Sanding Bars - Luthier Tips du Jour Mailbag
In this episode, Robbie O’Brien demonstrates sanding bars and how to level sand with precision.
Video Transcription
[on-screen text reads: Luthier Tips du Jour Mailbag]
Mailbag question: I'm having trouble with fret buzzing and I think it's because of my fretboard prep. Can you offer some advice?
Robert O'Brien: Today's Tips du Jour Mailbag question comes to us from Michigan. "Robert, I'm having trouble with fret buzzing and I think it's because of my fretboard prep while building. Can you offer some advice?" Jeff in Michigan.
Jeff, I think you're on the right track. I like to refer to building a guitar is like building a house. If the basement is square and plumb, by the time you get to the roof, everything fits. So that's extremely important. Before you even get to pounding those frets in, make sure that everything is flat, square, plumb, to use that analogy, before you start pounding frets in. Let me show you how I prep that.
Leveling the fretboard
So Jeff, here's a classical guitar. It's on my bench. It's to the point of leveling the fretboard before I start doing my fret work. Now, one thing that helps me is these aluminum sanding bars that I got from LMI. These are machined up to two thousandths of an inch tolerance over a 24-inch length. They come in several sizes, and I use all three of them, the longer one, the medium, and the shorter one, when I'm doing my leveling.
They have a little bit of heft to them, so it helps. You're not going to be working yourself to death as you're leveling, but they're not too heavy that you're going to feel it when you get done. All four sides are machined to that two thousandths of an inch spec, and it has nice square edges so when you put your Stikit paper on there, you can tear it nice and easily and all of the sides are perpendicular to each other. So, really, just a fantastic tool.
So I start with about an 80 grit, and one of the cool things about having all four sides machined is you can put various grit sandpaper on your sanding bar here. So I start with about 80 grit. Now, my classical guitars have a forward pitch on the neck, so there's usually a little slope down in here. So I'm using it taking it here and here. A steel string guitar would perhaps be the opposite, depending on what you're doing. So I come in here and make sure it's extremely flat. If you want to chalk it up, make sure it's extremely flat, then you can switch it over and go to 120, 150, 220, 320, as far as you want to go.
So that's the first step. Just make sure that that thing is flat before you even get ready to install your frets. Of course, there's a lot of other prep work you can do here, and there's videos and things available about that, about how to do fret work, but that's the first step. That's your foundation. Make sure that foundation is nice and flat, square, plumb, etc.
Leveling the frets
So here's a steel string guitar and the frets have already been installed; we have to level them. Now, you think they're level, but they're not. There's some tolerance differences in the manufacturing of the wire and stuff. So you got to come in and level them, and I like to use my medium-sized bar for that. Start with about a 220 or even a 320 and just run it across the tops of the frets. This one has a radius on it, so I'm going to maintain that radius. You can put a sharpie across there, and when you see the scratch pattern on there, you're level. Up here on the fretboard extension where it usually tapers off about a 64th or a 32nd, I come up and use my smaller bar like so. And there you have it.
So Jeff in Michigan, thank you very much for your question. And remember, do your prep work properly before you even start installing frets. If you do that, it'll make it much easier when it comes time to do your setup work as well. And happy building.
[on-screen text reads: More Luthier Tips and online courses available at www.obrienguitars.com. Private and small group guitar building and finishing instruction available.]
