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I am new at this but a long time player now looking to invest in some tools and set up shop.



So I see that there are various methods to leveling frets but what I'd like to know is what is the correct curve for a neck?



Some neck guages measure at the 5th fret some around the 7th, while others use a staight edge and feeler gauges but this all leaves me confused.



Should the neck have a perfect arc to it or should it be more parabolic towards the nut?



I see products like the Katana for fret levelling and although info is limited on the device, it looks like it bows evenly when the knob is tightened.



So this should leave a perfect arc on the neck but is this correct?



Seems to me all my guitars seem to have more curve down at the nut than further up the neck so obviously this is not a perfect arc but more of a parabola but which right?



Has anyone ever studied guitar string motion?

For guitars with adjustable truss rods I want the frets dead level to start off with. I will use the rod to set the relief. I may add a bit of fall off on the FB extension of an acoustic, something like .007".

For guitars without adjustable rods like older martins I support the neck at the and place 10 lbs. (actually 2 kilos) of weight on the shoulders of the guitar. This usually yields proper relief when strung.

If you do some internet searches you will find more than a few studies of string vibrational motion, nodes etc.

_________________
Brian

You never know what you are capable of until you actually try.

https://www.howardguitarsdelaware.com/

All of us who work on guitars agree that they need some relief, we just don't always agree how much or how to get it. Relief works in conjunction with saddle height to provide enough clearance for the vibrating string to not hit the next frets, while still being close enough for easy play. Whether this is an arc, a parabola or some other curve really doesn't matter - we are talking about a few thousands of an inch over a 14 or so inch length of fretboard. And yes, there have been some very deep studies made of the envelope of a vibrating string - but again, I'm not sure how you use that information.

My very simple procedure is basically as follows. When a guitar comes to me I measure everything - I have a little spreadsheet and it only takes 5 or 10 minutes to record it as found. If possible I ask the owner to play it for me, I like to observe technique and listen to his/her comments. One thing I learned recently is confirm the string gauges on it - sometimes the owner doesn't know what they are playing LOL.

Next I take the strings off and adjust the fretboard perfectly flat, then do the frets. There is no point in doing any other setup work until the frets are perfect - whatever method you use do it now. Then I restring it and measure the relief - I use the simple method of a capo on the first fret, hold the string down on the neck to body fret (usually 14 on an acoustic, 16 or so on an electric) and measure the string to fret clearance half way in between (6 and 7 for an acoustic, 7 and 8 on an electric). All I look for at the other frets is a nice increase in clearance from each end.

I'll adjust the truss rod to try to get to a target relief - for me that is somewhere around 0.004-5 for an acoustic, maybe 0.002-4 for an electric. Next the nut, and finally the bridge/saddle height. What I like to do while I set the saddle is to play each fret checking the clearance to the next one - I want to be able to tap the string over the fret and feel about the same clearance and here a little "ping".

A troublesome spot often occurs at the neck to body joint. Relief stops at that point, the fretboard extension is often flat and may drop off towards the bridge. That usually isn't a problem for a bluegrasser who only plays cowboy chords, but it can be a big problem for an electric player with slinky strings and very low action. Sometimes those frets need a little extra care to get what the customer wants.

When I am all done I remeasure the guitar and fill out another column in my spreadsheet - it also has a column of target values. The customer gets a copy.

Different players and different tech have very different target values - here is an interesting look at guitars of the stars (I don't think I would like playing SRV's guitar)

http://www.stewmac.com/How-To/Online_Re ... itars.html

And if you want to wade thru 3 pages of practical information about relief, this is a pretty good start

http://www.bryankimsey.com/setup/neck_relief_1.htm