Neck... straight or slight bow? Warped versus unlevel frets?

Patience everyone... I'm just trying to learn. (There are no stupid questions, right?). I'm a player, not a tech. And I'm just getting into electric (been an acoustic bluegrass player most of my time).

I created some questions in the hope that the answers will help me to understand this aspect of the neck:
1.
Should a neck be TOTALLY straight, or should it have a slight bow in or slight bow out?
2.
When you lay the edge of a metal scale down the middle of your neck, should it meet all the frets from the 2nd fret all the way down to the 21st? (Variation on the above question.)
3.
I laid the metal edge of scale down my tele's neck to check it out. I can't see "daylight" between the fret surface and the metal scale (cuz not sure how to do that... need to have a colored paper background or something I guess) but I slid a sheet of paper between the metal edge and fret surface to find that... the sheet of paper slides freely from the 2nd fret all the way to the 18th fret. I assume this means that I have a bow in my neck that bows in. Am I correct on this? And if so, do I have a problem?
4.
How do I determine if is this a fret leveling situation as opposed to a warped neck situation?

Thanks in advance.
:?:

1.
Should a neck be TOTALLY straight, or should it have a slight bow in or slight bow out?The bow needs to be such that there is room for the string to rotate when plucked. Much like a bow and arrow and not opposite to that shape.

2.
When you lay the edge of a metal scale down the middle of your neck, should it meet all the frets from the 2nd fret all the way down to the 21st? (Variation on the above question.)I use a 2ft. straightedge from the first fret.

3.
I laid the metal edge of scale down my tele's neck to check it out. I can't see "daylight" between the fret surface and the metal scale (cuz not sure how to do that... need to have a colored paper background or something I guess) but I slid a sheet of paper between the metal edge and fret surface to find that... the sheet of paper slides freely from the 2nd fret all the way to the 18th fret. I assume this means that I have a bow in my neck that bows in. Am I correct on this? And if so, do I have a problem?After the strings are tuned. Put a capo at the 1st fret press the 6th string down at the last fret and with your other hand press the string at the 8th fret to see how close it is by looking at the movement of the string, (this is where I like a close clearance, a clearance of about approx .007"-.010" is sufficient. The eye can see .002" with some experience). Adjust this clearance by turning the truss rod nut in small increments 1/8 to 1/4 and check. Keep in mind you'll have to re-tune the strings and re-check clearance after turning the truss rod nut. Also the wood may still move a bit so many people will re-check again the next day.The last thing I do is set the nut slot height, which I like clearances at the 1st fret as close as possible so I take extra time with my guitars initially to find out where these clearances will end up expecting to replace a nut if I go too far with the file, although I never needed to yet. After all that if you have fret issues they will have surfaced and you'll need to get to work on the neck and frets or both.

with all guitars, there typically needs ..

... to be some measure of nut relief - you check that by fretting each string between the 2nd and 3rd frets, then look (there is no need to measure with tools, yer eyes are the best measuring devices in this case) at the space between the bottom of each string and the top of the first fret. there needs to be some light showing, if not, that could lead to open string buzzing. if any observed space is too large, making fretting and chording difficult, increase the nut slot depth. if there is no space, either drop fill (with bone or acrylic dust and water thin super glue) the slot(s) and recut to create nut relief.

... to be some measure of neck relief, primarily to allow for the excursion of the larger bass strings. check neck relief by fretting the large 'e' string at the first fret and somewhere around the 15th or 17th fret, then observe (do not waste time measuring with rulers and digital calipers!) the space between the bottom of that bass 'e' string and the top of, oh say the 6th or 7th fret. adjust the truss rod to create or remove neck relief.

the only need to stick a straight edge down the fingerboard, 'tween the 'd' and 'g' strings, is to check the neck angle on an acoustic (fixed bridge/saddle) guitar. other than that, if there are any unlevel frets, you will know that in short order (buzzing at specific frets)). 'playability' should be the #1 concern about any guitar, as dictated by the player's style and string attack, the string gauge and the scale length. work to achieve playability first and foremost.

you will know when the nut relief, neck relief and fret levelness are all correct - your fingers and ears will tell you that good news, profusely. :cool:

Listen to Rob.