Pianotech

  • 1.  Agraffe thread size

    Registered Piano Technician
    Posted 09-18-2018 16:52

    Hi gang,

    Looking at getting new agraffes for a 19702 Steinway B.  7/32" or 1/4"?  When did they change over?

    Thanks,



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    Zeno Wood
    Brooklyn, NY
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  • 2.  RE: Agraffe thread size

    Registered Piano Technician
    Posted 09-18-2018 19:41
    Mr. Wood,
    If it's from 1970 they're 1/4". As to when the switch was made I'm not exactly sure but I just put a set in an M from 1935 and they were 1/4" much to my chagrin as I had already bought a 7/32" set.

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    Karl Roeder
    Pompano Beach FL
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  • 3.  RE: Agraffe thread size

    Posted 09-23-2018 03:09
    Steinway changed from the  #12-36 agraffe to the 1/4-36 agraffe in 1929.  All pianos with the new agraffes had a star (*) cast into the plate to indicate the new size. I don't know when the star was discontinued. In all of the Steinway factory literature/notes that I have seen there is no mention of a 7/32"agraffe.  In the change order it specifically says to change the #12-36 agraffe to the 1/4-36 agraffe. This is because in the real world there is no such thing as a 7/32" machine screw or bolt. It is a term/size that we use as piano technicians because as a group we're not that familiar with machining.  FYI- A machine screw is threaded from end to end and is intended to be put in a threaded hole.  A bolt is used with a nut.  Of course nuts can be used with a machine screw so the terms get used interchangeably. Screw sizes range from #0-80 (.060") to #12-28 (.216").  At that point they change to fractional sizes starting at 1/4" and up.  7/32" equals 0.0219" and falls  between #12 and 1/4 ".  You will never find this size in a catalog or hardware store because it doesn't exist (unless you're using a Harbor Freight caliper).  They may say it's a 7/32" but it will be a #12 machine screw.  The "36" is a thread per inch count used for agraffes and I have never seen nor heard of anything else that uses 1/4-36.​​​​​ Some pianos I've seen have had both sizes of agraffes.  Also, don't forget that some agraffes have wide spacing of the string holes and others have narrow.  And since we're on the subject- Why do we buy a 23/32 counter bore (CB) to shave the base of the agraffe?  The 23/32 CB is the smallest CB that has a 1/4 hole in the end.  This hole is for the pilot when it is used as a CB.  But we don't use it that way.  We put the stem of the agraffe into the hole.  Buy a 24/32 which is 3/4 inch.  Then you can use for other things. It's a much more useful size.  Someone should tell the supply houses.  This is piano technology dogma that no one ever thinks about or questions.  I hope this is useful information.

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    Glen Hart
    Grand Junction CO
    970-434-5558
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  • 4.  RE: Agraffe thread size

    Posted 09-23-2018 09:51
    Excellent info...thank you!

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    Jim Ialeggio
    grandpianosolutions.com
    Shirley, MA
    978 425-9026
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  • 5.  RE: Agraffe thread size

    Registered Piano Technician
    Posted 09-23-2018 10:28
    Yes indeed. Thank you for answering questions I wasn't even sure how to ask.
    N. Salmon
    LaVale, MD 21502





  • 6.  RE: Agraffe thread size

    Registered Piano Technician
    Posted 07-05-2019 11:34
    Zeno, 

    I've got a 1906 Steinway B to restring.  What did you run into with the agraffes on yours? 

    Thanks,

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    Greg Graham, RPT
    Brodheadsville, PA
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  • 7.  RE: Agraffe thread size

    Registered Piano Technician
    Posted 07-05-2019 13:26
    I just happened to have replaced an agraffe on a 1903 A - it was a 7/32".  The agraffes on the B I was referring to earlier in this discussion were 1/4", that was a 1960s piano.

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    Zeno Wood
    Brooklyn, NY
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  • 8.  RE: Agraffe thread size

    Registered Piano Technician
    Posted 07-05-2019 13:46
    All,
    Steinway "M" 1952 1/4" agraffe
    Roger