curving neck

[clarksavage]

I could use some help in understanding the neck of my mandolin. Of course, if I look straight down the fingerboard from the top (and from the bottom) I see some "curve" where the string tension pulls up at the ends. I understand that a little bit is OK, but I wonder what a normal tolerance is before I should be concerned about it. The neck on this mandolin is not adjustable and the mandolin is still in warranty :-) . It is not easy to play as I get a few frets up from the nut (up at the 4th fret, Bm position, I notice it getting hard).

If I press down at the octave position, I can measure a space of about .010 in (.254 mm) at the 4th and 5th frets (on the G string). Does this sound right or is it a good measure to take to explain the situation to a repair person?

[sunburst]

To check the bow, press a string down at the 12th (or so) fret, and at the 1st fret. That removes the nut height from the equation. If you just press tha string down at the 12th fret, and the nut is too high, there will be a lot of clearance at the 4th fret even with a straight neck.
I usually just eyeball the bow in mandolin necks, so I can't really tell you in numbers how much bow is appropriate. Someone here probably can, though.

Of coarse, there are other neck and setup parameters to consider that are all interrelated, so checking and correcting the bow is only part of the set up.

[Michael Lewis]

You should need no more than .006" at the 7th fret, that is just over a tenth of a millimeter. You don't even need that much on most mandolins.

What John said about eyeballing the clearance is good but I want to add that you may need to go higher on the fingerboard than the 12th fret to find out how much relief you have. The tallest(highest) fret is the one you want to hold the string to up the neck. Sometimes the fingerboard suport sticks up a bit and that has to be taken into account.

From what you are saying it sounds as though you need to lower the bridge, then you may have too much bow in the neck. Get the relief correct and then lower the bridge. Have a qualified person assess the instrument, then decide whether to have work done or return it for warranty work.