Making A Gong 101

Discussion in 'Clock Repair' started by chimeclockfan, Oct 13, 2019.

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  1. chimeclockfan

    chimeclockfan Registered User
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    (If it is possible to move this all to the Encyclopedia or tips section, please do so.)

    For the past 7 years I have tuned over 20 different gong rods ("chime rods") sets, all to replicate original sets which were damaged beyond repair. Salvageable gong sets were also repaired during this time.
    These are some passing tips for other repairers who will eventually be required to fabricate new rod sets when seeking spares and repairing damaged rods simply aren't feasible. Photos of the entire procedures are not available right now so I have simply attached some examples of completed gongs instead.

    A gong is a wire fixed to a pedestal which resonates when struck. The wire may be spiral ("Coil") or straight ("Rod") in shape. The wire is either staked into the pedestal or fixed into a retainer fitting which is then mounted onto the pedestal. A simple coil wire not fixed to any pedestal was traditionally known as a 'tonfeder' and is not to be mistaken with more developed gongs.

    "Making Coiled Gongs"

    The majority of this information was sourced from a clock repairer's book written by Bernard Edward Jones.

    While gongs are best bought ready-made, this simply isn't always what will work out and a repairer is expected to make suitable gongs. Steel wire is first brazed into a brass end block fitting, then coiled into a spiral. The wire is then heated to a bright red hue, evenly all over and hardened. Now it is polished then blued.

    Round wire is easiest to make but also gives a non-harmonic sound. Most suitable for striking gongs. Typical wire should be 3/16 inches thick and at least 45 inches long - if a bigger gong is required, longer wire is needed. The brass block fitting should be 1 1/4 inch by 5/8 inch and 3/8 inch, to which the wire is brazed into, ensuring it is completely tight. After brazing, coil the wire into a spiral of at least 3 turns and 7 inches outside diameter. The exact specifications vary depending on which size of gong you are making. To harden the steel wire coil, heat it in a forge fire and plunge in water, then polish with emery. Then it must be blued.

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    Clocks that chime Westminster and other melodies require flat-wire or square-wire for each tuned note. This is also required for striking gongs where a round wire is not desired. The procedure for crafting tuned coils is very much as described above except with flat wire and being sure to cut different sizes of wire for each note required. Additionally, the attached point of the coil wire must be tapered slightly before coiling. The coil diameter should be relative to each note - smaller coil for higher notes, larger coil for lower notes. To determine each note it is advised to use a recording of a similar clock for further guidance.

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    "Tuning Rod Gongs"

    While I did the brunt of hands-on work myself, the late Hans Heinrich-Schmid must be credited for helping with my research.

    Rod gongs have been manufactured in tuned and un-tuned sets for some time now and only ceased a couple years back when the primary supplier - Haller & Co., Germany - went out of business. While efforts are under-way to produce suitable rods again from parts suppliers, untuned must be tuned to accommodate gongs that do not use the typical sets used by modern clock companies. Rods are trimmed to exact length for each note required, being sure not to trim any rod too short or else it will not be feasible to lower its pitch effectively. This alone is all many rods require besides fitting them into their pedestal block.

    While the rods must be adjusted away from one-another after installing into their pedestal block, it is not required that they are entirely in-line with one another. Just enough so they don't run into each other or anything else inside the case. The rods must also not be bent beyond tuning. Too many bends = rod eventually fractures.

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    Some rods require further attention in the form of notching and filing, common tricks among the German gong manufacturing trade to enhance the rod gong's sound. The tapered neck may be notched with a mill file, creating a small but prominent flat section along the taper. It is important not to file down too much of the neck to avoid issues with sound quality - it is a very meticulous task that was traditionally left up to a specialized trade. In fact many gongs were not completed by the clock factories but rather gong manufacturing facilities who sold their products exclusively to clock factories. When the rods are cut to length one will find the cut end is rough and jagged. It may be filed down smooth with a mill file, which also gives the completed rod a clearer sound compared to one which has not been smoothed.

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    Rods are not always tuned to the average musical standard and varied considerately in regards to how they were really tuned. It is always easiest to tune gongs "by ear", going by a recording of a good gong set to use as an audio guide. While I cannot upload it right here, I retain a massive HQ sound archive of different coil & rod gong sets that will be helpful for anyone trying to tune gongs. I am eager to have this uploaded to the NAWCC rather than an outside source such as YouTube at some point to help other repairers. In the meantime, please consult through private e-mail.

    "Cleaning Gongs"

    The rods and coils are also light layered with a film of oil. Sometimes this may give out due to excess heat exposure. Rods and coils benefit from being re-layered with oil which not only improves sound quality but also gives some resistance to corrosion for air exposure. I use "Slick Lube", sprayed onto a rag then gently wiped all around. It is easy enough to spritz some lube into the holes where the gong rods emerge from so the tapered necks are also cleaned - removing the rods or coils is never advised unless you are replacing them with a new set. Sanding down the rods with sandpaper is not advised as this will negatively impact the finer tuning.

    If the pedestal block has any painting to do, it is to be coated with enamel paint. Thin paint gives the gong a louder sound - thicker paint, quieter. Fine detailing must be applied with brushes or toothpicks.

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    It may be required to mix rods of different metal alloys to create the desired sound. Kienzle notably did this, incorporating 1 brass rod and 3 steel rods to give a mellower chord. Other clocks have two brass rods for the hour strike and 4 rods for the Westminster chime. Sometimes just the one rod is a different alloy, sometimes the entire set.

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    Dave T and Bruce Alexander like this.
  2. shutterbug

    shutterbug Moderator
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    Justin, I would like to change the title of this great tutorial to :Making A Gong 101 if you approve. It will make it easier to find in a search. Then maybe bangster will add it to tutorial sticky at the top of the forum. OK with you?
     
    PatH likes this.
  3. chimeclockfan

    chimeclockfan Registered User
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    Sounds good to me. :o:)
     
  4. shutterbug

    shutterbug Moderator
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  5. tom427cid

    tom427cid Registered User
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    Thank you for a most informative tutorial.
    tom
     
  6. bangster

    bangster Moderator
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    I had the same idea. :)
     

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