Question about string action gauge

Construction and repair of Classical Guitar and related instruments
LBrandt
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Joined: Sat Mar 26, 2011 1:40 am

Question about string action gauge

Post by LBrandt » Sat Jun 03, 2017 8:57 pm

Hello,

I've just purchased the LMI string action gauge. Have any of you used this gauge, and if so, do you like it and feel that it is accurate?

For some reason, on a couple of my guitars, I'm getting higher readings on the 1st string than I am on the 6th string (just backwards from what it is), and I know that the action on the 1st string is lower than the 6th.

Louis

bluesnik
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Joined: Thu Nov 13, 2014 11:02 am

Re: Question about string action gauge

Post by bluesnik » Sun Jun 04, 2017 12:19 am

I purchased this a few weeks ago. I feel it is pretty accurate. (I trust it more than my weakening eyes with a stainless steel rule). My concern was that as you position the 'plunger' on the string it pushes it down slightly before your press it to the fret to take the measurement. Since you are supposed to measure from the 'bottom' of the string to the top of the fret, I was wondering if the amount the string gets pushed down was compensating for the fact that you are on the 'top' of the string. I doubt however that it would be able to distinguish between the diameter of a Low E and a High E string.
2014 Ramirez 'Conservatorio' CD/IN
1975 Ramirez 1a Classical CD/BR
1976 Ramirez 1a Flamenco CD/CY

bluesnik
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Re: Question about string action gauge

Post by bluesnik » Sun Jun 04, 2017 12:22 am

Just to follow up on your observation about the higher reading on the 1st string, I've not experienced this. The 1st string always reads about 1mm lower than the 6th string on all my guitars.
2014 Ramirez 'Conservatorio' CD/IN
1975 Ramirez 1a Classical CD/BR
1976 Ramirez 1a Flamenco CD/CY

LBrandt
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Joined: Sat Mar 26, 2011 1:40 am

Re: Question about string action gauge

Post by LBrandt » Sun Jun 04, 2017 12:55 am

As a follow-up, after taking more readings, my conclusion is this: On guitars with higher action, the gauge is more easily able to distinguish the height difference between the 1st and 6th strings, but on guitars with lower action, the smaller difference in the two heights makes it harder for the gauge to distinguish that smaller difference.

I saw a video of another gauge sold by Stew-Mac that looks similar to a round-dial tire gauge, but I couldn't find that gauge on their site.

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petermc61
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Re: Question about string action gauge

Post by petermc61 » 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?

OldPotter
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Re: Question about string action gauge

Post by OldPotter » Sun Jun 04, 2017 6:36 am

I saw a video of another gauge sold by Stew-Mac that looks similar to a round-dial tire gauge, but I couldn't find that gauge on their site.
They call it a nut slotting gauge. I think they missed a point with it, in that it could have been used as an action gauge too. The only problem is the dial gauge which has a return spring to retract the probe. So not easy to let it just rest on the string. Its a bit expensive.
"When I was younger, I could remember almost everything, whether it happened or not." Mark Twain

LBrandt
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Re: Question about string action gauge

Post by LBrandt » 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.

LBrandt
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Re: Question about string action gauge

Post by LBrandt » Sun Jun 04, 2017 12:52 pm

OldPotter wrote:
Sun Jun 04, 2017 6:36 am
I saw a video of another gauge sold by Stew-Mac that looks similar to a round-dial tire gauge, but I couldn't find that gauge on their site.
They call it a nut slotting gauge. I think they missed a point with it, in that it could have been used as an action gauge too. The only problem is the dial gauge which has a return spring to retract the probe. So not easy to let it just rest on the string. Its a bit expensive.
Have you used it? Even though it's not easy to use, is it accurate?

bluesnik
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Re: Question about string action gauge

Post by bluesnik » Sun Jun 04, 2017 1:00 pm

Stew Mac doesn't recommend the 'nut slotting gauge' for measuring action at the 12th fret. Here's what they have to say about it: " Your most accurate measurement is at the first fret. Although this tool can be placed at other points along the neck, we recommend using it at the first fret for maximum accuracy. The proximity to the nut keeps the string rigid at the first fret, and gives the most accurate reading. As you move up the neck (the 12th fret, for example), the string is much less rigid. Even the weight of the dial indicator's plunger is enough to push the string down, giving a false reading." This is my concern with the LMI tool that I own. The plunger resting on top of the string will push it down slightly.
2014 Ramirez 'Conservatorio' CD/IN
1975 Ramirez 1a Classical CD/BR
1976 Ramirez 1a Flamenco CD/CY

OldPotter
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Location: Channel Islands

Re: Question about string action gauge

Post by OldPotter » Sun Jun 04, 2017 1:25 pm

Have you used it? Even though it's not easy to use, is it accurate?
I made my own copy with a cheap dial indicator, to use as an action gauge, not a nut slotting gauge. I haven't perfected it, but the potential to be very accurate and very easy to use, is there. I removed the return spring from the dial indicator, so it also rests heavily on the string, under gravity. It wouldn't take much to balance the weight of the probe with another lighter spring. It takes careful observation to see when the probe first touches the string. If the indicator is used on its side then gravity doesn't affect the reading at all. A cheap dial indicator is still very accurate and easy to read.
I think the best value for money is still the tapered ruler, like a bore gauge.
"When I was younger, I could remember almost everything, whether it happened or not." Mark Twain

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geoff-bristol
Amateur luthier
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Re: Question about string action gauge

Post by geoff-bristol » Sun Jun 04, 2017 1:59 pm

I check string heights now with a small slip of wood packer - just lower than the string height. Then - slip in feeler guages on top until you can 'hear' it rub the string base. Then take the packer and the guage out and measure with a digital caliper.
Easy - cheap !

LBrandt
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Re: Question about string action gauge

Post by LBrandt » Sun Jun 04, 2017 5:27 pm

To follow-up my original post on the LMI action gauge, after working with it a little more, I find that it does perform very well. It just took a little time to get used to it.

bluesnik
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Re: Question about string action gauge

Post by bluesnik » Sun Jun 04, 2017 5:32 pm

Hey LBrandt, you don't feel like the weight of the plunger pushes the string down before you press it to the fret to take the measurement? This is my only concern.
2014 Ramirez 'Conservatorio' CD/IN
1975 Ramirez 1a Classical CD/BR
1976 Ramirez 1a Flamenco CD/CY

LBrandt
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Joined: Sat Mar 26, 2011 1:40 am

Re: Question about string action gauge

Post by LBrandt » Sun Jun 04, 2017 6:06 pm

bluesnik wrote:
Sun Jun 04, 2017 5:32 pm
Hey LBrandt, you don't feel like the weight of the plunger pushes the string down before you press it to the fret to take the measurement? This is my only concern.
Yes, as a matter of fact, I do feel that way! You have to be extremely careful to keep the weight of the plunger from pushing on the string just a bit, before you actually push it down to take the measurement. You almost have to lift it just a hair, so that it doesn't exert any downward pressure before you're ready to use it.

bluesnik
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Joined: Thu Nov 13, 2014 11:02 am

Re: Question about string action gauge

Post by bluesnik » 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?
2014 Ramirez 'Conservatorio' CD/IN
1975 Ramirez 1a Classical CD/BR
1976 Ramirez 1a Flamenco CD/CY

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