. Croswell Registered User
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    Probably a combination of pinning and glue. When I install the bushings I file a couple notches in the side that will fill with the epoxy glue. The glue will bond well to the wood and the notch will make a mechanical lock even if the glue doesn't bond well with the Delrin. The part didn't seem flex very much in the lathe and it will have steel pivots so being the 2nd arbor with only 3 lbs. on the first I don't think there will be an issue.


    Tinker, I'm not sure how well it would work with turned plated pivots but should work if you can keep it in place. I have one test clock where I just turned the plated pivots and bushed with regular bronze bushings. I've run it continuously (just heard it chime) for 8 years of so without any issues. I like playing with different methods and materials but unfortunately it takes years to know how well something holds up. Just turned 75 a few minutes ago so there's a good chance my Delrin-AF bushed clocks may last longer than I will!

    RC
     
  14. Kevin W.

    Kevin W. Registered User

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    Happy Birthday Bob, always glad to read what you have been working on.
     
  15. R. Croswell

    R. Croswell Registered User
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    Thanks.
     
  16. John P

    John P Registered User
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    Bob, I contacted you some 9=10 years ago regarding the use of delrin bushings in a Terry clock the was and is in a Historical home in the Kings Mountain Revolutionary park.
    We made bushings for almost every wheel, front and back. No oil was used in these bushings.
    The clock is still running to this day with no service whatsoever.
    Since then, I have used this material to repair several WW movements without a hitch.

    John
     
  17. R. Croswell

    R. Croswell Registered User
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    That's great to know. It is important to know when others have success (or failure) whit new materials and different methods.

    RC
     
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