Official Luthiers Forum!

should i sand down a slight belly in the neck to compensate for fret deflection , the neck wood is African mahogany with a ebony fret board ,22 frets.

If your neck is straight - and your fretboard flat when glued down - then when you fret it you should see a slight back bow to the neck as a result of the fret tangs being wider that the fret slot - I would leave this well alone as pretty normal - when you string, the tension will straight the neck and the rest is then managed with the trsus rod. Should be no need to 'sand' the fretboard in any place - just get them nice and straight before you glue up or fret.

Depends on if you're using a double action truss rod or not. Some guys like to put a small hump in the neck nd flatten it out before radiusing to assure relief in the neck after fretting.

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Old growth, shmold growth!

That's what I do when using a single-action rod.
I glue my fret board blank to the neck, level the board, create a slight hump, re-level the board, saw frets, taper, radius, polish, apply finish (if desired) and then install the frets. I've used stiff wood like Mesquite for necks and I want to ensure I can get relief.
It may be overkill but it works for me.
Dan

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