Is this totally whacko (using a laser) or is it brilliant*?

[belbein]

While waiting on some process with my Saga build, I turned to my POS mandolin to continue the process of tearing it apart. I noticed that the neck was (possibly) out of whack, and no matter how I measured it against a straight edge, I couldn't quite see it. So then it hit me that right about knee level on one of my shelves is a laser level I use to hang pictures and piss off the dog. So I took it out and fooled around to see if that gave me some idea of what was going on. I think it told me what I wanted to know:

These first four are slowly rotating the fretboard down from head to butt ("pitching"): I believe it shows that the fretboard gently slopes:





The next two--I was trying to figure out if the edges of the fretboards were straight. The one on the bass side (first two photos) looks pretty good ...




But on the treble side ... not so much:



What all of this tells me (if I read it right) that there is a dip in the neck right about frets 3, 4 and 5--which is where I thought I saw it. And it's possible that the neck is twisted, which might be why the laser shows up pretty straight on the bass side, but not the treble. The laser also showed me that the frets are all at different angles and heights as well.

At least, I think that's what it all shows me. If you think I'm misinterpreting, please let me know.

___
*"Brilliant" ... as in laser ...?

[the padma]

Yo, belbein,

Is called Relief...the dip in the neck right about frets 3, 4 and 5. The frets should then be level from the 6th to the end. Now days relief is put in the neck by adjusting the truss rod to prevent the "wider sine wave" created by the thicker strings when plucked, from buzzing on the fret board. In ages past this "dip" was tooled into the neck before adding the fret board by some builders or into the fret board by other builders. Then others just ignored it, went with a taller bridge/saddle and hence higher strings. NOw if your dip is on the bass side and not the treble, it sounds like the builder "tooled" this needed relief to prevent the thicker strings from buzzing.

To see if the neck is twisted, use winder sticks... actually any two sticks the same size will work.

To check for straightness of sides...use a machined rule or simply stretch a sting along each side of the fret board,from the nut, keeping it in tension as you bring the sting up to the other end of the fret board, in doing this you will see a gap between the string and the neck if it is bowed one way or you will see the string start to bend and confirm to the bulge if it is out the other way.

Regarding parallel frets, compasses, rule or calipers will reveal any out of parallel frets.


There are other ways me sure, but these are the methods me work with. Sorry me old school and don't fancy them there gadgets that cost money and piss off doggies.


Blessings
duh Padma