Neck Straight???

How do you tell if a neck is straight or not? Are there any tricks? My dad gave me an old baritone uke and I can't tell. I think my eyes are playing tricks on me.

Might get a better response in Tech Support forum?

Hold it up to a window pane- ought to be pretty close

Sight down the neck from the headstock end and look to see that all the frets are level and parallel. If the neck is twisted this should reveal it.

Place a straightedge on the fretboard. You'll need something short enough to fit between the nut and the bridge. If it's narrow enough (steel ruler on edge works well) it will fit between the strings without having to remove them. It should be touching all (or nearly all) frets. A little bowing can be tolerated around the middle, but not much.

The straightedge should also end up just about at the top of the bridge. If it's way high, the neck is backbowed which will cause the strings to hit the frets causing buzzing. If it's only mildly bowed it can be helped with a taller saddle until you get the action you need.

If the bridge interferes with the straightedge or the straightedge nearly hits the soundboard then the neck is bowed inward and the action when strung will make it nearly unplayable. No amount of nut or saddle adjustment will compensate for a neck this badly bowed.

These are just general guidelines to check for obvious errors. Luthiers and repair techs will know more and what to do about it.