Pianotech

  • 1.  Drilling new bridge cap

    Registered Piano Technician
    Posted 07-04-2022 14:47
    I am getting ready to drill the new bridge cap on a Steinway D. This is nothing new to me and I usually drill by hand. I was wondering if and what anyone else uses a jig for setting depth and angle. I have used the ones typically sold by Rockler and Woodcraft, but find them a bit cumbersome and difficult stabilize. TIA

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    Dave Conte

    University of Tennessee
    Knoxville TN
    (817) 307-5656
    Owner: Rocky Top Piano
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  • 2.  RE: Drilling new bridge cap

    Posted 07-05-2022 10:41
    I use a drill bit collet and eye ball which is surprisingly "accurate" with practice. I'm currently making a counterbalancing arm myself for the purpose. But if the purpose is to eliminate false beat potential the cap material becomes important.. Don't use maple or beech for caps as their Janka hardness is only 1400psi. Laminated caps I just don't like the sound, but to each his own. Jeffries has some nice species to choose from at the moment, their black wenge is incredibly hard. I took all their quartersawn osage orange, sorry kinda not really.
    -chris



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  • 3.  RE: Drilling new bridge cap

    Registered Piano Technician
    Posted 07-06-2022 05:38


    Chris said "don't use maple or beech for caps." Does a Hard Maple cap really cause false beats, and a harder substance eliminate the false beats? More supporting evidence please. Harder material bridge caps present a multitude of practical challenges, some that may contribute to false beats. Furthermore, one could easily make the case that a Hard Maple bridge cap is amplifying other imperfections that are causing false beats. A harder cap will simply do that even "better." And while a solid Wenge bridge cap might prevent naughty technicians from damaging bridge caps, it will also come with its disadvantages! Based on my own experiences and education, I see other more glaring points of vulnerability in the stringing system where false beats are more likely to arise.

    As far as Osage Orange and Wenge.
    Osage Orange is "barking up the right tree" (pun) but unproven compared to Hard Maple and Beech. Here's why. Denser woods tend to be less dimensionally-stable than less-dense woods. Osage is harder than Hard Maple 2,600:1,400. However, Osage Orange is reportedly still good on dimensional stability given its density. Even so, I find the higher density to be a liability in terms of reliability and longevity and not the other way around. This coming from the woodworking side of things.

    Wenge on the other hand has serious practical issues such as dulling tools and causing painful infected splinters to anyone having to work the wood - definitely during bridge work as a specialty I'm experienced with. It's a heightened hazard to breath the dust as well. It also has porosity, which I don't want for acoustic reasons. And then, what is the proven record of this material compared with Hard Maple? Again, even a seasoned bridge expert is going to be in for a shock if attempting to use Wenge for a bridge cap!

    Pianos are interesting creatures unlike most things made today. The piano can easily suffer from too much improvement.

    For this type of Forum, I'm always going to favor hard-hitting evidence and science over more casual anecdotal advice. Casual advice is also fine if understood by all to be only that. I'm not a scientist or educated engineer but I do try to approach my work with a scientific approach as much as is possible and practical.
    Thanks!



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    Tom Wright, RPT
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  • 4.  RE: Drilling new bridge cap

    Posted 07-06-2022 13:41
    Tom,
    Often the mental reasoning exercise is refuted by the actual doing.

    One could easily argue Maple has a horrible track record upon close inspection.
    You stated " Even so, I find the higher density to be a liability in terms of reliability and longevity and not the other way around."
    You may not be aware of this Tom, but many fine pianos actually have used Boxwood (Janka 2800psi) for the Caps for who knows how long -at least  century i'd guess? And i cant even remember out of the last 50 pianos with boxwood caps i've seen , that they didn't remain  in great condition, certainly won't see the stress cracks like you do with maple.
    The choice of Maple was most likely a cost effective concern rather than a performance one. Maple was/is local and easy to get, boxwood comes from other parts of the world.   When i compare the tone of maple to the harder woods, I would describe it as muddy, on the other hand Maclura Pomifera sounds beautiful and transparent.  But if the status quo is fine, it makes absolutely no bit of difference.

    -chris



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    Chernobieff Piano Restorations
    "Where Tone is Key, and Mammoths are not extinct."
    865-986-7720 (text only please)
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  • 5.  RE: Drilling new bridge cap

    Registered Piano Technician
    Posted 07-06-2022 15:54
    I agree with "Often the mental reasoning exercise is refuted by the actual doing." I'm not present on this forum much.


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    Tom Wright, RPT
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    Original Message


  • 6.  RE: Drilling new bridge cap

    Posted 07-06-2022 06:21
    I use a Dremel tool with a drill bit installed. A simple piece of masking tape to mark the depth. I use a little angle gauge for the first couple, then the muscle memory takes over.


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  • 7.  RE: Drilling new bridge cap

    Registered Piano Technician
    Posted 07-06-2022 08:16
    Thanks for all the responses so far. There is no false beat issue that I can determine that does not actually result from the original failures, which is what I am rectifying with the new cap.
    Maple is fine. I got it from Bolduc which is the OEM for Steinway. No need to reinvent, but thanks for the ponder fodder. 

    Phil, did you start doing this after the Petrof factory tour?

    I had been using a plexiglass (acrylic) shield at the thickness to let the drill jaws touch so the depth was uniform, and setting the angle against a corresponding block on the first few until repetition memory set in.
    But the acrylic got opaque quickly so I had to make up numerous sets. It did protect the bridge and kept the depth uniform, but it turned out to be a hassle to keep steady and frequently replace. 






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  • 8.  RE: Drilling new bridge cap

    Registered Piano Technician
    Posted 07-06-2022 02:12
      |   view attached

    For drilling stops I've used a drilled out small wood dowel tapered and glued to the drill bit with CA, or simply blue masking tape wrapped around the bit. The latter is springy but can work well. But if there are voids or loose pegs in the bridge trunk, bad things happen. If everything down there is as solid as can be, drilling depth becomes easier. To make the little wooden collet, use a drill press and the actual size bit if you can. Super easy if you have the woodworking skills and equipment to do this level of work.

    Metal collets can distort small bits due to the set screw pressure but can alternatively be glued in place and also tapered for the angled drilling. Otherwise they make a nasty dig in the bridge cap when they bottom out. But this is a tricky way to proceed because drill bits get dull and collets cost money and its annoying to glue them to drill bits. Although you could use CA glue and debonder. For these reasons the custom made wooden drill stop is the elegant solution, in my humble opinion. The other challenge with drill bit stops attached to the actual bit is that the wood shavings and chips from the drilling process need a smooth exit or they tend to interfere with good drilling tolerances - when it comes to the fit of the bridge pins. There are workarounds for this issue too. For example, you can carve flute extensions out if you're using the wooden dowel type stop. You can also drill a hole in 2 or 3 insertions and retractions of the drill bit to allow for better chip extraction. Proceed with care to maintain hole tolerances...

    For angle, I made a sighting reference tool using a block of wood with a hole drilled at the desired angle and a dowel about 8-10" long placed into it. This is placed in my sightline or as close as possible as a visual reference while working. I've done freehand with an electric drill mostly since I'm likely to drill and notch the bridge after its glued to the soundboard.

    Another tip is fine-adjustment of drill bit tolerances for bit-to-pin tolerances. Particularly in the smaller pin and bit sizes #7 and # 6. sand the side of the drill bit on a fine block by offering the sanding block to the side of the drill bit while it is spinning in a hand drill or drill press. Very useful and effective option when needed.

    I also favor bridge pins left stock rather than filed down. Attached is a 2019 photo of my work where I accepted inconsistencies in pin height but achieved good tone in the treble with a Bolduc board that I also built up in my shop. I do try hard to get consistent hole depth though and the wood stop will be the more positive one. And when dealing with original trunks, however well pegged and glued, some pins seat firmly farther down than others.




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    Tom Wright, RPT
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