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Double drilling of pinblock

  • 1.  Double drilling of pinblock

    Posted 01-18-2019 20:16
    Dud my first "double drilled" block today. I kind of like it. Also did it without the plate in (as was suggested on some other thread). Also 👍👍 on that. Can't figure out why I didn't think of that before.

    Only one minor problem was in getting the final drill bit to line up perfectly centered on the initial bore, producing some variation in hole location relative to plate hole. Nothing severe, but I think next time I will favor center punching the hole slightly more towards the back of the hole than I did this time (almost perfectly centered this time). Slight tendency to skate toward the front of the hole in drilling.

    All in all I'm quite satisfied with the results.

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
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  • 2.  RE: Double drilling of pinblock

    Posted 01-19-2019 01:02
    Peter,
    Use a reamer instead of a drill bit for your second cut and you will find that centering is not a problem. Chucking reamers with their long shanks follow the hole more precisely. Also, there are about 10 times more sizes in reamers than drill bits.
    Roger





  • 3.  RE: Double drilling of pinblock

    Posted 01-19-2019 12:50
    Roger,

    Do you mean using the reamer in the drill press or hand reaming a nearly sized hole to final size?

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
    ------------------------------



  • 4.  RE: Double drilling of pinblock

    Posted 01-19-2019 14:42
    Peter,
    Ream with the drill press. Keep reaming to a minimum – about .010" larger that the drill size. I keep all sizes of reamers suitable for the #2 tuning pin then choose the proper reamer for the pinblock material in use. I'm sure we all establish these parameters with a piece of scrap material. Basically the reamer removes the polished edges made by the drill bit. One benefit of the vast size of reamers is that you can change for a slightly smaller hole needed in the bass section. Also, be mindful of you speed – about 500 rpm.
    Roger





  • 5.  RE: Double drilling of pinblock

    Posted 01-20-2019 10:53
    Just finished a double drilled block yesterday.  Didn't have that problem with centering.  The important one is the first hole.  Use a centering punch like this to mark the hole through the plate.  If you use one that is just slightly smaller than the plate hole you can pull it to the back edge and move the mark just back of center if you prefer.  Then drill the first pass with a brad point drill which allows you to hit the punch target very precisely I use a 7/32" drill for the first pass.  Just touch the mark with the brad point before you run her through matey.  The second pass ends up being a very gentle reaming and the drill will tend to want to self center.  Good light and setting the drill up so it is just marginally above the block when drilling will make it easier to visually align.



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    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
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  • 6.  RE: Double drilling of pinblock

    Posted 01-20-2019 15:18
    I don't double dip my frito lays, but I do double drill pinblocks. I prefer out of the piano drilling on my mill. My second pass uses a drill bit that tapers to a point. I keep the block so it freely moves side to side but can't lift up (very important). Then the drill bit perfectly centers the hole itself.





  • 7.  RE: Double drilling of pinblock

    Posted 01-20-2019 15:58
    Why would you use a tapered bit for the second pass?  Wouldn't that make the pin tightest at the bottom of the hole?  That's not preferable in my opinion.

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    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------



  • 8.  RE: Double drilling of pinblock

    Posted 01-20-2019 17:50
      |   view attached
    Apologize, I don't know the name of these. 2 flutes with pointed tips.





  • 9.  RE: Double drilling of pinblock

    Posted 01-20-2019 18:16
    David,

    I do/did all those things. Lighting was definitely part of it. Had good lighting from both sides, however shadowing still seemed to make it slightly off sometimes. I think the pointier drill may have helped. I'll need to experiment on scrap with the reamer to see if I can manage that too.

    None are unacceptable. 95% great. 5% not perfect.  I'm happy, but obviously room for improvement.

    Pwg

    ------------------------------
    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
    ------------------------------



  • 10.  RE: Double drilling of pinblock

    Posted 01-20-2019 19:07
    I'd be good with that.  First pass is the most critical on hitting the mark.  Second pass takes me about 1/2 the time.

    ------------------------------
    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------



  • 11.  RE: Double drilling of pinblock

    Posted 01-20-2019 19:17
    thumbnail image

    I see, ok.  That's not tapered.  This is tapered.  You don't want to use that for a pinblock.

    ------------------------------
    David Love RPT
    www.davidlovepianos.com
    davidlovepianos@comcast.net
    415 407 8320
    ------------------------------



  • 12.  RE: Double drilling of pinblock

    Posted 01-21-2019 17:40
    I can see that with a little practice it can be quite productive (and accurate) .

    Is that the type of reamer suggested (except straight)?  I would need something about 7"-8" long to accommodate my on board drilling rig.

    Pwg

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    Peter Grey
    Stratham NH
    603-686-2395
    pianodoctor57@gmail.com
    ------------------------------