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Hesh sincere thanks for your detailed thoughts on the spec I'm asking about as well as the broader issues relating to it.

It's very generous of you to offer consultation over the phone. But what I really need to do is take your course!

Traveling to you will be the biggest challenge for me but I hope to be able to do so at some point.

I've budgeted to attend the GAL convention this coming summer so adding more travel budget on top of that will difficult this year, but the value of what you're offering is obvious and David's intonation video has me absolutely sold as someone I dearly want to learn from.

Just to emphasize again, this whole adjustable nut obsession is just for instruments I'm making for myself. I don't want to force it on anyone else in a repair/setup context.

I have no doubt that the vast vast majority of acoustic players absolutely agree with you!

It would be a longer trip for you then it was for me but given the degree of thought that you have obviously invested into this idea I can tell you that you would be very happy that you took the course. Dave and Hesh will feed you all the knowledge that you can handle and the more you know when you show up, the more you will learn. Some of the best money I've spent in the guitar world!

_________________
Steve Smith
"Music is what feelings sound like"

To me.... I see 2 general adjustment scenarios.

1. The initial setup - where you file until you home in on the "right" setup within a very close tolerance - say +\- 0.002". That part is going to start with blanks and is still going to require files and such.

2. Ongoing tweaking - this is where you use the itty bitty screw to move it up or down 0.0005" to 0.001" at a time to home in on "perfect"....

So.... I would give someone blank inserts which have the capacity to be adjusted from 0" to -0.150" or so... This allows flexibility for fretboard and fret heights, nut pocket depths, and such....

But the actual jacking mechanism..... I would do +\- 0.005" or +\- 0.010" total adjustment. This will allow sufficiently fine adjustment to do 0.0005" adjustments without breathing and overshooting by 10x that..... So say threads with 100 threads per inch. 1/2 turn = 0.005" push on a tapered 10:1 wedge that nets 0.0005"... The total available adjustment is +\- 5 full turns. Rather than 20 threads/inch where 0.0005" = 1/100th of a turn. Or basically impossible to achieve truly fine tuning.

Say your entire mechanism is 0.150" tall.... Say your threaded section is 0.100" long. 100 threads per inch = 10 threads. 20 tpi = 2 turns. Yours looks more like 50 turns.... Which makes 500 tpi... Or 0.002" per thread. Will your equipment do this?


Thanks

Assuming this is for personal use only, let me ask this question:

Do you anticipate wanting to be able to adjust the string height at the nut and nut compensation on an ongoing basis (let's call this "dynamic"), or do you just want something to help you create a "static" perfect nut that will not need adjustment for a very long time?

If you anticipate wanting to make lots of little adjustments over time, then this is a worthwhile and interesting endeavor. I personally don't see this need for my own guitars; I want to set the nut and not adjust it (meaning replace, sometimes) until much later in the life of the guitar. But if you see this need, have at it.

If, on the other hand, this is a means to making a great "static" nut, it feels to me like you are over engineering something in order to make up for not learning the skill of creating a great "static" nut out of bone. I think a more direct path to what you want is learning the skill.

Hey Leo don't get me wrong my hat is off to you for thinking outside the box and wanting to take things to a different level. That's notable and if someone didn't do that hundreds of years ago we would not have any guitars to have GAS, guitar acquisition syndrome over...

I wanted to give you a few more considerations that before I started doing high volume, high quality repair work in a very busy commercial shop I would have never considered.

Some nuts are finished in on the guitar. This means that the finish has been sprayed or other methods of application after the nut was installed. Martin is known to do this, G*bson too and even Guild at times. It's a nice look although not all that serviceable because to remove the nut you need to score the finish and hope to hell that this was not one of the vintages where nitro would flake off like nobodies business....

With these guitars and some even have an iv*ry nut from back in the days before Martin stopped using iv*ry keeping the existing nut in place might be desirable and prudent.

So what's the fix? We all know about bone dust and CA, pack it in there, recut, and have a fix that might last 6 months before someone is complaining that their open string is buzzing again....

For these nuts we won't remove and if appropriate for the instrument may fill but with light cured dental fillings. Dental fillings are as hard or harder than bone, WAY harder than CA and bone dust, and are very much an upgrade over the next best thing, a well made bone nut.

Our introduction to the idea came from Frank Ford years ago, thanks Frank!

What this highlights is that a low nut slot can be repaired and even augmented to be better than new in the hardness and longevity sense. We are considering offering this as an option and not just a repair method.

This technique also provides new nut slot cutters with a way forward short of replacing a nut when one cuts too low.

Or in other words there is a current fix that works very well for a low nut slot without replacing the nut.

Some more food for thought. Nut slots can be well cut and then forgotten. Yep, it's not something that needs periodic adjustment. Although the string height in the nut slots is a function of action height it's not where we adjust action. Some will but most that I know view nuts slots as being very well cut for player comfort AND to prevent strings from being pulled sharp because a high nut slot requires more bending of the string to fret. We also find that with very well cut nut slots nut compensation is not required..... Although action height is a function of nut slots, relief, and saddle(s) height most Luthiers that I know will cut the nuts slots first and take that variable out of play.

Think about what I just shared. For those who struggle with set-ups or just are not sure that they are doing things in a sequential order that works well cutting the nut slots first after setting relief and tuning to pitch takes two of three variables for action adjustments completely out of play. That's a good thing. Then action is set at the saddle(s).

You can see that in my world and with the approach that I take to setting up an instrument adjustable nut slots would not do a thing for me or my clients. Even with a slot that is too low we have a fix that is long lasting, easy to do, tonally unnoticeable, and lets us play dentist when we want to....

Also again for instruments where there is some risk of cosmetic blemishes by removing the nut or it's a vintage instrument and keeping it whole is important we have a fix with filling with dental fillings for that too.

No offense intended and I was a builder and kind of sort of still am but with dust allergies but we builders tend to neglect the idea that a guitar is not just a woodworking project or just another pretty piece of wood. Guitars are tools for musicians and as such your set-ups will make or break any impression of your creations.

Hope something here helps and again my hats off to you for not just accepting what is but looking for what could be better!

Also it might be helpful to you and others to start a thread about how to cut nut slots and I am sure that folks will be happy to help.

Hesh I have only just picked up on this thread,

As a beginner I would welcome your thoughts on nut slotting, as I imagine would other members of this forum. I take your point entirely that with very low action at the first fret that nut compensation becomes less important. However the whole system needs to be addressed: neck angle, bridge height etc.

I would welcome your thoughts on this whole system approach as an experienced builder

Cheers Dave

You are absolutely correct that a system approach is warranted in so much as much of this is a function of something else.

Because the subject is huge what would be easier at least for me is to distill the conversation to specific aspects. For some of the related concerns of the system... see my toots in the toot section and specifically the "neck angle" and "fitting a neck" toots.

Assuming that the neck angle is correct, scale length measured and implemented correctly we can then talk about the nut slots in isolation and/or how they relate to a set-up.

There are also some very good threads with some rather heated disagreements about the merits of cutting slots with V shaped files, or not..... and what kind of files some of us use. You can find these threads with search keys of "nut slots", "nut files" etc.

There are lots of nuggets of good info in these threads such as how to enlarge a nut slot by scraping the sides with the file on the down stroke or how to use fingers as registration guides for getting that approx 7 degree angle on 14 degree set-back headstocks.

I'm happy to address specific questions as best that I can but again the subject is huge so much so that we offer full day classes in nut making and set-up. As such if you want to limit the discussion to something specific it would be appreciated and I'm all in.