fingerboard sanding to radius

[peter havriluk]

I've been practicing sanding the radius into a couple of fingerboards. First one, I sanded the fingerboard with a curved (like what Stew-Mac sells) block after double-sided-taping the fingerboard onto a glass plate. Second one, I taped the fingerboard to the channel of a shallow-u-shaped board 2' long with sides that confine the curved block to better align with the fingerboard.

I noticed that the fingerboard sanded freehand has less material on one side than the other, from roughly the 14th fret to the 20th fret. Now this is a 'practice' fingerboard and I'm not fretting if it is not usable, but I would like to gather some idea as to what kind of precision I need to maintain on future sanding projects. The second fingerboard, the one sanded in the channel, does not seem to exhibit much difference side to side, at least on initial measurement. I have found that marking the fingerboards with a white pencil helps control sanding evenly.

If my PC hadn't managed to trash its picture-loading software, I'd attach pictures.

Thanks very much.

[ken cierp]

Free handing a finger-board radius can be a frustrating and often a futile process. Whether using a curved block or not. To get it right you'll need a fixture where the FB is stationary and centered between rails. The sanding block needs to be made into a sled guided by the rails, mark lines on the FB to guide progress.

A properly contoured fingerboard that is already tapered will be thinner on the edges at the edged at the 20th fret than it is at the 1st fret.

How accurate does it need to be? I think you already know the answer to that question be it the fingerboard radius or anything else related to playabilty.

[peter havriluk]

Ken, thanks for your reply and advice. I think my second solution fits your definition of a 'sled guided by the rails' in that the shaped block fits against the side rails with enough clearance to slide without drag but rolling from side to side is discouraged, the sled binds if it isn't level to the fixture. Interesting part of the learning journey.

Much obliged.

[John Parchem]

I have contoured a few fret boards by hand with success. I radius the fret board before I cut it to shape. My sanding block is the 18" aluminum sanding beam stewmac sells; I use it with 80 grit paper. As Ken suggests I also mark the top of the fretboard with a pencil so that I can watch for even progress. The long beam helps keep the length consistent. Sanding before I profile the fret board avoids the tendency of sanding the nut side thinner.

[Tim Benware]

I'm working on a jig now to rout in the radius on the FB. I have all the parts cut out and am waiting on the roller bearings. May be a while before I complete it though as I will be moving into my new shop soon and have some things I want to do with it first. Will post pics when I'm done.

[Lonnie B]

Tim, looking forward to that posting as I too will be radiusing the fretboard on my next build. I have no experience at all on this process so you know I'll be watching closely.

[Kevin in California]

I have done 7 fret boards, not a lot I know but that is my experience level. I have done them all by hand with a radiused block, and they have all come out reasonably accurate. I don't mean "within .005" accurate, but to my eyes, very close. I just mark with chalk and watch my progress closely. At the end I taper the fret board down from about 13 fret into a slope where the end is about 1/16" thinner, because I read somewhere to do this. :>)
Acutally it does help in how the line of the fret board looks as it comes across the top and avoids the "kick up" look, and it helps with keeping some potential buzzing at bay.
I like the rail idea though, and I may try and rig something up to try, certainly would give consistent accuracy.

Kevin