Headstock String Break-Angle Tool

What this tool is for

Compare nut-to-post and optional string-tree break angles from measured rise and run. Geometry tools apply explicit models to named measurements. A coordinate or angle must still be checked against a physical drawing, real hardware, tolerances, and material behavior.

Use it when you can describe the current state and need a defensible next check. It is not a shortcut around inspection: preserve the starting state, change one variable, and verify the result under the same conditions.

Before you begin

Measure horizontal run from nut witness point to post or tree and perpendicular height difference from the same string plane. Observe actual string contact and winding direction.

• Use a stable, tuned instrument unless the page specifically investigates tuning.
• Name the physical reference, unit, and test condition beside every important number.
• Keep the original measurements so any reversible change can be returned to baseline.

Input guide

Nut witness point to tuner post

provides a measured or counted input; confirm the allowed range and repeat the reading before relying on it.

Post height below nut string plane

supplies a measured geometric quantity whose datum and resolution should be written down.

Nut to string tree distance

supplies a measured geometric quantity whose datum and resolution should be written down.

String tree height below nut plane

supplies a measured geometric quantity whose datum and resolution should be written down.

Headstock type

classifies an observed condition; choose “unknown” or “not tested” instead of guessing when available.

Input and display unit

sets the interpretation and display unit; do not mix units elsewhere in the same run.

Input labels describe evidence, not targets. A placeholder demonstrates format only; it is never a recommendation for a particular guitar.

How the result should be read

Compare strings and look for enough stable witness-point contact without excessive friction. Use tuning behavior and manufacturer geometry alongside the number.

Read priorities from top to bottom, but stop as soon as new evidence contradicts an earlier assumption. Save or print the result ticket with the entered conditions so another person can reproduce the decision.

Method and logic

Break angle is atan(height difference/run). Optional tree geometry is calculated independently so the two contact paths are not confused.

The page keeps calculation and diagnostic claims deliberately bounded. Display rounding improves readability, while the underlying logic uses entered values; descriptive branches report relative tendencies and the evidence needed to confirm them.

Worked example

A 10 mm drop over an 80 mm run gives about 7.1 degrees. A string tree closer to the nut can create a larger angle from a smaller drop.

The example demonstrates reasoning, not a universal setup specification. Substitute real measurements and repeat the final test before accepting the next action.

Assumptions and limitations

Post diameter, wrap stack, nut slot shape, tree friction, headstock flex, and three-dimensional lateral path are outside the side-view triangle. No universal ideal angle is asserted.

Instrument design, service history, measurement error, and player technique can outweigh a calculator or checklist. Where manufacturer instructions exist for the exact hardware, use those instructions and record the revision consulted.

Safety and stop conditions

Stop for abnormal resistance, cracking, heat, odor, electrical sensation, moving wood or joints, a measurement that cannot be repeated, or any step that would remove material without a confirmed cause. Secure strings and stored mechanical energy before hardware work. Refer structural, fret-cutting, mains-powered, or uncertain repairs to a qualified technician.

Related workflow

• Tuning Stability Troubleshooter — Trace tuning drift through strings, nut, hardware, tremolo, and environment.
• Geometry Measurement Definitions — Name every datum before entering a number.
• Guitar Setup Measurement Points — Use repeatable setup datums.

Open the related page that answers the next unresolved question; do not run every tool as if every system needs adjustment.