mockup of Synchronome build

Discussion in 'Clock Construction' started by John Robinson, Dec 19, 2013.

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  1. John Robinson

    John Robinson Registered User

    Nov 25, 2013
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    Howdy, here's pics of my Synchronome mockup,just got to this point today! WOOT!!!! .. still have lots to do, detent roller, stops and wiring posts, all the details... mockup4 19dec13.jpg mockup619dec13.jpg
    john robinson
    retired mechanician
    world land speed record holder Bonneville Salt Flats
    H/GCC dodge colt 144.396 MPH
    1967 BSA Victor 107.371 MPH at Bonneville
    USAShooting Air Pistol National Record holder
    Antarctic Ice Core Driller 3,331.538 meters
    Grandpa
     
  2. Allan Wolff

    Allan Wolff Moderator
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    John,
    Looks like an interesting project. Keep the pictures coming.
    Allan
     
  3. tok-tokkie

    tok-tokkie Registered User

    Nov 25, 2010
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    I have just been reading about them again in Woodward's book, My Own Right Time. I had not realized the impulse stuff was so far down the pendulum. Lovely solid & rigid structure everywhere.
     
  4. John Robinson

    John Robinson Registered User

    Nov 25, 2013
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    Howdy, here's today's work, countersunk bolt/stud holes where stops and power posts attach, both front and rear of clock back, installed the stops and power posts, cleaned up a couple of places on the cast iron. My punch list is short, find a spring for the magnet arbor, fix a looseness problem with the gravity arm pivot, hmmm I think that's it... well... paint, order batteries,and I still have to build the heat treat oven for the Invar pendulum rod. 2nd assembly 21dec13.jpg this picture is without the pendulum.. so my project is coming along quite nicely..
     
  5. tok-tokkie

    tok-tokkie Registered User

    Nov 25, 2010
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    You have to heat treat an Invar pendulum rod? I have not seen that mentioned before. Care to detail what has to be done?
     
  6. John Robinson

    John Robinson Registered User

    Nov 25, 2013
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    QUOTE=tok-tokkie;830263]You have to heat treat an Invar pendulum rod? I have not seen that mentioned before. Care to detail what has to be done?[/QUOTE]

    Howdy,

    Riefler annealed his Invar pendulum rods at 250F, for 20 days? while vibrating the rods every 4 hours .. sorry, I do not have the source for this, this is from memory.

    Matthys in "Accurate Clock Pendulums" states that non heat treated Invar is 1 1/2 to 2 times higher than the rated thermal expansion coefficient. A three step heat treatment gives the maximum dimensional stability over time, it typically gives a thermal expansion coefficient of about half the rated value.
    1) 1500*F for 30 minutes per inch thickness, water cool. in an inert atmosphere furnace
    2) 600*F for 1 hour air cool. open air furnace ( not inert)
    3) 200*F for 24 hours, air cool. open air furnace.
    all the above from Matthys.

    I plan on using the above treatment with variations:
    Do a furnace cool after the time spent at 600*F and 250*F, by leaving the rods in the furnace and just shutting it off and let it cool to room temperature, this should take 10-12 hours or so at 600*F, and probably 3-4 hours from 250*F.
    I also want to increase the number of times at 250*F to 20 or so..... (or I'll stop when my electric bill really starts to hurt... )

    I also want to cryogenic treat the rods when the heat treat process is done.

    I have not figured out how to vibrate the rods yet...just bang them on the bottom ends? tap lightly the whole length? the bang the ends will be easy, my furnace will have a bottom door.

    As far as I have been able to find, nobody has the directions about how to do Rieflers vibration heat treatment; to say "vibrate the rods", is not directions on how to do it.
    If anybody out there does have this info, about how to replicate Rieflers actual Invar heat treat process for his high accuracy pendulums (His J-1 observatory pendulums) please post it.

    thanks, drive carefully

    john robinson
    mechanician
    world land speed record holder Bonneville Salt Flats
    H/GCC dodge colt 144.396 MPH
    1967 BSA Victor 107.371 MPH at Bonneville
    USAShooting Air Pistol National Record holder
    Antarctic Ice Core Driller 3,331.538 meters
    Grandpa
     
  7. Allan Wolff

    Allan Wolff Moderator
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    Mar 17, 2005
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    Hi John,
    It would be interesting to see before and after measurements of the invar coefficient of expansion to verify the effect of the heat treating process.

    A somewhat simpler heat treat process is found on Ed Fagan's website invaralloy.com

    Heat Treating Invar for Lowest Optimal Dimensional Stability
    For the optimal dimensional stability, the recommended heat treating method for Invar Alloy is to heat at 1500°F (815°C) for 30 minutes per inch of thickness, water quench and reheat to 600°F (316°) for 1 hour, followed by air cooling.
     
  8. John Robinson

    John Robinson Registered User

    Nov 25, 2013
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    Howdy,
    I am aware of different methods in the heat treating of Invar, and choose to do the more involved one and then add further steps. Riefler went to extraordinary lengths when he built his pendulums, and I believe the results show his methods worked. I hope to replicate what I know of them.
    I have built a test station for Invar rod, but do not have the numerical data from the single test I did (that piece of scrap paper got thrown out).
    The station comprises of a 2x2x1/8 square steel tube with a welded fixture to hold one end of the 5/16 rod to be tested. The other end has a ball bearing fixture for the rod to ride on, and a .0001 indicator to record the expansion of the heated rod. I used a standard medical heating pad to warm 1 foot of the rod. I insulated the steel test station from the heating pad. I then compared that result with the result of test of a 5/16 1018 steel rod. The 1018 rod had more expansion. That was my test, at the time I was only interested in the comparison.
    I have 2 Invar rods from 2 different sources with test certificates that show they are not the same batch, so it would be interesting to see if I can record differences. As I recall from the single test I did, I was not convinced that I could get repeatable data.
    I probably should redo the experiment and record the differences. However, when I retired a couple of years ago, I had "The List Of The Lists, Of Things To Do"....I have found that the lists just seem to be getting added to, as I find other things to do that were not on the lists..........
    I'll see what/if/when I can...
    Thanks, drive carefully.
    john robinson
     
  9. Jim DuBois

    Jim DuBois Registered User
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    Jun 14, 2008
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    I offer the following thoughts just for purposes of discussion;

    There have been a number of interesting papers written over the last several years regarding precision mechanical timekeeping. Some of the hypothesis made may be useful when discussing pendulum and suspension technology. It has been stated pendulum suspension compensation, or perhaps more correctly stated pendulum stability, due to changes in rod length was obviously much more of an issue before the advent of modern central heating and cooling. Many homes will maintain temperatures of less than 1 degree variance day to day, month to month. It has been suggested by people more astute than me that the first priority is maintaining consistent temperature within a clock case before considering compensation or moving to more exotic materials for the suspension rod. If the temperature never varies more than say .1 degree F then what is the resultant change in timekeeping of the planned device? I have seen tables comparing wood (well sealed), carbon fiber, quartz, Invar, and normalized steels compared in a more or less stable temperature enclosure. Length changes of course followed already published expectations, but when compared to other variables in the impulse mechanism, barometric changes, humidity changes , "Q" of the pendulum, rigidity of the support structure, vibration, air motion and so forth, all seemed to generate larger and less predictable error than minute changes in length due to very limited temperature changes.

    Given your history of competition and success in some very complex environments I suspect I am only mentioning things you are already aware of and have considered, but I mention them anyhow, just in case others may be interested.

    Without searching out the requisite white papers, my recollection some of the best results (non vacuum cased) have been obtained by using a pendulum rod of fuzed quartz, a bob made of the most dense material available, tungsten being preferred, made in an elliptical/football shape, supported on a concrete base and column, running in a very tight wooden case, temperature controlled in the case, with the pendulum being impulsed by a "disconnected" power source. Synchronome is an excellent power source for impulsing the pendulum.

    May I inquire as to the source for your frame? Looks like it is coming along very well. You are building one of the mechanisms I have always wanted to own or build.....but have not done so....yet....

     
  10. John Robinson

    John Robinson Registered User

    Nov 25, 2013
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    Howdy,
    I picked my cast iron frame up from a British (ebay.co.uk) seller 5 years ago. Last month I bought another on Ebay, also from England. This one however, has a cracked and rewelded A frame, it is usable, and once it has been annealed I would not hesitate to use it.
    The company selling them has not had any in stock since before I bought my first one. I am in contact with them every 6 months or so, trying to place an order for one, no joy so far. Perhaps if there were more requests to them, they might consider restocking.
    www.collegeengineering.co.uk is the website, they have casting kits for machine tools (a gear hobbing machine) and also CZ120 engraving brass. No affiliation with them, but I've bought stuff from them and it is good quality.
    I built my clock using the Engineering In Miniature magazine construction article, it had instructions for both the cast iron back, and for fabricating one from steel. This rereads like it is familiar to me, did I already post this statement here? hmmm, getting old....

    anyway, I've a dinner to attend, I'll get back about the rest of your questions later, thanks drive carefully..
    john robinson
     
  11. tok-tokkie

    tok-tokkie Registered User

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    Thanks for detailing the heat treatment method and the source of the methods.
    I have tried to measure the thermal expansion of my carbon fibre pendulum rod - sadly I tried doing it horizontally so it sagged more than it expanded! Will do it again some day vertically.
    I am very interested in the progress of this clock.
     
  12. Jim DuBois

    Jim DuBois Registered User
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    #12 Jim DuBois, Dec 25, 2013
    Last edited: Dec 25, 2013
    I trust you refer to the 11 part series on "An Electric Master Clock" by Eliot Isaacs? It may well be the document you refer to from Engineering In Miniature. I don't recollect where I sourced the document from..... It does refer to College Engineering as a source for the castings....but it was published a very long time ago....I see they still show the raw backplate...I will try to order one and see what happens...

    And here is an elliptical bob from an Eli Terry regulator, an interesting and unique clock using gravity impulses etc....
     

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  13. John Robinson

    John Robinson Registered User

    Nov 25, 2013
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    Howdy,
    Yes, that Isaacs article is what I used, mostly, and Hope-Jones "How to build an electric clock" was compared with it when I had questions.

    I've spent most of the day touching the clock, adjusting, learning how and what makes it run. 75 minute run 25dec.jpg pendulum compensator.jpg thermal test.jpg
    First pic is the running clock sitting on the workbench.

    2nd pic is the bob with the compensator I'm using, bob is bored to within 1/2 inch of the top, a quartz tube supports the bob, and a 360 brass tube is the compensator, this is using Robert Matthys scheme with an Invar rod.

    3rd picture is the test bench I built to check thermal expansion of an Invar rod. the heat pad and thermometer is easy to see, the .0001 indicator at the end is not so easy to see. when I get fired up, I'll recheck the unannealed rods I have and post the numbers..

    I just checked the clock and after 2 hours! it was still going well... no clue if it will continue, but I have hopes that the adjustments I have made were what the clock needed to run reliably...

    The telling point I see is that the gathering jewel travel had extended its reach across the count wheel teeth, which tells me that the pendulum is running with power to continue. I have a cheap battery clock for comparison, and the sync is running just a little fast right now.. this is a 1018 steel rod for the pendulum, 52 inches long, and there is roughly a 2 inch total swing left to right at the bottom end.

    I'll be wandering down to the shop every now and then for the rest of the night, checking to see how it is running...

    If tomorrow morning you guys hear a loud WOOOHOOOO , its me ...
     
  14. Jim DuBois

    Jim DuBois Registered User
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    Congratulations on the progress. I got a spec sheet with the Invar I ordered for a regulator project, as follows
     

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  15. John Robinson

    John Robinson Registered User

    Nov 25, 2013
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    Howdy, I'm still playing with the clock today, minor adjustments, I'm now only adjusting ONE thing at a time....ran 6.5 hours then stopped last night.. as usual, I'm impatient....
    here's the British Invar spec sheet of one of the rods I have Invar Alloy 36 - 8.0mm Dia.jpg
     
  16. John Robinson

    John Robinson Registered User

    Nov 25, 2013
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    Howdy,
    Well, the clock has been running for more than 24 hours now, still on the workbench and not really ready for prime time.
    At first, the clock was running about 7 minutes/hour fast before I made a compensator change, now its around 9 seconds/hour fast, although I'm not really setting the clocks' rate, only playing with the clock, as I figure I deserve a little play time after all the work of building it.
    I've made two major adjustments, I replaced the detent roller with a smaller diameter one, that fixed a problem with it occasionally hanging up above the tip of a tooth and stopping the clock, and I replaced the brass temperature compensator tube with a shorter one, as that was easier to do than cutting the quartz tube that is inside the pendulum bob. That change brought the clock time closer to "reality".
    I notice that the pendulum swing length has changed (longer) with the slowing of it, I had not known (or thought of) this would happen. With this longer slower pendulum, I see that the gathering jewel is now reaching left across the tooth closer towards the detent roller, and it seems like the pendulum is adjusted more to the left than the right, so I may have to either adjust the length of the gathering arm, or move pendulum suspension to the right to compensate. I put Dykem marker on the pallet face to see the track of the gravity arm roller, it is straight down the center of the face.
    The gravity arm catch is working very well, I did not install a spring to 'help' it catch the arm spring, and may not need to after all.The clock itself is not very loud when resetting, but the Synchronome slave clock is very klunky and noisy, even with my old man poor hearing...I may investigate bumper installation in the slaves.
    Anyway, I'm pleased with the progress so far...
    thanks and drive carefully
    john robinson
    mechanician
    world land speed record holder Bonneville Salt Flats
    H/GCC dodge colt 144.396 MPH
    1967 BSA Victor 107.371 MPH at Bonneville
    USAShooting Air Pistol National Record holder
    Antarctic Ice Core Driller 3,331.538 meters
    Grandpa
     
  17. Raynerd

    Raynerd Registered User

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  18. John Robinson

    John Robinson Registered User

    Nov 25, 2013
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    Howdy, according to Woodward, the symmetrical slope of the impulse was "a step in the wrong direction". I originally used something similar to raynerd, but am now modifying it with a hand developed architecture to make something similar to the Shortt as shown in the Woodwards' book "My own right time", page 35. I'll post a picture when it is done.
    Right now I've disassembled the clock to paint it, and to do minor and major (the pallet) changes.
    Thanks and drive carefully
    john robinson
     
  19. John Robinson

    John Robinson Registered User

    Nov 25, 2013
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    Howdy, I've begun machining the ball bearing holders for the various pivots on my Synchronome clock. Here's a picture of the holders that thread into the clock back, and one of the bearings sitting on a 1906 Indian head penny, all on the package with bearing dimensions. sync bearing holders 24jan14.jpg .
    I've also ordered firebrick and sundries for building the inert atmosphere heat treat oven I need to anneal the Invar pendulum rods I have. Progress!
     
  20. John Robinson

    John Robinson Registered User

    Nov 25, 2013
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    Howdy, My homebuilt Synchronome is going back together with the new ball bearings. I see that I really need to balance the count wheel, if I flick the count wheel with my finger it free wheels for more than 30 seconds, then does the "here's my heavy side" wave at the end ... this on dry oil free ball bearings...
     
  21. tok-tokkie

    tok-tokkie Registered User

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    On my clock the escape wheel usually reverses slightly when it comes to a stop when it is spun free of the pallets. It does that even after I have counterbalanced it precisely. My shaft also runs in ball bearings. I have got used to it and believe it is some characteristic of ball bearings that they give that little reverse roll after they stop. But having the whole escape assembly in free running bearings makes counterbalancing easy - my clock has a sweep seconds hand so the seconds arbor has a lot of stuff on it.
     
  22. John Robinson

    John Robinson Registered User

    Nov 25, 2013
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    Howdy,
    I've just received permission to both photograph and measure the Shortt #21 impulse mechanism at Yale. It has been in storage since 1963. It is disassembled into major components, and is mostly complete, missing the Shortt Pendulum and various other parts. I plan on going out there in the next month or so.
    johnrobinson
     
  23. John Robinson

    John Robinson Registered User

    Nov 25, 2013
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    1clock case 8apr14.jpg Howdy, I just finished my clock case, I started with an old mahogany box that originally held a Pratt&Whitney supermicrometer. I stripped the finish, applied polyurethane and installed a glass window and brass hinges and clasps and lined the interior with burgundy felt. I'll reinstall my homebuilt Synchronome clock in it in the next few days, and begin gathering Microset data.. johnrobinson
     

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