Bar Refret on a Vintage Martin

You don’t see these everyday! A while back our buddy Mark brought us his vintage Martin 0-18K (koa) for a refret, which is usually a very run-of-the-mill job for us here – except for one thing. This instrument comes from a bygone era when C.F. Martin guitars were made using bar frets. Bar frets differ from modern “T” style frets in that they are each a solid bar of nickel alloy from top to bottom and are driven into relatively large slots in the fingerboard. They don’t have a tang, barbs or a mushroom-shaped crown like modern frets. The wire is sold in thicknesses ranging from .045″ – .060″ wide, and the frets are installed using a compression-fretting technique that helps stiffen the guitar neck by very firmly wedging each fret into it’s respective slot. Around 1934 Martin started transitioning from bar frets to modern “T” frets and they began using steel reinforcement bars to stabilize their necks. (They wouldn’t start using actual adjustable truss rods for another 50 years… but that’s another story.) Here’s a bit on my process when we do a bar refret.

To remove the original frets I used the hot tip of a standard soldering iron to heat the entire surface of the fret. This melts the hide glue that the frets were originally glued in with and helps to release the fret from the slot. Once the glue was hot I very slowly and very gently applied back and forth pressure with a modified end nipper to ease the frets out of their slots.

As you can see, the fret slots are quite a bit wider than modern slots. You can also see in this photo how low the original frets were. There wasn’t enough fret height left to level out the inconsistencies in the board itself.

Typically when we’re doing a refret we level the board with our Plek machine after pulling the original frets. Since this is a very old instrument and the ebony fretboard is already on the thin side, we opted to clean up the original board a just a little bit and then just level the frets tops themselves. Luckily, bar fretwire is plenty tall, so the least invasive choice was the right move in this case.

Some luthiers like to peen mirco-barbs into the bottoms of bar frets with a chisel to give them better mechanical grip in imperfect fret slots. I prefer not to do this, as the barbs can leave visible gouges in the fretboard surface along the edge of the slot. I very carefully measured the width of the slots and used fretwire that would provide a tight fit when pressed in. I also like to use a little dab of wood glue as an insurance policy.

After filing down and beveling the fret ends, I loaded the guitar into our PLEK machine and leveled the frets to an average height of .050″ up and down the neck. This is a good height for bar frets because it builds in headroom for future fret levels without feeling like speed bumps on your fingers. The PLEK makes this much easier to do than by hand, and is far more accurate as well.

After the PLEK finished it’s leveling process I took the guitar out and polished the frets and made a new bone saddle – and this old thing really came to life! These frets should be good for another hundred years!