How to check fretboard/neck straightness?

[kalapoka]

hey everyone,

I've recently changed the strings for my DK2M after a long time, and I am not really good at all that setup stuff, so I have a suspicion that my fretboard might have warped a bit. How do I check this for sure? I want to make sure about a very straight neck/board and very low action becuz I have some problems with the skin of my fretting hand, and I can't set the action higher. I can't put excessive pressure on my fretting fingers, and a warped board forces me to do that. How do I make sure that I have a straight board? I am looking for mechanical/technical answers and not just by looking at it or feeling for it.

can anybody help?

[Tommie]

First of all warped is when the neck has more bow in it at the top E string than the bottom or vice versa - I.e. The neck would be twisted. That's rare, unlikely, would not be caused by you changing the strings clumsily and is a specialist job to fix. I don't believe your neck will be warped. I assume you're referring to whether the neck is straight or has a bow (concave curve) in it? That is easy to measure, as your strings make a perfect straight edge. Press the high e down at the first and last frets and see if there is a gap between the string and the 7th fret area. If there is, then you have some bow. A small amount is necessary otherwise you will find more fretbuzz at the lower frets than the upper ones, and/or the action will feel stiff at the upper frets. Why is this? When you fret a note, the string takes off the fret at a slight angle, as it has to clear the next fret. If you fret the string at thx next fret up, the angle is very slightly higher, and so on up the neck. If the neck is set with a very slight concave bow, you can eliminate that difference in angle so the clearance is consistent along the whole neck, making for lowest, most consistent action possible. There a little bit more involved than just the factor I noted, such as the fact a string vibrates in a elliptical fashion, but that's the physics and geometry involved, and I hope it helps to understand that.

[DonP]

You can use your strings as a straightedge by putting a capo at the top and bottom of the neck. Then measure the gap between the strings and frets.

Sound like what you really need is Dan Erlewine's books. Google it.

[JACKSONFREAK]

Press the string down at the first and last frets as mentioned above. You should have a slight bit of relief. I usually say about the thickness of a business card between the 5th to 7th frets. If there is no space bewtween the frets yo need to adjust the truss rod towards the high e string to put som erelief in it. Only about a 1/4 turn should do it. I usually set action at .060 at the twelfth fret on the low e and a bit lower like .055 on the high e. Adjust from there for playing style. Hope that helps.
Gil

[straycat]

For the fretboard to be warped that would mean the whole neck is twisted and that is very unlikely.In the last 20 years I have only seen 2 maple necks do that.
I've done tons of repairs and set ups and only seen 2 I doubt yours is out of whack.

[kalapoka]

I every one, sorry for the confusion I created mentioning 'warp' as I didn't know the correct term for it. You are right, I am afraid of the 'bow' and not 'warp' and all of your answers really helped. One more thing - when I press down on top fret and the last, on which string should I measure the distance from the frets? 6th or 1st? and How much gap is a good low action gap for the jackson dinky neck? i am using Ernie Balls 09-42s.

Lastly, I guess it's not really possible to have a very straight neck like shawn lane's vigiers on standard guitar necks? I am after lowest of low actions only because of the conditions of my fingers. I am having to compromise quite a bit of 'tone' for this - but I guess I'd like to continue playing for a long time and any action higher than my comfort zone just rips the skin of my fingers apart . What a curse for a guitarist!

[MetalMedal II]

As mentioned twice above, strings under tension are built in straight edges. Though it is easier to see the relief under the low e than the high e just cos it's so damn thin.

[Tommie]

You should be able to get the neck dead straight on any guitar, it's not a characteristic that's reserved for some fancy Shawn Lane thing. Just tighten the trussrod a tiny amount at a time until there is no gap at all between strings and frets when you hold down the string at highest and lowest frets simultaneously as suggested earlier. You might like the guitar like that, but in my experience you'll find that the strings will buzz excessively on chord work down the lower frets, plus the action when playing high up the neck will feel like it's too high by comparison. Best thing is to try it and see what you prefer.