Official Luthiers Forum!

Does anyone have any experience with this tool?
http://www.stewmac.com/Luthier_Tools/To ... Gauge.html

This little device not only looked nice, and it made a lot of sense. But I couldn't see $60 for it. So I cut out a scrap of cocobolo to match the profile on the SM piece. But when I set the probe on the string, the plunger spring still causes roughly a .005" deflection downward before it stops on it's own. That's on the larger strings, I suppose it might be the same across the smaller gauge strings, I haven't tried it. But it takes a bit of fiddling to set the dial indicator in the block so that it touches the string without pushing it. Maybe that's the difference between my $15 indicator and the one supplied.

If the customer came in wanting a change you could easily use it in a relative sense. Measure the current height and if they want a lower action you could use it to take it down say .005" consistently across the nut.

I have to admit to some disappointment with how this thing works. I'd bet $20 I could measure the distance with my feeler gauges and magnifying visor on more accurately than this thing does. And doesn't Dan E. always say the measurements should be taken with the guitar in the playing position?

I think I wasted $15 and a some shop time.

open up the indicator and disconnect the spring from the plunger. Even with the magnifiers on I didn't detect any deflection with just the weight of the plunger on the string. Now it works like I expected. Nice $15 (I had a coupon) tool.

BTW, I did a real quick and dirty AutoCAD drawing of the block if anyone wants a copy.

Now you can even set it on the 12th fret. Zero it. Pull the plunger up until there is no tension and see how much that is. (approx .005") Then add that to the reading when you depress on either side of the fret. With the spring taken out of the equation, the motion is much more positive and readable. So with a little work, you can get the 12th also.

Hi Allen - The Stew-Mac offering is a really nice tool but we don't have it, use it, or likely want it and yes I actually did say that even when it's Stew-Mac.

In the last 6 years or so and after talking to thousands of customers I have yet to have a single client who proactively noticed and asked for the nut slots to be addressed.... For some reason nut slots seem to be something that customers are largely unaware that they may be struggling with high nut slots.... Go figure AND it's one of the very most noticeable and beneficial improvements that we can do to any guitar is improve the nut slot depth. F*ctories rarely if ever cut the nut slots as low as they should go because it's a skilled labor thing, more expensive to them and there is risk of one swipe with the nut file taking the nut too low. When you are Martin or G*bson and the nut has been finished in place cutting a nut slot too low can be a disaster....

We eyeball but we also have a special tool designed and made by Dave Collins that measures the exact depth of each, independent nut slot. It does not tell us exactly the height over the first fret but it will tell us definitively when we are triaging a guitar in for work with the client present if the nut slots need to be addressed. It can also quantify if slots are too low visually for a client to see and understand.

Anyway anything that we ever fancied thinking that we needed or could use we either get or make and this tool we don't have and haven't had a need for....yet.

Regarding playing position that's for action adjustments, fret work evaluation, etc. Nut slots are not going to change in any position since the span that we are really concerned with is the nut face to the crown of the first fret. Any ax that changes this little over an inch measurement in earnest when the position changes has to be made of rubber....

PS: This would be a good teaching aid AND it would be good for Geezers who can't see the little shift in light that .0005" of clearance represents when checking slots fretting and holding between the 2nd and 3rd. I can still see this little shift in light.... for now..... so I'm good....

I have one, use it nearly every day, and love it.

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It will probably be alright.

fumblefinger - very cool. I've been thinking about building one of these, as I have an extra dial gauge in the shop.

Hesh - would you mind sharing images and/or more details about the special Dave Collings tool you use? Its always interesting to see the myriad ways to measure something.

Sure, not the best photos because I had to take the shot and hold the stinking thing in place myself but you get the idea.

Dave Collins designed and made this some years back and it's what I use every single day. The bar is precision ground for flatness and registers on the first three fret crowns. The probe is narrow enough to fit in a very tight slot and that's all there is too it. We can see from one of the pics that the slot is .001ish" above the first fret crown.

Now a quiz for you guys..... Is it possible to have the dial read below 0 but still have the nut slot be ok in terms of not buzzing on the frets and why?

I've retired my stew mac gauge for this one:

http://www.lmii.com/products/tools-serv ... ight-gauge

Cheaper and more accurate readings.

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"I've been had again"
Tim Benware
Creedmoor, NC

The break angle of the string is actually a curve, so the string continues to climb away from the fret plane for some distance after the forward face of the nut. The amount depends on break angle, gauge and material of the string, and if it has been bent down from fretting close to the nut. That's how a nut slot could measure below the fret plane but still not buzz. Do I get an action figure or a belt buckle?

If I had to measure w/ a gauge between file strokes I might go insane.

12 strings? Mandolins? I'm working on a lute right now 19 strings!

I have old eyes. I use the StewMac gauge and like it. No need to measure with anything till you get almost done.

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Steve Smith
"Music is what feelings sound like"

BINGO!! Well done David!

I guess my thought was to use it to tell me what the current action is without playing the feeler gauge game. Also, say a customer wants his action lowered (I mean, how many have you had come in wanting it higher unless there is a problem?). I measure the current action, decide what we want/can do with it, lets say take it down .005. Measure the current nut slot depths, subtract the .005 and put that amount of feeler gauge up against the nut. When the nut file hits the feeler gauge I'll know that I've taken the .005 out of it without any guess work.

I agree feeler gauges would be hopelessly finicky measuring clearance over the first fret. Probably like many, I use a magnification visor when filing nut slots and find, if I squat down with my visor on, I can easily discern what stings are too high or low visually. If you fret the second fret, a .005" increment in clearance over the first would be huge. It's not often I find people complaining about an open buzz on the first fret until the clearance is pretty near zero. I think the stew Mac gauge might bee useful for calibrating what your eyes are seeing initially but I bet you could quickly do w/ out it after that. You do have to get your face right down there though.

Action although a function of nut slot depth should not be set with nut slots.... I know that this has been a point of contention on this forum before but regardless I am unaware of a single pro Luthier who does not cut nut slots as correctly as they can, also as low as they can, independent of any concerns about any target action.

The idea is that the slots are cut first, with the relief also set just before the slots are cut and this takes two of the three associated variables to setting action out of play letting the third variable, the saddle (s) be the final adjusting factor.

In other words the nut slots are cut correctly as low as possible first and independent of any other set-up concerns except one, the truss rod. Relief should be properly set or close prior to cutting nut slots.

If the player likes high action that's taken care of with the saddle - same for low action but the nut slots remain an independent thing AND one of the very most noticeable and valuable things to get right on any fretted instrument set-up.

Although nut slot depth invariably has a number that can be assigned to it what ever that number is matters little in the process because cutting the slots properly need not require any feeler gauges or any other measuring tools. We cut thousands of nut slots annually and only use measuring devices to triage an incoming instrument if a slot is suspected as being too low.

If I can see em at my age and cut them nice and low without magnification some of you younger dudes can too I'm sure. David F. don't know how old you are my friend but we could have a race to the bottom.... in terms of who goes blind first....

Well, I was already going blind once then had cataract surgery - almost a miraculous thing that was. Hesh, maybe when I'm up there this spring you can show me how you visually set the nut slot; ya never know, maybe I don't need no stinkin measurement tool

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Steve Smith
"Music is what feelings sound like"

Exactly, "nut slots are cut first". But how many nuts are what the customer needs/wants from the factory? Almost with out exception, when I talk to a player or read about someone having their baby made outstanding, nut work is one of the components of the fix.

I'm not making guitars, I'm trying to fix what the boys in China, Indonesia, where ever, threw together to get things out the door on schedule. Maybe I just haven't done enough setups to completely understand what it takes. When you've been doing this for 20+ years, I'm sure you can probably eye ball most things. For us newbies, we need something that will give us a measure of confidence. Accurate measurements are the only way I can do it, for now. When my eyeballs get more educated maybe I can dispense with all the measuring tools.

+1 on the cataract surgery. I didn't realize that I'd been looking through brown sunglasses for so many years!

Sheesh... I didn't know that you guys had cataracts..... I always preferred Lincoln Continentals.....


(sorry, couldn't resist.....

Steve sure, absolutely I am happy to show you how I cut nut slots and how it's possible that you too may not need magnification to get it right. I just turned 59, wear glasses an by no means have perfect vision.... an understatement but I can still see what I am looking for.

Allan then you have your work cut out for you in so much as the Asian instruments, North American too.... always come from the factory with very high nut slots. There are a few exceptions of course but most of the consumer stuff will greatly benefit from a complete set-up right out of the box. We have a client who is a dealer (not of Asian instruments) and our client has decided that his value add is to pass on the stuff that he sells after it has had a professional set-up so he pays us to set up the stuff that he sells. My hats off to him not just because he pays us.... but because he has recognized that he can have an "unfair competitive advantage" over his competition by providing more value with a very well set-up instrument out of the box.

Anyway I'm not sure if any measuring device that can quantify numbers for you is actually any easier than how we cut slots without any measuring device. For us it's as simple as looking for the presence or absence of a sliver of light and adjusting accordingly as the string diameter increases. There is a "tink" sound too that I'm fond of hearing that verifies for me that the string is not in direct contact with the fret crown.

We are the guys who measure fret boards for a long term fret spacing project so accurate measurements are super important to us too but again I'm not convinced that one has to know what the measurement of a nut slots is to cut a very well cut nut slot. If you can't see it that's a different issue though I'm sure.

I ‘m normally a science and numbers type who can't function w/out good tools. I don’t generally think its useful when some one interjects, “ I don’t need no stinkin’ expensive tool. I just gab an o’l tin can lid and thickness my tops til they feel right. Bin’ doin’ that way for 100 years.” But I think this is different. It's an unusual case in instrument work where it’s actually easier to do accurate work without a tool. Try it. Put a lamp on the far side, fret at the second and stick your face down there, and push on the string to see how much movement before it contacts the top of the first.
One thing that really slows down learning is having to stay on the safe side of things. If you’re ever replacing a nut anyway, file the slots on the old one lower and lower until they’re too low and watch as it happens. It will be worth more than 50 nuts cut without ever gong too low.

Depending on the height of the saddle and the scale length, the string can originate at the nut below the first fret and can still be able clear it without touching. Mathematically the string just clears the first fret when the nut is 0.02" below the first fret with 25" scale and 0.5" bridge height.

True that, great post David!

In addition to trying it when a nut has to be tossed anyway there are a few other things that help me.

For example the number of swipes with the file can be very helpful in not going too far. I often finish up a nut slot for the high e where I'm taking it as low as it can go and not buzz with only one swipe of the file and then I recheck.

Another thing that's important when cutting nut slots is if your technique may not be the best and that's how it usually is for builders since as a builder you only get to cut nut slots with each new creation it's a good idea to also work the string into the nut before checking. Sometimes sots are not cut as wide as they need to be and the string is not all the way down in the slot when we check resulting in a false read and making us cut more and there it goes.... the nut is ruined....

One other thing that I do is during that last swipe of the file I reduce the pressure on the file and/or if the nut material is very soft and easily roughed up by the nut file I switch to the older files that I save that are duller and do more burnishing than cutting.

I'm keen to cut a slot for the next larger gauge of strings too when it makes sense to do with an example being the client has 12's on the thing now so I want them to be able to struggle.... with 13's if they want without the instrument having to come back for nut slot adjustments. So I cut for the next size up.

If you use proper nut slot files and not an old string, welding rod, good intentions, or a hack saw blade.... and you feel the files binding try this - it helps me every single day. As you move the file down into the slot, and this really helps with new nuts that have not had the depth of the top of the nut reduced yet come in with the file at an angle sideways so that it scrapes one side of the slot on the way down. In other words we are enlarging the slot so that binding stops and we can go back to happily cutting our nuts..... correctly... This is also how I make my slots for the next larger string should that be something that the instrument has to deal with in the future.

What's wrong with the old string thing that some have posted that they do is that the string is not rigid so it's pretty easy to file a hump in the slot. If the nut face transition of the slot is not steep enough and instead pretty flat a vibrating wave can travel past the nut slot and into the slot before it terminates. This is the Norah Jones father's sound that we at times refer to a sitar sound. Files are rigid so the angle that we impart to the slot, for better or worse, is what we get. Not so much with an old, crusty string.

ICR true that and good answer as well. What I was looking for though is the phenomena that strings ark out of the nut face if rigid enough or because of drop tunings the tension is not as much as we typically see. The larger the string the more likely it is to do this and that's why a low e nut slot can read when measured with our tool too low but be fine when strung to tension.

Who knew that there was so very much to consider with a stinkin nut slot....

Here are some things to look for on your own stuff that is indicative of issues with the nut slots:

1) When tuning the pitch jumps and does not transition smoothly.

2) When tuning you hear a "tink" noise and the pitch also jumps.

Cause: Nut slot too tight

3) That ole sitar sound that Norah's Dad is famous for making....

4) The tuner will not settle down and the pitch read keeps changing...

Cause or possible cause the slot is cut at too shallow an angle OR the slot has a hump in the middle of it and the vibrating wave of the string is broaching the nut slot face and traveling into the slot. The other end of the "system" can cause some of this too if the saddle has been taken too low and the break angle sucks.

5) It's difficult to do an F bare chord or the instrument is difficult to play in the first several frets area.

Cause or one of them - nut slots too high and need to come down.

Next time we might want to talk about making nuts and/or materials suitable for nuts and why they work. Lots of cool stuff to learn and know too in that discussion from why some vintage stuff had ebony and even BRW nuts to why bone is such a great choice for nuts.

Well crap! Now I have to figure in a trip to Ann Arbor....

I'm guessing it'll be a better deal than the Stew-Mac gauge .

You fine folks are always welcome at our shop!

Sounds like it's time for a road trip Allan.

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Say what you do, Do what you say.

Well if we are gonna go North, we either need to be getting there or put it off till next spring. Unfortunately, my house mate has been very patient while I've been getting the shop in order and doing things to host the get together this Sunday. But she has let me know that after Sunday she has some "projects" that I better be attending to. Maybe we could plan a couple of us heading up that way next spring. Or if the get together takes off, pay Hesh or David's way down here...?

I have the StewMac gauge, use it all the time, love it. Quantitative data, I'm not much of a "well.....looks good to me" guy |)

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Blue Ring Acoustics
blueringacoustics.ca