1971 Martin D-18 Neck Reset
A customer brought in this 1971 Martin D-18 in desperate need of a neck reset. Martin didn't start using adjustable truss rods until 1985 so when one of these guitars has a neck issue, it can be a pretty in-depth process.
Here, you can see the neck is severely forward bowed and that the tops of the frets are quite a bit lower than the bridge. This will result in high action.
When a straight edge is placed on the tops of the frets, it should sit just above the bridge on an acoustic guitar. Here you can see it is quite a bit lower.
A slotted straight edge is also used on the neck to read the fret board while ignoring the frets themselves. This highlights the forward bow as well.
After removing the old frets and sanding the fret board, we place to frets in the neck to measure the height against the bridge again. This gives us a more accurate measurement of the adjustment needed for the neck.
We drill a small hole in the 14th fret slot to pump steam into the neck joint. This will heat and loosen the glue and allow us to remove the neck.
Once removed, we clean the neck joint of any residual glue to assist in a perfect fit upon reassembly.
When placing the neck back in the slot without glue, you can see the gap between the fret board and the body.
we glue the shim in place and clean any overflow. A clean surface is essential to a proper fit and finish as it allows the two pieces to fit closer together and for the glue to spread evenly.
After applying glue to the neck and slot with the shim in place, we clamp the two back together. Here you can just barely see the shim, filling the gap perfectly.
The bridge had been lifting slightly on this guitar, which the customer decided to have repaired as well. This involves fashioning a new bridge. Typically this would be done first to ensure it lines up properly with the frets and neck, but there were no issues in this case.