How to measure bore size

Discussion in 'Trumpet Discussion' started by Blind Bruce, Jul 12, 2009.

  1. Blind Bruce

    Blind Bruce Pianissimo User

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    I always thought that bore size was the internal diameter of the lead pipe. Now a very reliable source says that it is the internal diameter of the second valve slide. Which is true?:-?
     
  2. nordlandstrompet

    nordlandstrompet Forte User

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    Your very reliable source is very reliable :thumbsup:
     
  3. geobe

    geobe New Friend

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    Apr 25, 2009
    The leadpipe changes diameter along its length. The bore size is measured at the second valve slide.
     
  4. oldlou

    oldlou Forte User

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    To be just a wee bit more precise, the bore size is measured at the I.D.,( inner diameter ), of the second valve crook, not at the extensions of the second valve slide, which are those pieces of tubing soldered to the second valve casing.



    OLDLOU>>
     
  5. Blind Bruce

    Blind Bruce Pianissimo User

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    Oldlou, you anticipated my next question but confused me by referring to the crook.
    Is that the piece that we can remove or the part that is soldered to the second valve casing?
     
  6. oldlou

    oldlou Forte User

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    The 'crook' is that removable 'C' shaped thingy.


    OLDLOU>>
     
  7. Puukka

    Puukka Pianissimo User

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    Some weeks ago I wondered the same.
    I have a 460" bore Burbank 5X and a 464" bore Burbank 3X+.
    Recently I tried to interchange all four valve slides, expecting, that they won´t be interchangeable.
    Interestingly they were without any problem, so I wonder, where I can measure the difference?
    Herbert
     
  8. Brekelefuw

    Brekelefuw Fortissimo User

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    The difference in the slides is in the length, not bore size. Those stay consistant because the trumpet tapers at only two parts of the horn; the leadpipe and the bell. The rest is cylindrical.
     
  9. Blind Bruce

    Blind Bruce Pianissimo User

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    OK, I got the crook, and I tried to measure the ID with my vernier calipers. Not too consistant readings!!
    What is generally used to measure accurately?
     
  10. Brekelefuw

    Brekelefuw Fortissimo User

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    I have used two kinds of calipers. Normal digital calipers, as well as special calipers meant for measuring the ID of tubes. The special ones look like a gun with a rod on the end that expands when you pull the trigger. Very expensive, and very cool.
     

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