woodworks gear repair project

Discussion in 'Wood Movement Clocks' started by klokwiz, Nov 15, 2011.

  1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.
  1. klokwiz

    klokwiz Registered User
    NAWCC Member

    Feb 4, 2009
    1,231
    35
    48
    WRENCH
    Annapolis, MD
    Country Flag:
    Region Flag:
    hi, just thought i would share my experience repairing my first set of gears on a wooden works clock. This is a boardman and wells clock with new and improved brass bushing wooden works.

    I picked up this technique in Tom Temple's "extreme restoration". I found four gears with broken teeth in the movmt. There were two techniques described in tom's e-book. One is to cut out the tooth and root and glue in a shaped wood block and re-cut new teeth. The second technique was described as a repair for "chipped" teeth. In this repair you use a slow cure (30 minute) two part epoxy mixed with wood filings to make the "new" teeth. In order to create the tooth shapes modeling clay is used to make a form on a section of good teeth on the gear to be repaired.

    to be continued
     
  2. klokwiz

    klokwiz Registered User
    NAWCC Member

    Feb 4, 2009
    1,231
    35
    48
    WRENCH
    Annapolis, MD
    Country Flag:
    Region Flag:
    sorry about two part post.

    so after making the casting of teeth take a file and enlarge the teeth forms slightly so there will be extra space to fill which will be filed or sanded down to correct dimensions (be careful not to remove too much, the epoxy is hard to file down). Now fit the casting over the damaged teeth and use painters edging tape to hold cast to back of gear and form a bottom to the tooth hole. after mixing the wood filings with the epoxy fill the broken teeth making sure you get epoxy all the way to the bottom so you leave no gaps where there should be tooth. After epoxy cures carefully remove casting and file teeth down to correct dimensions. If you rough up the front of the epoxy to get rid of shine the "tooth" blends in nicely. Note: it helps to use like colored wood to get good color match, also the clay is a self harding type which doesn't require firing in oven.

    I have found the teeth are stronger than original and nearly blend in to the gear. Since it does not remove any of the original gear I think this is a great way of restoring without altering the orininal component.

    The last two photos are of a more traditional repair to the drive gear for the count wheel. Here I glued four new teeth made of wood and then shaped them to the correct size.

    thanks for reading, I'll be glad to explain any information not included.

    Joe Hall
     

    Attached Files:

  3. emhitch

    emhitch Registered User
    NAWCC Member

    Mar 17, 2009
    97
    1
    8
    medical device design engineer
    pittsburgh, pa
    Country Flag:
    Region Flag:
    Hi Joe, I'm having more and more requests for wooden movement restoration and I am very interested in Tom Temple's technique you have so very comprehensively described. Can you tell me the specific self hardening clay and two part epoxy you are using (manufacturer, trade name, grade, etc.)? Also, what type of wood have you used for the "filings"? I want to exactly duplicate your process and materials since you obviously have had very durable and aesthetically pleasing results. Mark
     
  4. John Teeter

    John Teeter Registered User
    NAWCC Fellow NAWCC Member Golden Circle

    Jan 31, 2001
    56
    1
    0
    Joe, Good Job! I have found Tom Temple's E-book to be very helpful. I especially like like the fact that he emphasizes conservative restoration processes. Check it out at http://www.xrestore.com
    John
     
  5. klokwiz

    klokwiz Registered User
    NAWCC Member

    Feb 4, 2009
    1,231
    35
    48
    WRENCH
    Annapolis, MD
    Country Flag:
    Region Flag:
    #5 klokwiz, Nov 21, 2011
    Last edited: Nov 21, 2011
    John, thank you! And the conservation aspect appeals to me as well.

    Mark, I picked up the clay at a Micheal's craft store. It is a german product. I don't have name with me. The important part is it sets hard without having to fire it in a kiln. You can probably use most any brand. If you wish the exact name i will get it.

    One aspect was that some of the clay will be stuck to the epoxy after the mould is removed. You will want to have enough "tooth" so you can remove the clay for appearance.

    Again I will need to check epoxy name but it came from a local hobby store. They apparently sell several types, they differ by the time it takes to set (or working time) the one i used is 30 minute type, this was plenty of time to fill teeth. They say allow to set 24 hours, but I was able to remove mould much earlier.

    It is recommended to use a Hard wood, but since it is in a hard epoxy I'm not sure it matters greatly. I used an old piece of Mahogony scrap which had a dark finish like the gears i was working on. So I think if you choose the wood based on color match it should work well.

    Glad to hear you are getting these old guys working again, I love to listen to them "groaning". Let me know how your repairs turn out. let me know if youhave more questions...

    Joe.
     
  6. emhitch

    emhitch Registered User
    NAWCC Member

    Mar 17, 2009
    97
    1
    8
    medical device design engineer
    pittsburgh, pa
    Country Flag:
    Region Flag:
    Hi Joe,
    Thanks for your reply. I see that Michael's has a line of molding clay from Germany called Fimo made by Staedtler. My only concern is that according to the website information, the 3 Fimo clays they offer must be cured at ~230F for 30 minutes (and the clay you used does not require any curing). If it is not too much trouble for you, could you confirm the clay you have used? Regarding the epoxy, I'm sure I can find one with a longer pot life (~30 minutes) at my local hardware store. And thanks for the tip on the mahogany, I'll use it.
    Thanks again!
    Mark
     
  7. glenhead

    glenhead Registered User
    NAWCC Member

    Nov 15, 2009
    1,027
    88
    48
    Telecom Engineer
    Williamson County, Texas
    Country Flag:
    Region Flag:
    On the subject of epoxies...

    As you found, there are several different working times available for epoxies. I used to build remote-control airplanes, and experimented with many epoxies for gluing and molding. The working times shown (five, fifteen, and thirty minute, plus two hours are the most common) are usually a bit long; don't be surprised to have five-minute epoxy pretty much unworkable three minutes after mixing.

    Shorter working means faster final cure (obviously). Fast cure means more brittle, and if the repair is subjected to repeated stresses there's a higher possibility of the epoxy crumbling over time. It also means less resistance to heat and moisture over the long run. Faster epoxies tend to yellow more than slower. Finally, faster cure means more heat - curing is a chemical reaction, and five-minute epoxy gets danged hot while it's setting. If you're mixing in colors or fillers (as Joe mentioned, sawdust does a decent job for sort-of matching color), the five-minute stuff is pretty much guaranteed to solidify before you can do anything with it. Thirty minute will work if you're quick at mixing and applying or molding. It's far more flexible and resilient than five minute, and should last forever as a molded clock tooth. Two hour is really nice stuff to work with if you're blending in additives - plenty of mess-with time without the hurry-up aspect. Be sure you pay attention to the ratio of the two parts of any epoxy - too much resin and the epoxy will stay sticky, too much hardener and you lose strength.

    The final cure time listed on the bottle is the time needed for the chemical reaction to pretty well run itself out. As Joe discovered, you can remove a mold quite a while before the "final" cure. I always just poke the molded epoxy with a fingernail to see if it's hard.

    Hope this helps someone.

    Glen
     
  8. harold bain

    harold bain Registered User
    NAWCC Member Deceased

    Nov 4, 2002
    40,850
    140
    63
    Male
    deceased
    Whitby, Ontario, Canada
    Country Flag:
    Region Flag:
    Great advice about the different work times for epoxy, Glen. It's getting harder to find the 2 part epoxies in separate tubes any more. I think Lepage may have discontinued making them this way. The stuff I have is "Regular epoxy # 11" , which sets in 90 minutes and needs 24 hours for a full cure. It has a chart with what each of the other epoxies are best for bonding. #12 is the 5 minute version. But, I haven't seen these for sale in my local hardware stores in quite a few years.
     
  9. klokwiz

    klokwiz Registered User
    NAWCC Member

    Feb 4, 2009
    1,231
    35
    48
    WRENCH
    Annapolis, MD
    Country Flag:
    Region Flag:
    mark, here are photos of the clay i used. very little english on label, purchased at michaels crafts. as i mantioned before it does not require firing to harden. joe.
     

    Attached Files:

  10. emhitch

    emhitch Registered User
    NAWCC Member

    Mar 17, 2009
    97
    1
    8
    medical device design engineer
    pittsburgh, pa
    Country Flag:
    Region Flag:
    Joe,
    Thank you for posting this information. Michael's does not show this clay on their website so hopefully I can find it in the store. I appreciate your guidance.
    Mark
     
  11. klokwiz

    klokwiz Registered User
    NAWCC Member

    Feb 4, 2009
    1,231
    35
    48
    WRENCH
    Annapolis, MD
    Country Flag:
    Region Flag:
    mark, I know they don't tried to find it for you yesterday. I think the store here just bought this brand one time. I would ask the store for the non firing clay. I have a bunch left could mail you some if you get stuck. Joe.
     
  12. Jon Lester

    Jon Lester Registered User
    NAWCC Member

    May 10, 2011
    34
    2
    8
    engineer
    Ohio
    Country Flag:
    Region Flag:
    I have had success using these components for wooden tooth repair. You can find the clay and pigment using Google search. The epoxy is available at most hardware stores.
     

    Attached Files:

Share This Page