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Hi Guys,

I built a radius jig similar to a lot we see on the forum. Essentially it uses the end of a 1/2" straight router bit to shape the fingerboard radius. I run the jig long ways down the board. So the movement is: Start on base side by heel and move toward nut. Come down the treble side from nut toward heel. The continue the process moving from the edges toward the center. This seems to work fine, but usually near the 2nd or 5th string area of the board you will see small swirls in the wood from the end of the bit. I always sand and level the boards afterwards with a 18" long radius block to remove the swirls. But often times there is some tearing of the wood leaving the wood very rough compared to the other areas. This has me doing a lot more sanding to remove the tear then the rest of the board needs. It almost takes away the benefit of using the jig.

BTW: The wood is 90% of the time Rosewood or Maple and is Quartersawn.

The only thing I can think of is the posibility of the bit being dull on the top edge. I use this bit for lots of steps in the Neck building process. It seems like it is still sharp and I don't have issues in other applications I use it for.


THoughts?

J

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Joe

I would try a new bit ...

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Yea, a new bit and perhapse taking smaller bites when you go down the fretbaord. For myself, I try not to route more than 1/8'' at a time. Also, I first route the border all around the fretboard with a climbing cut to avoid tearouts. Then I go up and down the fret board. But that doesn' teliminate tearouts near the fret slots.

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Alain Moisan
Former full time builder of Acoustics, Classicals and Flamencos.
(Now building just for fun!)

I would think a radius sanding jig that swings back and forth on a beltsander would do it better with no chipout problems. Grizzly sells a nice set-up for that. Model No. G0574. I'm considering getting one.

Thanks for the replies.

1) New bit may do the trick. I also use this bit for shaping the back contour, using the top edge as well. So its possible that its getting dull on the top and not the sides.

2) I actually do the radius in two or three passes. The first one has the bit about 1/16" over the center of the board. (9.5 or 12" radius usually). This allows only the first 1/2" of the fretboard to be radiused. I then lower the router to where its not quite touching the fretboard and do this again. This leave a very small patch down the center to be done. I will then move the router the last little bit and clean it up. I have a small pitch to my jig that allows the nut area to be cut a bit deeper than the heel. Because of the taper of the fretboard, if I radius at the same depth the entire way, the fretboard appears thicker at the first frets and thinner at the last. By applying a bit of a pitch, my fingerboards look much more uniform down the entire edge.

3) A swing jig over the sander sounds like a great idea, but its $1200 or so for that set up from them. While I do a large number of neck per year..the first year that tool would cost me $10 per neck to use. I would think that until you can get the cost of that machine down to about $1 per use, I would have to carry the overhead for about 10 years..

I do have a line on a 6x48" belt sander locally. I may grab it this weekend. I would then have to fabricate something that swings to use it in this application.

Joe

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Joe

These jigs work best with a 'bowl and tray' bit. The radius profile allows progressive entry into the cut which eliminates tear out.



Cheers

Kim

Thanks Kim. I've bought several of those bits, but the shaft never is long enough. I think the total length of the bit needs to be about 2-1/4" for my current jig to work. I'll look online again for a longer bit.

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Joe

Thanks Todd. That is the direction I am doing. I stand at the heel and work, but same idea. I radius my boards after they are glued on me electric necks.

If I ever get a chance and a bunch more time I'd like to build a radius jig similar to yours. My router does not lock into a sliding carriage like yours. It slides down two rails.

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Joe

The "bowl" bit Kim described solved all my tear out problems. I was getting some chipping with a straight bit even with climb cuts.

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It's not what you don't know that hurts you, it's what you do know that's wrong.