Question about string action gauge

Construction and repair of Classical Guitar and related instruments
LBrandt
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Re: Question about string action gauge

Post by LBrandt » Sun Jun 04, 2017 6:56 pm

bluesnik wrote:
Sun Jun 04, 2017 6:18 pm
I see what you mean. Then there's the issue that with this tool you are measuring from the top of the string rather than the bottom. Do you ever subtract the diameter of the string you are measuring from the digital readout to get a more accurate number?
No, the readout on the gauge IS the distance from the bottom of the string to the top of the fret. It may be counter-intuitive, but you do not subtract the string diameter.

bluesnik
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Re: Question about string action gauge

Post by bluesnik » Sun Jun 04, 2017 6:58 pm

You're right. Not sure how I didn't realize that!
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LBrandt
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Re: Question about string action gauge

Post by LBrandt » Sun Jun 04, 2017 7:17 pm

bluesnik wrote:
Sun Jun 04, 2017 6:58 pm
You're right. Not sure how I didn't realize that!
Yes, at first glance, it would seem that the diameter of the string has to be taken into account, but it doesn't. If it did, a gauge like that would not be of much use, since you would then have to know the exact diameter of both the 1st and 6th strings, and that could be a problem.

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petermc61
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Re: Question about string action gauge

Post by petermc61 » Mon Jun 05, 2017 6:18 am

LBrandt wrote:
Sun Jun 04, 2017 12:45 pm
petermc61 wrote:
Sun Jun 04, 2017 5:04 am
I fail to understand the comments about the string diameters affecting measurements. Could this be explained a little more clearly?
I'm only saying that with my lower action guitars, it seems that the gauge has a harder time sensing the smaller difference between the heights of the 1st and 6th strings. I'm not seeing this problem with the guitars that I have with higher action.
Still struggling to understand why. It simply measures string displacement from string at rest to the string down touching the fret. The measurement is the measurement. I don't think it 'senses' anything.....

LBrandt
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Re: Question about string action gauge

Post by LBrandt » Mon Jun 05, 2017 12:30 pm

petermc61 wrote:
Mon Jun 05, 2017 6:18 am
LBrandt wrote:
Sun Jun 04, 2017 12:45 pm
petermc61 wrote:
Sun Jun 04, 2017 5:04 am
I fail to understand the comments about the string diameters affecting measurements. Could this be explained a little more clearly?
I'm only saying that with my lower action guitars, it seems that the gauge has a harder time sensing the smaller difference between the heights of the 1st and 6th strings. I'm not seeing this problem with the guitars that I have with higher action.
Still struggling to understand why. It simply measures string displacement from string at rest to the string down touching the fret. The measurement is the measurement. I don't think it 'senses' anything.....
I'm getting better at using the gauge, and I guess that my first attempts were somewhat inaccurate. It's working fine now.

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petermc61
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Re: Question about string action gauge

Post by petermc61 » Mon Jun 05, 2017 12:42 pm

It's true you do need to not be heavy handed and to be careful when setting the initial zero point. Once you get used to that the readings should be pretty repeatable to within 0.02-0.03mm or so.

LBrandt
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Re: Question about string action gauge

Post by LBrandt » Mon Jun 05, 2017 1:40 pm

petermc61 wrote:
Mon Jun 05, 2017 12:42 pm
It's true you do need to not be heavy handed and to be careful when setting the initial zero point. Once you get used to that the readings should be pretty repeatable to within 0.02-0.03mm or so.
You are absolutely correct. After using the gauge for a while, I realize that you have to be very careful that the probe doesn't slightly move the string before you're ready to zero it and take the reading.

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bacsidoan
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Re: Question about string action gauge

Post by bacsidoan » Thu Jun 08, 2017 12:26 am

The LMI gauge comes in the mail today. It is flimsy and not very well made, but will do the job adequately. The zeroing process is not that easy with low tension strings because the weight of the plunger will depress the string which in turn will result in a falsely low reading. Perhaps I'm a klutz, but I find it not very easy to pull the plunger up until there's no string depression, while simultaneously holding the apparatus flat on the fret board and pressing the zeroing button. An easier way to get accurate measurement is to perform the zeroing process with the plunger resting on the string by its own weight. Next, pull the plunger up until there's no string deflection and note the negative reading. Add that amount to the final reading (when pressing the plunger until the string touches the fret wire) to give you an accurate and reproducible result.

LBrandt
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Re: Question about string action gauge

Post by LBrandt » Thu Jun 08, 2017 12:36 am

bacsidoan wrote:
Thu Jun 08, 2017 12:26 am
The LMI gauge comes in the mail today. It is flimsy and not very well made, but will do the job adequately. The zeroing process is not that easy with low tension strings because the weight of the plunger will depress the string which in turn will result in a falsely low reading. Perhaps I'm a klutz, but I find it not very easy to pull the plunger up until there's no string depression, while simultaneously holding the apparatus flat on the fret board and pressing the zeroing button. An easier way to get accurate measurement is to perform the zeroing process with the plunger resting on the string by its own weight. Next, pull the plunger up until there's no string deflection and note the negative reading. Add that amount to the final reading (when pressing the plunger until the string touches the fret wire) to give you an accurate and reproducible result.
You are right about the gauge. Today, I lowered my saddle using the Stew-Mac device (it works perfectly), and then remeasured the action using the LMI gauge. It is so lightweight that it is very difficult to hold it on the fretboard, get it set perfectly over the string and then zero it, before doing the measurement. I did it several times to make sure that I got a good reading. Your idea of using the negative is a good one.

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petermc61
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Re: Question about string action gauge

Post by petermc61 » Thu Jun 08, 2017 1:01 am

Not sure about all the trouble you guys are having. It seems pretty easy to me once you've done it a few times.

LBrandt
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Re: Question about string action gauge

Post by LBrandt » Thu Jun 08, 2017 1:30 am

petermc61 wrote:
Thu Jun 08, 2017 1:01 am
Not sure about all the trouble you guys are having. It seems pretty easy to me once you've done it a few times.
It's just a little difficult to get the probe to sit on the string without pushing it down ever so slightly, prior to zeroing it.

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