Pot shafts too short for my semi-hollow body. How do I fix it?
When you build a semi-hollow guitar kit, there is a small chance you run into this: you go to install the volume and tone potentiometers, and the pot shaft does not extend far enough through the top for the nut to grip. The washer and nut want to sit on the outside of the body, but the thread just is not long enough to hold.
This usually has nothing to do with a bad kit. A few things add up to make the body slightly too thick for a standard pot shaft:
- Semi-hollow bodies have a solid center block, and the top is thicker toward the middle where the pots sit.
- If you applied a thick finish coat, you may have added a few millimeters to the top without realizing it.
- Some pots have shorter shafts than others.
The fix: countersink the washer into the body
The cleanest way to solve this is to recess the washer slightly below the surface of the body so the nut has enough thread to grip.
Here is how to do it:
- Grab a 12mm countersink drill bit. Any hardware store has them.
- Put it in your drill and set the drill to a low speed.
- Hold the drill very upright over the pot hole. This is important. A tilted drill will widen the hole unevenly.
- Start slowly. Once the bit has bitten into the top, you can speed up gently.
- Stop every few seconds to test-fit the washer. You want the washer to sit just below the surface of the body, not on top of it.
- When the nut threads catch and tighten properly, you are done.
Cleaning up the recess
Once the washer fits, the knob covers the hole completely and no one will see the countersunk edge. But if you want it tidy anyway:
- Run a small piece of sandpaper around the edge of the hole to smooth any fuzz.
- If the countersink exposed bare wood, use a cotton bud to dab a bit of the same dye or finish you used on the body. Let it sit a few seconds, then wipe it down. The knob will hide this, but the cavity will look clean if someone peeks.
Watch the full demo
Have you run into this on your build?
If you hit this issue on a kit, drop a comment below and tell us which model and what finish you used. We are building a list of common build-day snags so other builders can learn from them. If you solved it a different way, even better. Share what worked.