Complexity is the Enemy of...

[Eric Knapp]

Hello,

I'm suffering from something that might be common. As a rookie I'm always trying to do things in a way that is too complicated. For example, I'm about to start working on my fifth way to make a compound radius fretboard. I just finished making number 4. It's a router-based system that might even work but is too fussy to get accurate. StewMac suggests using multiple sanding blocks and I think I'll try that next. I don't have a budget for buying the sanding blocks so I'm going to attempt to make a batch with some salvaged 2x4s. I don't have a big stationary belt sander like many of the YouTube videos show to use. I also don't have any metal-working equipment. I have several routers so I tried using those.

This complexity complex is very common in the software development world. My students sometimes come up with the most convoluted and complicated solutions for projects I assign. When they see my solutions they are amazed at how simple and clear they are. I got that skill from many decades of full-time experience. I might be doomed to convolution as a guitar maker.

Is there any hope for me?

-Eric

[Bryan Bear]

You have already posted a picture of a compound radius tool that couldn't be more simple. After slotting a board, I cut the fretboard taper and tape it down to a flat surface with double sided tape. Then I carefully use a handplane to put the radius on. By following the taper of the board and the imaginary string paths you create a compound radius. All you need to know is what radius you want at the nut and plane to that. As long as you are planing flats, the taper of the board will dictate the radius at the end (you don't even need to know what that measurement is. I like to chamfer the edges of the fret slots to reduce the chance of tearing them out. You still need to be careful and have a sharp iron. You also may need to re-chamfer the edges of the slots as you go if you are cutting below the depth of the chamfer.

[Alan Carruth]

I radius the board by hand as Brian does, after assembling the neck to the body. This is about the only way I've found to get the shape of the fingerboard right. It's simple once you've developed the tool chops.

[Bryan Bear]

Alan, How do you handle supporting the part of the board that extends past the neck? I was always worried that it would deflect too much while planing. I tape mine down to a narrow piece of granite and put that in my vise, but I'd love to hear a simpler way. When I do a bound board, I put the radius on then glue on the binding and bring them down flush to the surface. I think I'd like to be able to glue the bindings to the fretboard and neck at the same time.

[Chuck Tweedy]

After slotting a board, I cut the fretboard taper and tape it down to a flat surface with double sided tape.

How do you handle supporting the part of the board that extends past the neck?

Bryan, sorry, but these 2 statements seem to be inconsistent.
If you stick the tapered and slotted board down to a flat surface, then radius (which is exactly what I do as well) ...
Why are you concerned about the body overhang? It is fully supported - no?

[David King]

I glue my fingerboards to the necks and then freehand sand them on a big belt sander with scored guide lines on each edge and various radius cauls to check progress. The final sanding is done with a flat sanding stick with a tiny bit of backbow introduced via the truss rod. Again like the others I concentrate on establishing the string paths and then fair out the curvature between them. The whole process takes maybe 30 minutes from start to final 800 grit wetsand and polish on a 5 string bass fingerboard.

[Bryan Bear]

After slotting a board, I cut the fretboard taper and tape it down to a flat surface with double sided tape.

How do you handle supporting the part of the board that extends past the neck?

Bryan, sorry, but these 2 statements seem to be inconsistent.
If you stick the tapered and slotted board down to a flat surface, then radius (which is exactly what I do as well) ...
Why are you concerned about the body overhang? It is fully supported - no?

The second post was in response to Alan radiusing after the board is attached to the neck and body. I would be interested in trying that out but I feared that there would be deflection. I currently use a marble slab and tape; whatever deflection occurs there is trivial.

[Chuck Tweedy]

got it

[Eric Knapp]

I radius the board by hand as Brian does, after assembling the neck to the body. This is about the only way I've found to get the shape of the fingerboard right. It's simple once you've developed the tool chops.

I am working on my recovering chops. But I have no frame of reference for how this works. The descriptions are not enough, I need to stand next to someone and see what they are doing. For now I need a way to make a fretboard that is accurate without having an example to follow or someone to show me how. I've made a bunch of radius sanding blocks so I can start getting the feel for the various radii. I'm cutting up old scraps of hardwood to the size of fretboard blanks and trying to put a compound radius on them. From there I'd like to try it all, slotting, radiusing, and binding on a blank that's not one of my good ebony ones. It seems to be part of the learning.

Thanks,

-Eric

[Eric Knapp]

You have already posted a picture of a compound radius tool that couldn't be more simple. After slotting a board, I cut the fretboard taper and tape it down to a flat surface with double sided tape. Then I carefully use a handplane to put the radius on. By following the taper of the board and the imaginary string paths you create a compound radius. All you need to know is what radius you want at the nut and plane to that. As long as you are planing flats, the taper of the board will dictate the radius at the end (you don't even need to know what that measurement is. I like to chamfer the edges of the fret slots to reduce the chance of tearing them out. You still need to be careful and have a sharp iron. You also may need to re-chamfer the edges of the slots as you go if you are cutting below the depth of the chamfer.

This sounds like a good goal since I love planes and can keep them sharp. What size plane do you use? I still would like to see someone do this live to understand the subtle details you probably are even aware of anymore.

I'll get there, eventually.

-Eric

[Randolph Rhett]

Eric, I think you already have done a compound radius with a handplane (or perhaps spokeshave) without realizing it. It is the same concept as your neck carve, just shallower. It is also the same concept as a cabriole leg on furniture. Once your blank is tapered, mark on vertical edge a constant thickness, say 3/16". I'm assuming your blank is 1/4". Mark a centerline. Plane from the centerline at full thickness of your blank to the edge line. You now how two flat wedges narrower at the nut end and wider at the bridge end. You also have a 1/4" ridge and 3/16" edges.

Now make a mark half way between the center ridge and the edge of the fretboard at the nut. You will be marking twice, once on the left and once on the right. Do the same thing on the bridge end of the fingerboard. If you connect the left to left marks and right to right marks, you have now bisected your two wedges. These new lines describe a shape similar to the fretboard outline. Plane the area flat between these new lines nocking off the ridge created in the first planing you did.

If you redraw your centerline you will see you have two wedges now on each side of the centerline. Again, bisect each wedge and plane the new ridge flat between them. Repeat this procedure as often as you need to develop smaller and smaller wedges. Do it an infinite number of times and you will describe a section of a cone, or the theoretical ideal compound radius. In practice you need only do it a couple of times and then smooth with sanding paper.

Again, I assume this is the same as you are doing with the neck shaft, just with a much bigger difference between the height of the centerline and the edge of the neck. With a sharp plane putting in a compound radius is not that hard. Of course, if you need it it be EXACTLY 10" to 16" compound then I think you need some complicated jig. You could build the MOTHER of all complicated jigs... a CNC machine. That is what I did, but it took up nearly all my free energy for nearly two years to build it and learn how to use it. Otherwise, a hand plane will make short work of this task.

[Eric Baack]

The CNC is a nice tool to have though. I've done a constant radius with mine by just hand programming some G-code in a loop.

[Bryan Bear]

You have already posted a picture of a compound radius tool that couldn't be more simple. After slotting a board, I cut the fretboard taper and tape it down to a flat surface with double sided tape. Then I carefully use a handplane to put the radius on. By following the taper of the board and the imaginary string paths you create a compound radius. All you need to know is what radius you want at the nut and plane to that. As long as you are planing flats, the taper of the board will dictate the radius at the end (you don't even need to know what that measurement is. I like to chamfer the edges of the fret slots to reduce the chance of tearing them out. You still need to be careful and have a sharp iron. You also may need to re-chamfer the edges of the slots as you go if you are cutting below the depth of the chamfer.

This sounds like a good goal since I love planes and can keep them sharp. What size plane do you use? I still would like to see someone do this live to understand the subtle details you probably are even aware of anymore.

I'll get there, eventually.

-Eric

Perhaps I am leaving some points out but probably not much. It really is simpler than you might think. While you are practicing on hardwood scraps with your sanding beams, do a couple with a hand plane and see how it works.

As for what size plane I use, well. . . I use a #5, or a #4 it depends on the length of the board (a mando would need a shorter plane). Okay, if I am being totally honest, I use whichever plane is sharpest at the time.

As for more details of the actual process, Randolph has done a good job of detailing his process. I will say that his is way more involved and regimented than mine. I really just do it. It is not unlike rounding an edge with a block plane, just bigger. Think of the edges of the FB as the corners being rounded, but it is only one side of the edge (the FB side). I take a stroke along the corner knocking the 90 degree edge off. Since I am using a plane instead of a spoke shave the surface is flat and straight. Then I angle the plane a bit towards the FB edge and take another stroke. Now it is more "rounded." Keep in mind, I am taking very light cuts; mostly because I don't want to blow out the fret slots. Keep going and work toward the center more and more. Plane from the edge and move towards the center and repeat. The taper of the board will cause all of those tiny facets to get a little bit wider at the end than they are at the nut. This forms the compound radius. As you get away from the edge of the board, I find it easier to think of the string paths as my imaginary line to plane along. This helps me stay on line.

Other helpful things:
You can draw the arc of the nut radius on the endgrain of the fretboard and plane down to that.
You can draw a line down the edge of the board and plane down to that (much like dressing a rough board but you are curving the top surface)
Sometimes I will use my long level (it has a side that is actually flat) with sand paper glued on to sand along the string paths to check that my plane strokes are staying flat. The smooth planed surface easily shows what areas didn't get sanded.

I just typed out a long response that is probably much less helpful than just trying it out a couple of times. It will become clear once you are doing it. In fact, the very first time I did it was on an actual fretboard. I was laying in bed one night thinking about compound radius jigs and dreading making one. I wanted to start doing a compound radius but didn't want the hassle. Then the plane concept popped in my head. My plane chops are not all that great now but at the time they were pretty remedial. Even still, the next evening, I took my harbor freight #4 knockoff and went for it. I never even measured the nut radius, I just did what looked good. It worked fine.

[Brian Evans]

I thickness the rough fretboard, cut it exactly square, slot it, taper it, glue it to the neck, bind it, then radius it with sandpaper. I find it's a heck of a lot easier to do a compound radius than a perfect straight radius (if a straight radius is a thing). I use some templates to judge the radius.

[Chuck Tweedy]

THIS discussion in the library gives a good description - even though the subject is standup bass

[Bryan Bear]

Chuck that was a great thread and nice looking bass fingerboard you did. Do you use a bevel gauge and all that when you do a guitar FB? It feels like such a shallow radius would make that cumbersome. Perhaps I have been going too much by the seat of my pants but it works okay.

[Chuck Tweedy]

Bryan - No I don't use the bevel gauge when doing a guitar FB. The bass FB is huge, and with relatively extreme radius, so tools like that can be used.
I start with a flat board and use a super sharp block plane to cut an initial facet along each edge of the board as a first approximation of the desired curves at each end. I check this with StuMac radius gauges.
I then cross-hatch the board with white or yellow pencil so I can see what I'm cutting off after that (the first 2 facets are very obvious to see where you are cutting).
I keep cutting to get closer and closer to the desired end curvature, making sure to be following "string paths" while cutting. This is really fun with a well setup and sharp plane - taking uber-fine curls off the ebony board.
Once I'm, pretty close, I switch to sandpaper on a long flat (hard) block and sand in string paths to blend all the facets - checking radii all the time. This goes really fast with 150-220 paper.
Final check of radius, and on to finer grits up to polish.
It's a fast process.

[Bryan Bear]

Very similar to how I do it but I don't do the big facets first. I just do a more rolling progressive set of smaller (narrower) shavings by feel. I might try hogging off bigger flatter facets at first next time around and see how I like it.

[Eric Knapp]

Wow, everyone. Thanks for all of your input. Information like this is worth its weight in ebony. I am getting a much better picture in my head and I think I'm on the right track. I hope to share some results soon.

-Eric

[Alan Carruth]

Bryan Bear asked:
"Alan, How do you handle supporting the part of the board that extends past the neck?"

I glue it to the top..... As I said, I surface the fretboard after assembling the neck to the body. It's a hold over from when I started out making Classicals the old way.