Relationship between action and relief

Context: I'm an experienced player. Pretty fluent with routine guitar maintenance, and putting a few parts guitars together. I'm no luthier but I've learnt a lot over the years.

My question arises from some reading I'm doing for my next challenge - a refret on a surplus neck that Id like to use for a project.

I've been reading Hideo Kamimoto's "Electric Guitar Setups". Hideo has a table in his book which I find interesting, and dont quite understand fully. The table titled "Relief Calculations" appears to give relief measurements for each fret interval on a guitar neck. The relief measurements are in columns (Nut to Fret 12). There are then several rows in the table for relief at action increments of 64th inch. I've replicated the first few rows below...

Action (64s)	0 (Nut)	1	2	3	4	5	6	7	8	9	10	11	12
1.0	0.000	0.001	0.002	0.003	0.003	0.003	0.003	0.003	0.003	0.002	0.002	0.001	0.000
2.0	0.000	0.002	0.004	0.004	0.005	0.006	0.007	0.006	0.006	0.005	0.004	0.002	0.000
3.0	0.000	0.003	0.006	0.008	0.009	0.010	0.010	0.010	0.009	0.007	0.005	0.003	0.000

So the table implies that, for a guitar with 3/64 action (at 12 fret), you need to look for relief of 0.010 at 6 fret (fretted at 1 and 12 fret). I kinda understand that, what I don't understand is that....

(1) the table implies a that higher action would require greater relief
(2) That no relief should occur beyond fret 12.

Im confused. Esp as Fender and others recommend measuring relief at neck/body join. The higher action=more relief implication boggles my mind. :bonk

I wouldn't worry too much about it. Those are one man's calculations of ideal conditions that for the most part do not exist. Guitars have to endure different environments and will need to be adjusted differently. A guitar on an island with greater humidity year round will be set up differently from a guitar in a high latitude Scandinavian country that could be drastically drier for much of the year unless painstaking efforts are taken.

It seems counter intuitive, but I wonder if we're missing other factors.

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Originally Posted by DanTheBluesMan

I wouldn't worry too much about it. Those are one man's calculations of ideal conditions that for the most part do not exist. Guitars have to endure different environments and will need to be adjusted differently. A guitar on an island with greater humidity year round will be set up differently from a guitar in a high latitude Scandinavian country that could be drastically drier for much of the year unless painstaking efforts are taken.

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Thanks for the reply. Good point on the humidity.
I also was pondering that these numbers take no account of radius which surely would play a part.

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Originally Posted by Don

It seems counter intuitive, but I wonder if we're missing other factors.

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It does seem at odds with the philosophy of many who written on this subject. Where you should go by feel opposed to exact measurements.

I never measure. Simply straighten neck, lower strings as low as possible without buzz on upper frets. If buzz on lower frets 1-7 I add relief to just stop the buzz.

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Originally Posted by RyanUK

It does seem at odds with the philosophy of many who written on this subject. Where you should go by feel opposed to exact measurements.

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Measurements are a general rule that do not always fit each player so I am amazed that people go by measurements rather than set to individual preferences. Some people are light handed and don't bang the strings with a pick so they can get by using lower action while heavy handeness you will have to add some height to the strings

radius is a huge part of the equation as well. My 7.25 roadworn strat sets up way different from my clapton strat, and my Epi Dot, let alone the PRS I did the other day for a friend (12 maybe?)

If you have a high action you wont need much if any relief. If your action is really low you will need just a little relief to avoid buzz. Most truss rods only adjust relief from the third to the 15th fret. If you want low action and avoid buzz and fretting out on bends you do what is called a fall away of the frets, that is when each preceding fret is a little lower than the previous fret. You can do it buy crowning each fret one more pass the the one before it, or when you level the frets.