Calculating the guitar’s neck angle

I awoke to find it raining heavily and, according to the forecast, it is here for rest of the day. No routing for me today. I’ve used the time to review and add more detail into my plans.

Now that I’ve got the wraparound bridge I can work on calculating the neck angle.

I want the bottom edge of the end of the fretboard to sit flat on the top (there is a short overhang past the end of the neck). The height of the bridge, at its very lowest, is 19mm. The fretboard (incl frets) is 7mm thick. The end of the fretboard is 168mm from the bridge saddles. This means that the neck inclination needs to be a drop of 12mm over 168mm distance which. Reaching back into the dusty recesses of my maths degree (who knew that it would ever come in useful, eh?) this equates to very close to 4 degrees.

If you’re interested the calculation is Angle = ArcSin (height/distance) = ArcSin (12/168) = ArcSin (0.07143) = 4.09604 degrees. I used this online calculator.

Here’s a diagram of what I mean;

Of course with that geometry it would mean the strings were far too low, but I reasoned that this is the very lowest that the bridge would ever need to go.

And just to help me visualise the angle, I tried this;

The matchsticks lift the bridge of the body the same distance as the bridge studs. And yes I know it is worthy of “thereifixedit“, but it works for me.

Update: After an email from the ever helpful and insightful Steve Benford, of Benford Guitars, I realised that I’d measured the thickness of the fretboard at the edge and not the centre! This was a small but significant error. The drop should actually be 9mm over the 168mm distance from bridge to fretboard. This is 3 degrees and not the 4 from my original calculation.

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2 thoughts on “Calculating the guitar’s neck angle

  1. I wish I had read this before I bought a “badass” style bridge for a PRS style guitar I made. I had to buy a new bridge and make mods to get it in good playing order.

  2. Hi, great blog, but:
    for little angle it’s possible to confuse arcsin with arctan, but the real calculation is arctan(height/distance), isn’t it?

    Bye,
    Enzo
    vpgguitars.com

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