Fretless conversion

For many years I was strictly a fretless player. I did my first fretless conversion on my second bass about 15 years ago – a composite necked Peavey B-Quad, which was quite the chore for my younger self! Over the years, I’ve defretted several of my basses, including my now main instrument, a 1974 Ovation Magnum. I feel like I’ve gotten pretty good at it, and have learned some tricks on how to make a fretless instrument play well. There’s more to it than just a lack of frets!

Last week my friend Kirk asked me to do a fretless conversion his old Ovation acoustic bass. Kirk is predominantly a guitarist, and this would be his first fretless instrument. As setup is vitally important to how a fretless instrument not only plays but sounds, I spent a few minutes explaining the details and determining what Kirk wanted out of his bass. With Kirk’s specifications in mind, it was time to yank some frets!

I’m not sure what sort of abuse this bass saw before I got my hands on it – this fretboard was UGLY. It looks like there’s  some sort of grain filler or wax in there. Yuck!

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After taking measurements and documenting the current setup, I removed the strings and very carefully started pulling the frets out. Fingerboards tend to chip when removing frets, so it’s important to use the proper tools and utilize good technique. I know Jaco probably yanked them out with his teeth, but I use Stew-Mac’s Fret Puller (which is expensive but still the best tool I’ve tried so far). I start at one end and slowly walk the fret out, instead of just yanking it straight out. (Sometimes frets are glued down, in which case I apply heat with a soldering iron to melt the glue before pulling the fret.) Lucky for me, these frets came out fairly easily and wouldn’t require any extra work filling in chip out. Huzzah!


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Next I prep the fret slots. When the frets are first pulled, they pull up a bit of wood with them, and they look pretty rough. I first knock down the high spots with a long file, and then cut the slots clean with a Dremel and a tiny drill bit:

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You can see here how much cleaner the slots look after re-cutting them. In this picture, the top slot is untreated, and the lower slot has been cut with the Dremel:


Next I clean the slots, removing any debris that may be left over:


As this was Kirk’s first fretless bass, he wanted some visible fret lines to use as a guide. Some people choose to use plastic for fret lines, but I feel that the plastic wears at a different rate than the fretboard itself, and makes the fretboard feel bumpy. I opted to use maple for the fret lines instead, which would wear evenly with the rosewood, and would look more organic. I cut some maple veneer to exactly fit each fret slot, and glued it in with Titebond wood glue. (I could have glued the maple in using superglue, which would have been a lot faster – but this fretboard appeared to be very porous, and the superglue would have soaked into the wood, possibly leaving dark spots.)


The next day, after the glue had dried, I cut the maple down flush to the fretboard with a razor:


Now came the most critical task: leveling the fretboard. If you’ve talked to me or read this blog before, you know how much I harp on fretwork being critical to the playability of any guitar. It is equally vital to have a fretless fingerboard be absolutely dead flat. On a fretted instrument, you want each note to sound clean, with no buzz; on a fretless instrument, you want each note to buzz equally with all the others. This is where the “muah” sound of a really good fretless bass comes from: the string just slightly buzzes against the fretboard, just in front the point where the finger holds it down. If there’s any low or high spots in the board,  the muah sound is replaced with a horrible, unmusical buzzing that sounds like a swarm of bees. Not cool.

Just like on fretted instruments, I level the playing surface on my neck jig, using a flat beam and radius blocks to get the board dead flat and to true the radius. Note to DIYers: WEAR A MASK! Wood dust is nasty stuff, and is in many cases poisonous! Don’t think just this one time won’t hurt – mask up EVERY TIME.

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This particular neck was pretty far from being flat, so I had to take off a lot of wood to get it right (When I say a lot, I mean just a fraction of a millimeter. To a guitar tech, .01mm is HUGE!). This was partly what I intended anyway – the fretboard was pretty gross when it came in, so I wanted to down to the good wood. I started with 80 grit sandpaper, and worked my way up to 1000 grit, at which point the wood starts to shine like glass. I hadn’t even put any finish on the fretboard, and it already looked this good:


To seal and protect the rosewood, I applied several coats of gunstock oil. It looks a lot better than when it came in, methinks:

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Next was a vitally important step: the setup. As I see it, there’s generally two options for fretless setup as it relates to tone: low action will bring out the buzzy, muah tone that many bassists favor, or high action will provide a louder, deeper, more upright-like tone. Either way, the nut has to be cut very close to the fretboard, so that it will play easily in the lower register, and won’t throw the intonation off. Fretless is hard enough to play in tune as it is, and if the nut is too high it becomes almost impossible! I made a new nut out of bone, and as you can see: when I say cut it low, I mean LOW!

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Generally I like to see fretless necks almost dead straight: for low action, I’ll introduce a tiny amount of relief (perhaps .05mm), and for higher action I’ll set them completely flat. For Kirk’s bass, I set the neck totally straight, then cut the bridge saddle down to match the 30cm radius and to set his action at 2mm and 1.75mm on the bass and treble side, respectively.

And done! I put the bass through it’s paces for a bit, double checking my work (as always), and was quite impressed with the sound. The Ovation bowl design really brought out some zing in this bass, which really works to bring out the fretless qualities. Sweet! Now all Kirk has to do is learn how to play it in tune…

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