Replacing inlays on a Les Paul

Here’s how to an inlay job bass-ackwards. A few weeks ago, I refretted Kirk’s Les Paul with stainless steel jumbo fretwire. It came out beautifully, and his Les Paul plays better than ever. This week, he came back and asked me to replace the trapezoidal inlays. D’oh! This is exactly the wrong way to go about replacing inlays. Typically this isn’t a difficult job, but this kind of thing is best done during a refret, before the frets are installed. I can’t fault Kirk for this – he didn’t know, and I certainly wasn’t going to refuse him simply because it would have been easier to do earlier, without the frets in the way. This was going to be an interesting challenge, so I gladly accepted the job. Here we go!

The original inlays appeared to be some sort of plastic, with an aged yellow look:


Kirk brought a set of pearl inlays he wanted installed, so I first checked them all by laying them on top of the fingerboard and made sure they mostly lined up with the old inlays. They looked close, so with a bit of work I was sure they’d fit. This was the easiest part of the job – everything would be harder from here on out!

First I would have to remove the old inlays. I had to somehow drill down into the old inlays, and route them out without going too deep, otherwise the new inlays would be too low. This was going to be tricky: typically inlays are installed before the fingerboard is radiused, so the bottoms of the inlay’s route would be flat – but now the fingerboard is curved. Plus now there are frets in the way, so I would have to be very careful not to cut too deep. Not to mention that I had no idea how deep the old inlays were, so I would have to guesstimate. Yikes! I hoped that they would be no deeper than the new pearl inlays, so I measured them as my starting point. Taking into account fret height (1.5mm) and the pearl inlay thickness (1.6mm), I chucked up a small cutting bit into my Dremel and made an exploratory hole into the middle of the plastic inlay, where it would be thickest:



I kept incrementally lowering the bit by .25mm until I hit rosewood. I was initially planning on trying to lift the inlays out whole, by getting under it in the center and lifting out. Unfortunately, this just wasn’t going to work – they were too solidly glued in. Instead, I opted to very carefully route them out. This was going to be very tedious work: I simply could NOT drift outside of the lines, or I’d be in big trouble. For some reason, I sensed that my original pilot hole was too deep, so I backed off the bit before I routed the entire plastic inlay out, and I’m glad I did.

IMG_1974IMG_1973Once I got the first inlay out, I could see what was going on under there. The plastic inlay was significantly thicker than the pearl inlays (1.9mm), and there was almost 1mm of glue on the bottom. I wasn’t expecting so much glue: my original exploratory pilot hole was too low. If I had routed the entire inlay at that original depth, I could have been in trouble. Saved by my Spidey Sense!

Now that I was able to accurately measure how low the bit needed to be, the rest of the inlays came out a lot cleaner:


Unfortunately, the old inlays were much thicker than the new pearl inlays, so I had to add a shim to each one. I glued some mahogany veneer to the backs of each inlay, and cut them to fit:


After sanding each inlay’s mahogany shim to fit, they were at the right height: just barely clearing the top of the fingerboard. Then I had to carefully reshape several of the inlays, as they were too big to fit in the original routes. This took a LONG time – they had to fit perfectly (well, as perfectly as possible considering I didn’t actually make them myself). If I took even the tiniest bit too much off, it would be visible. There was no room for mistakes, so I took my time with this vital step to make sure they were absolutely right.

Once satisfied with the fit, I glued them all down, and then filled the edges with black superglue:


This next part would have been easy if I had been doing this during the refret process. Each inlay sits up a little higher than the fingerboard:


Normally these would get sanded down flat when the fingerboard was being planed flat, and would be radiused right along with the fingerboard. Unfortunately, the fret job has already been done, so I had to file each of the inlays by hand:



I had to file the pearl down to the level of the fingerboard, and match the fingerboard’s radius – and the results had to be absolutely smooth to the touch. I roughed them in with a series of files, then varying grits of sandpaper, and finally polishing them out with ultrafine Scotch Brite. Needless to say, this took a LONG time, but the results were worth it. These were ultra smooth to the touch. Success!

After cleaning and oiling the fingerboard, three of the inlays revealed a bit of pearl dust had accumulated in some air pockets in the black superglue filler:


I couldn’t just leave those sitting there – these have to look awesome! So I very carefully cleaned them out with a razor blade, filled the spots with black superglue, and then sanded and polished them back out yet again.


This was a lot of work, but totally worth it. The new inlays look great, and feel amazing. Awesome!

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