Trouble Understanding Compound Radius

[pariah223]

So i know that a compound radius is a tighter smaller radius at the nut and a larger radius at the bridge end of the fingerboard.. but what troubles me about it is this.. If your radius at the nut is smaller... as you go down the fingerboard and the radius gets bigger, so is the thickness of the soundboard right? and wouldnt that cause trouble getting low action? IM sure im missing something obvious but it just dosnt seem to make sense to me yet. Thanks

[westhemann]

You are missing the part where the nut is one radius(usually 10") and the bridge is another(usually 16" or so)..so the action is ideal.

[chops1983]

To help you visualize it, draw the two ends of the fretboards with the radiuses you want and start the curve at the required centre thickness of the fretboard from a straight line which would simulate the bottom. If your nut width is less(43mm) with a tighter radius(10inch) than your last fret (57mm and 16inches) the edges should even out. Put pen to paper and let us know your results.

[pariah223]

heres another question. I had a little trouble when i routed the compound radius into my fingerboard. Test piece worked fine as usual but then i ended up going a little farther then i wanted to and the thickness of the center of the fingerboard at the nut end is around .200 and at the bridge end is about .23 .. is this too thin or should i be fine? Only real issue i see is maybe my side dots might look odd.

[Doeringer]

Will it be functional and work? probably, but I think you would loose tone(?) I'm not sure how much, just putting the educated guess thingy on your question.

[Geo]

If your radius at the nut is smaller... as you go down the fingerboard and the radius gets bigger, so is the thickness of the soundboard right? and wouldnt that cause trouble getting low action? IM sure im missing something obvious but it just dosnt seem to make sense to me yet. Thanks

Think of it as adjusting the angle of the playing surface in the same way that the neck angle adjusts the angle of the playing surface. You just raise the bridge a little, as if the neck had been angled back slightly more. The effect is the same as far as the top surface of the fingerboard is concerned.

...assuming I understood your question.