There are three main factors to consider when intonating a dulcimer, the height of the nut, the height of the bridge, and the position of the bridge.
There is a simple system for intonating a dulcimer which is called the "nickel and dime method" where a dime is placed on the fingerboard just above the first fret so that the side of the dime is touching the nut-facing side of the first fret, so the dime is between the first fret and the nut. A nickel is placed on top of the 7th fret and is between the 7th fret and the string.
Generally, the nut and bridge should be lowered until the string is just barely touching the face of both of the dime and the nickel.
If your fret wire is taller than average, the dime may not be useful, since the fretwire may be taller than the dime. If that's the case, it may be a little bit more complicated. Using a dime only works for short fret wire, such as a mandolin or ukulele fret wire, and if the instrument has guitar or jumbo fret wire, then determining correct intonation at the nut might be more difficult.
If you set the string height or "action" using this method and all goes well, but your instrument is still not well intonated, then you may need to adjust the position of the bridge itself.
To do this, tune the string up to the desired note, and then using a tuner check the intonation at the octave fret.
If the octave fret is sharper than the root note, then the bridge needs to be moved closer toward the nut. If the octave fret is flatter than the root note, then the bridge needs to be moved further away from the nut.
I hope this helps
Nate
updated by @nate: 09/27/25 08:04:05PM