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Distance from the heel to the bridge?

Discussion in 'Luthier's Corner' started by Luke Sheridan, Jan 4, 2005.


  1. Luke Sheridan

    Luke Sheridan Commercial User

    Dec 30, 2004
    Yonkers, NY
    I build guitars and sell them. Strings, too
    I'm in the process of building a 5-string and was wondering if there is an optimal length between the heel and the bridge. I'm modeling it after a Thumb Bolt-on and my traces that I scaled up in Illustrator reveal that without extending the heel 4-5 inches past the lower horn, I'll never get a 34 scale. Perhaps I'm missing something obvious.
     
  2. The obvious thing you are missing is that the heel has absolutely no bearing on bridge location. The real measurement you should concentrate on is the distance from the 12th fret to the bridge saddles. The amount the heel of the neck extends into the body covers 2 things - the number of frets and to make room for the screws. If you had the neck/bridge spacing set up perfectly and you removed a fret, would that change the location of the bridge. No, that would only open up more space between the heel and the bridge. What I'm getting at here is a "scale" length (34", 35" whatever) is measured from the nut to the saddles and the 12th fret is exactly halfway between the two no matter how many frets the neck has. THAT'S your critical measurement.

    So, if you're looking to balance a body design by locating the upper horn near the 12th fret, you should then measure from the 12th fret ½ your scale lenght to find the general location of your bridge. If you move your neck up or back, the bridge must move the same amount.
     
  3. Luke, I remember something you mentioned from the other thread about getting a full size pattern. Did you scale your photo up so that the measurement between the nut and the 12th fret was ½ the scale length? As I recall, you stated that you scaled the art to 12" wide at the body. That tells me that there wasn't a reference to the scale used for the enlargement.

    If you have done all of this correctly and you still have what you think is too much neck overlapping the body area, there are two things I know you can do. First is lose a couple of frets. I personally don't think 2 octave necks are much use 99% of the time. The second thing is to lengthen your body a little. Or maybe a blend of the two will get you what you want.
     
  4. Luke Sheridan

    Luke Sheridan Commercial User

    Dec 30, 2004
    Yonkers, NY
    I build guitars and sell them. Strings, too
    I only traced the body so no scale wasn't taken into account. The length of the upper horn is 17 inches and the height in 11.75. I was able to do a quick measurement of a Thumb in a store. That told me the width and height are correct. Their heel was at approx 14 inches. My heel area has 16 inches of meat.

    I'm using only 21.

    Well the body is cut, including the outer perimeter of the horns. The heel area is still squared off at 16 inches so I can play with that. I guess I can taper the rear of the heel and possibly the neck once I receive it. Can the heel of a Warmoth P neck be screwed in without using the standard hole spacing? I could bolt closer to the 21st fret and about the 18th to avoid having too much heel length in the body of the bass. I know, I shoulda had these parts on hand before I started cutting. But regardless, you still provided me some valuable info that I can use as I progress. I'll be posting in-progress pics over the course of this project.
     
  5. The Warmoths don't come with any holes drilled so you can put 'em where you need 'em. The TR nut on the Warmoths is also pretty slim so I don't think you'll have any clearance problems there.

    You've discovered something all new builders should know - do full size mockups or scale drawings of the entire intrument. If there's something about basses and their shapes that I've learned it's that the shapes are VERY deceiving. Without mathematic confirmation that things fit, my eye (at least) gets fooled regularly that things are correct - especially issues involving scale lengths.

    Sounds like your on the right path now though.