Official Luthiers Forum!

I know many experienced luthiers prefer to simply use their eye, and experience when adjusting things like neck relief and nut slot height. But for those who do use feeler guages I was wondering if you'd be willing to pass on some tips for best technique in three cases specifically.

When measuring relief, do you look for absolute clearance? The feeler guage doesn't touch the string at all when passing between the bottom of the string and the top of the fret, or do you look for the feeler guage to meet significant resistance moving between that slot. I find there is usually a stretch of a few thou between where the guage freely moves, and where it finds significant resistance, this is complicated again by the angle I come at the string, I aim for consistency, but... For instance if .006 clears easily usually .007 - .009 will clear but touch ever so slightlty before maybe .010 obviously finds resistance in the gap. Would you call this relief of .006 or .010, somewhere in between?

Secondly, I find measuring the High e and Low e with a feeler guage at the nut to be easy, but it gets more complicated when trying to measure the inside strings. I've been lifting the outside strings up while measuring the middle ones, but I'm concerned that the added tension of lifting a string might be skewing the measurements.

Finally, do you measure in playing position. or laying flat on the bench. Flat on the bench is easier, but I do notice a difference in measurements between the two.

Finally, I realize that consistency in personal approach is the most important thing, if one does things the same way every time, and the results are satisfactory it doesn't really matter what the measurements are, or how a person reads the measuring devices. But I'm not quite there yet...

You are overthinking this. A feeler gauge fits at gap or it doesn't. It should be a snug but easy fit to the gap.

I judge relief with my calibrated eyeballs.

Barry is right on except that I judge relief with feeler gauges. You can feel with the gauge is contacting the string or fret, you can try rocking it slightly, you can very lightly press the string down to see if it moves or the feeler gets tighter. Frankly a couple of thousands doesn't matter.

(It probably helps that I grew up with car engines that actually needed to have spark plugs and breaker point gaps set as part of tuning them)

I’m SOOO with you on the spark plugs!


Pierre

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Pierre Castonguay

But sparkplugs don't flex like guitar strings...

I use feeler gauges for measuring relief. Because the strings do flex, I look for movement of the string as I slide the gauge between it and the fret. The thickest gauge I can get in the gap without moving the string is the what I consider as the relief. I do this with the guitar on my workbench, not in a playing position. I use a small spacer to lift the outer strings a hair as I measure the inner strings. I haven't found that negligible amount of added tension to create any problems.

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George :-)

Breaker points were every bit as troublesome as strings to me...


Pierre

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Pierre Castonguay

I don't use strings to measure relief but an 18" machinest's straight edge. This gives much better accuracy when using either eyeballs or feeler gauges. And you don't have to deal with the flex of the string.

And valve lifters......

Not picking on George, or anybody else......but Is .0005 really that big a deal as far as neck relief? The local shredders want super low actions, with light gauge strings, necks are almost flat .002/.003 relief. To their credit they have developed a very light touch. Most necks have a sweet spot where they just start to work, I set relief where I think is best do the set up and play the guitar, if its good your done or you can try a minimum truss rod adjustment either way to get the perfect setup

The use of feeler gauges is simple. It is the measure of a gap between 2 surfaces. If you meet resistance, it means that something is being moved out of the way ..... you have changed the gap. So no resistance. Just make sure that the blades are level/aligned to the surfaces you are measuring.

Using feeler gauges to measure relief has always annoyed me and I feel like I can't get it perfect. My best work usually comes from eyeballing relief and nut slot depth, but I would like to be able to measure.

Do any pros use those relief dial gauges for these two tasks? I remember before a few people swear by them. But I haven't heard much lately.

I used to eyeball or roughly measure my action at the 12th, but after I got the stewmac gauge my results and consistency went way up. Not to mention speed.

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Pat

Yes, the dial gauge from StewMac will let you measure relief - be careful with it, you can get bogus results if you're not. I initially used a dial gauge when I started really trying to get nuts dialed in properly. After a while you get to where you can tell by just looking at it using a bright light or just listen to the "tink" sound when you tap the string with a finger against the fret. I have used feeler gauges to measure relief but in an earlier life I was an aircraft mechanic and we had to measure everything so I got a lot of practice; regardless, measuring relief with feeler gauges is a PITA. I pretty much do what Clnchriver is doing but I get there with the "tink" method.

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Steve Smith
"Music is what feelings sound like"

I understand that highly experienced techs/builders can eyeball things with remarkable accuracy. I'm getting closer to that level all the time, but I'm not there yet. I use feeler gauges (and a long straight edge) to educate myself and not because I think .0005 is going to make a noticeable difference--at least not to most people.

I use the "tink" method at the nut.

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George :-)

This will sound like bragging.... My industrial training was as a tool & die maker, a multi-skilled machinist. We were trained to check for minute variations in machined cuts by dragging our fingernails across the surface (we turned our fingers upside down so as not to apply pressure and fool ourselves). Years of practice meant I could usually tell how many thousandths the variation in surface might be. I could usually tell right down to about .003 - slightly thinner than a piece of paper. Eventually, I could look closely and guess within a couple thousandths. I worked as a lead man for in a production shop helping keep the work on track, and the operators referred to me as "Ol' Calibrated Eyeballs". I would advise them to drop or raise a tool by so many thousandths, and they would check me with precision tools.... I was pretty dependable. Of course, wood is not as dimensionally stable as most metals, and that lack of precision sometimes drives me crazy.

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"Act your age, not your shoe size" - Prince

Bragging or not, it sounds very cool. I would like to have calibrated eyeballs.


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