Shim Thickness Planner

What this tool is for

Compare tapered thickness differences for a full pocket and an entered shorter shim length. 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

Enter desired angular comparison, actual shim length, full pocket length, and one unit. Confirm which end is thick and whether the proposed shim supports the intended area.

• 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

Desired neck-angle change (degrees)

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

Entered shim length

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

Neck pocket length

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

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

Check angle sign, thick-end orientation, bridge travel, and neck projection with a reversible mock-up. Re-measure after strings reach pitch.

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

Thickness difference is length×tan(angle). The tool reports both entered-shim and full-pocket taper so a short strip is not mistaken for a full-contact wedge.

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 1-degree change across 60 mm produces about 1.047 mm thickness difference; across a 76.2 mm pocket it is about 1.330 mm. Those are geometric comparisons, not prescriptions.

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

Material compression, pocket fit, screw load, finish, joint design, and structural contact are not modeled. Avoid improvised point loads or permanent cutting without qualified assessment.

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

• Neck Angle Planner — Model neck-plane projection to a measured bridge height without authorizing structural cutting.
• High Action Diagnostic Tool — Separate relief, bridge, nut, and neck-angle clues before adjustment.
• Geometry Measurement Definitions — Name every datum before entering a number.

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