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What ya got???
I had an idea that didn't pan out for a compound radius so looking for ideas.

I've looked at this one plan:
http://www.eguitarplans.com/Fretboard_R ... _11x17.pdf
But I'm not sure if it will do a compound radii or not.
It's simular to the type Mario Proulx uses and I'm thinking about making one like his but not sure where to get the self alining bearings for that.
I would like to see some setups though.
oh yeah, the ones for a sander probably won't do me any good for now since I can't afford to buy a large enough belt sander for thoses and I really don't have the room for one now.
But still don't mind seeing them .

There was one in the back of one of the somogyi books. He had a jig set up to use on a belt sander. I will see if I can find where I saw it.
Eddie

it might have been good if I read the whole post...
Eddie

Yeah, I saw that one. Pages 127-128 " Making The Responsive Guitar ". Hmmm, I think that could be adapted for a compound radius. Being it has the long travel north-south my sander just might work then. I'll have to revisit that concept.

I built one from the plans at Luthiers Cool Tools, and it works well with either a compound or simple radius. The cool part about it is that instead of using a belt sander, it uses a router with a bowl cutting bit in it. It doesn't take up much space either.

I radius my boards on a CNC now, but the jig I built from luthierscooltools.com plans worked very well for me before I got into CNC.

Dave

Chris, here is a picture of my old one.

Now I use one similar to this, at the bottom of page http://www.frets.com/FretsPages/Feature ... ngs05.html

Chuck

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Here's my old one too:

Compound Radius Jig

Cheers,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

Dave did you design a new one? And if you did why? Any concerns with the old one? It looks pretty slick.

Thanks Dave, Just what I was looking for with all the parts info.

This is my version of the Charles Fox jig I learned in his Modern Lutherie class. Very similar to the Collings device shown in the link above. At this point I have used it with double sided tape, I still dream of vacuum clamping technology in my shop.

I added the adjusters on the side, they help with the initial set up. It looks like the down side to this contraption is that it works with the FB off of the neck, I would consider being able to do this with the neck attached to be an advantage. I got some low friction tape from Mc-carr that is on the "wheels" now, that was a big help for smooth operation.
Rob

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I don't have vacuum clamping either, I am able to bolt the fretboard extension since it is a bolt on extension.

Chuck

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The one thing I like about the sanding jigs is that it sure would make sanding inlays down in the FB a lot faster.

Nope, this is the first and only one I made. I have a 3D CNC Spindle (ShopBot) now - still trying to work out the s/w and drawing side of things, but I'll be using the CNC to do jobs like fretboard radiusing in the near future.

One tip that isn't on my webpage is to make sure you line the center of the fretboard up with the top of the swinging arm's arc. If you are just a little bit off, you end up with a f/b that is thicker one side than the other! DAMHIKT!!

Cheers,
Dave F.

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Cambrian Guitars

"There goes Mister Tic-Tac out the back with some bric-brac from the knick-knack rack"

Seems like one could make a router sled with a long compass at each end and a fixture to hold down the FB blank while guiding the long compasses at each end.

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In my understanding, a long compass is a great tool when the radii are too big for a regular compass. I don't see the advantage when we are somewhere between 7" and 20" radii, router on a stick trick and make the wheels.
To convert the sander jig like the Fox or Collings to a router jig could be done with springs as done on the Brunner shaper neck jig.
http://www.youtube.com/watch?v=d4ubNo3pS0g

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Won't work with a compound radius, tried it last weekend. If you put the pointed / long compass ends on the fret board block and use the router sled as the span it won't cut a radius. It moves the edge of the FB in a straight line. If you put the long compass ends on the router sled it won't let the ends stay on the span ,it binds and you would have to twist it.
This is as far as I got with working on it until I decided it wouldn't work. It will for a single radius and you could put the a the angle as a slot so the pins would ride in the slots to hold it in place.

The advantage I'm thinking of is that the radius on each end could be adjustable and you wouldn't need a jig somewhere between 7" and 20" tall. Let me ponder this a bit, I think I may have just come up with a way to do it sort of.....

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Just remember that the long compass doesn't act the same as a curved surface. Just like if you were to extend the router bit 1" beyond the piont you would not increase the radius by 1". It just doesn't work like that.

Here is a picture of one I've been working on.



It's an alignment fixture used to position the fretboard for consecutive passes under a thickness sander. The concept is that as the fixture rotates across 2 radiused blocks...a large radius block at the rear and a smaller radius block at the front, a laser pointer is then used to align the fixture on a focal point (the target). If a router was going to be used instead of a thickness sander, then a shaft could permanently attatch the fixture to a universal joint mounted on a swivel located at the target position. The fixture could then be moved back and forth on the rear radius block as the router was slowly moved down the length of the fretboard.
I've only just finished making the the one in the drawing, and don't know how practical it will be in actual use. Anyway, I hope I've explained this well enough so as to be understandable.

I love the compound radius jig and concept, really gets the brain working. I can understand the idea of adjustable, however, it is not that hard to make a set of wheels in various sizes. My regret on the current jig is that I made it too small, it would have been cool to have enough space to do a bass FB, then there is some variation that would be available with placement on the jig, all the way to one side would be flatter, the other way would be rounder. When bass time comes around in my shop, it won't be too hard to make the same thing bigger. For now the jig works well and I am happy with the arcs it produces.

I may make a mock up of the router version, I have been wanting to play with it just for fun.
Rob

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Indeed, I make mine on a CNC machine so this is purely academic for me

I'm thinking along these lines:
Two steel rods or pipes that run kind of parallel to the fretboard

An inverted V also made from rods or pipe perpendicular to the fretboard on the router sled with a hole at the apex for the bit. This would ride on the long rods. Only one point of contact per rod.

Some kind of guide system to keep the router perpendicular to the ground, restrict the arc motion to perpendicular to the FB and to allow you to slide it from one end of the FB to the other.

With the long rods parallel, you'd get a constant radius FB.

If you made the rods converge at the nut end, you'd get a compound radius but you'd need to adjust for height as the FB would get "shorter" at the small end.

I've thought of an implementation but it's got a lot of parts and would be kind of complicated to build.

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The plans at luthiers cool tools seem to me anyway to solve this problem. The basis of this plan is a router sled, but the way that it handles the radii at each end of the fretboard allows the creation of a compound radius rather easily. It uses a radiused guide at each end of the sled that holds the fingerboard. These guides are easily changed to allow different radii, and it is quite simple to use either the same or a different radius on different ends of the jig. Pretty clever really.



Dave

Like this:

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Trevor Gore, Luthier. Australian hand made acoustic guitars, classical guitars; custom guitar design and build; guitar design instruction.

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How do you handle leveling of the fretboard when using a compound radius? With a single radius you can use a radiused sanding block to adjust the thickness of the fretboard in spots where it's uneven, but with a compound radius I guess you just need to get everything right from the start?

Ding ding ding ding ding....we have a winner!

I guess great minds thing alike, arch enemy .

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