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Desired range of action adjustment at the nut?
http://luthiersforum.com/forum/viewtopic.php?f=10101&t=48673		 Page 1 of 2
Author:  Durero [ Sun Dec 11, 2016 8:13 pm ]
Post subject:  Desired range of action adjustment at the nut?
I'd like to pose a design question to the community:

If you imagine a nut which had a height adjustment mechanism built into it, what would be your desired range of adjustment?

I've own a Chapman Stick-bass for years and Emmet Chapman has long had a very simple height adjustment mechanism at the nut where each string sits at the top of a modified stainless steel screw which can be adjusted up and down.

I'm trying to design a mechanism which functions more like a tune-o-matic-style bridge, except at the nut.

I have an incessant fantasy of simply adjusting the nut to a buzz-free height, instead of painstakingly filing nut slots and starting over when I've gone too deep gaah


What do you think? Would a 1/16" of height adjustment range be plenty on a custom built instrument? I'm not aiming for a retrofit-able design.

Leo
Author:  Chris Pile [ Sun Dec 11, 2016 8:23 pm ]
Post subject:  Re: Desired range of action adjustment at the nut?
You are aware that this has already been done by several makers and aftermarket producers already?
Author:  kencierp [ Sun Dec 11, 2016 8:34 pm ]
Post subject:  Re: Desired range of action adjustment at the nut?
As Chris mentioned several versions of such a devce already available, most notably Gibson's.
Author:  meddlingfool [ Sun Dec 11, 2016 10:59 pm ]
Post subject:  Re: Desired range of action adjustment at the nut?
I don't want to adjust string height at the nut. I want it to be right, and only right, at all times.
Author:  kencierp [ Sun Dec 11, 2016 11:17 pm ]
Post subject:  Re: Desired range of action adjustment at the nut?
viewtopic.php?f=10101&t=48259&hilit=Gibson+zero+fret+adjustable+nut
Author:  Chris Pile [ Mon Dec 12, 2016 12:53 am ]
Post subject:  Re: Desired range of action adjustment at the nut?
Alembic used to do this back in the late 70's....

http://www.guitarpartsresource.com/BN0887008.jpg
Author:  Colin North [ Mon Dec 12, 2016 7:27 am ]
Post subject:  Re: Desired range of action adjustment at the nut?
All very well having a nut with height adjustment mechanism built into it.
But unless you have individual adjustment for each string, you're going to have to cut or form the relative heights of the nut slots to each other to meet your desired string heights at the nut.
Then you're back to "filing nut slots and starting over when I've gone too deep gaah"
Author:  jfmckenna [ Mon Dec 12, 2016 9:48 am ]
Post subject:  Re: Desired range of action adjustment at the nut?
For what reason would you want to be able to adjust the string height at the nut? The fore-aft for intonation yes maybe...
Author:  SteveSmith [ Mon Dec 12, 2016 10:21 am ]
Post subject:  Re: Desired range of action adjustment at the nut?
jfmckenna wrote:
For what reason would you want to be able to adjust the string height at the nut? The fore-aft for intonation yes maybe...


I think he's just trying to avoid the "oh crap, I cut that slot too deep" moment we've all enjoyed at one time or another.
Author:  david farmer [ Mon Dec 12, 2016 12:12 pm ]
Post subject:  Re: Desired range of action adjustment at the nut?
.040"-.060" to cover from frets filed down to new tall ones. Plus .030"-.060" to accommodate planing off the end of the fingerboard to fix neck angle and/or excess relief. (Note to builders: break angle should work through this range as well)
So, 1/8" range, adjustable with increments of .0005" or less should do it.

Making a bone nut sounds easier. But let us know what you come up with.
Author:  Durero [ Mon Dec 12, 2016 4:54 pm ]
Post subject:  Re: Desired range of action adjustment at the nut?
Thanks to all of you for your responses, they are much appreciated.

Thanks David Farmer for actually throwing in a number, that's all I intended to ask for but not surprisingly I've gotten more than I asked for.
Author:  Durero [ Mon Dec 12, 2016 5:10 pm ]
Post subject:  Re: Desired range of action adjustment at the nut?
Colin North wrote:
All very well having a nut with height adjustment mechanism built into it.
But unless you have individual adjustment for each string, you're going to have to cut or form the relative heights of the nut slots to each other to meet your desired string heights at the nut.
Then you're back to "filing nut slots and starting over when I've gone too deep gaah"


Thanks Colin this is an excellent point. I've been going back and forth in my mind about whether I can get away with height adjustment for the whole nut or whether individual string height adjustment is needed.

The discussion in the thread that Ken linked to (thanks Ken!) has some fantastic posts by David Collins which make it clear that individual string height adjustment is a significant advantage and makes it possible to address differing break angles and their affect on string height over the first fret.
Author:  Durero [ Mon Dec 12, 2016 5:57 pm ]
Post subject:  Re: Desired range of action adjustment at the nut?
jfmckenna wrote:
For what reason would you want to be able to adjust the string height at the nut? The fore-aft for intonation yes maybe...


The fore-aft adjustment for intonation is actually a higher priority for me than the height adjustment, but I'm working for a design which can do both.

I've already settled on an intonation adjustment spec which I'm happy with which I've taken from the work of Gary Magliari's intonation article in AL#116, Mark French's intonation article in AL #125, and the Gore/Gillet books.

I've sketched out a couple of designs in CAD before, but after considering the individual string height issue I'll have to keep trying if I hope to find a design that can reach the precision level possible with traditionally made nuts.

Attachment:
Leo Classical Nut 1.jpeg


Attachment:
Leo Adjustable Nut version 2.jpeg
Author:  david farmer [ Mon Dec 12, 2016 6:49 pm ]
Post subject:  Re: Desired range of action adjustment at the nut?
So many things to discuss with a drawing like that. Your courageous just to put it out there!

Just one generalization I'd like to mention from a repair persons perspective.
I'm a pretty calm even tempered sort, but nothing, I mean NOTHING!, causes me to question the meaning of life like struggling to locate a buzz. My first, gut reaction to seeing so many small pieces contacting one another is dread. In the space between theoretical drawings and the real world, Murphy relaxes in his palace. Your going to need a plan to take him out. I fear at the moment that bastard is doing this laughing6-hehe
Author:  Chris Pile [ Mon Dec 12, 2016 8:19 pm ]
Post subject:  Re: Desired range of action adjustment at the nut?
OK, Leo - you've posted engineering drawings.... How much do you estimate to produce say... 100 pieces? Do you plan on marketing this nut? How about parts for when the buyer promptly loses half the bits? (IT WILL HAPPEN)
Author:  Hesh [ Mon Dec 12, 2016 9:22 pm ]
Post subject:  Re: Desired range of action adjustment at the nut?
There is no substitute for learning to cut nut slots properly.

We all go though this, we all cut slots too low at times. Well cut, individually adjusted nut slots are a joy and not difficult to learn to do.

KISS seems to fit here in terms of what I tell myself.
Author:  Durero [ Mon Dec 12, 2016 10:46 pm ]
Post subject:  Re: Desired range of action adjustment at the nut?
david farmer wrote:
So many things to discuss with a drawing like that. Your courageous just to put it out there!

Just one generalization I'd like to mention from a repair persons perspective.
I'm a pretty calm even tempered sort, but nothing, I mean NOTHING!, causes me to question the meaning of life like struggling to locate a buzz. My first, gut reaction to seeing so many small pieces contacting one another is dread. In the space between theoretical drawings and the real world, Murphy relaxes in his palace. Your going to need a plan to take him out. I fear at the moment that bastard is doing this laughing6-hehe


I appreciate your thoughts David. It is perhaps foolish of me to post such drawings but to me the modelling exercises are just that, exercises. Their purpose is to explore and see if I can reproduce the action and intonation adjustability which has been taken for granted at the bridge end of electric guitars for many decades now.

I'm equally concerned about buzz, and if I can't make something that is buzz-free I'll be definitely sticking with my nut files.
Author:  Durero [ Mon Dec 12, 2016 10:57 pm ]
Post subject:  Re: Desired range of action adjustment at the nut?
Chris Pile wrote:
OK, Leo - you've posted engineering drawings.... How much do you estimate to produce say... 100 pieces? Do you plan on marketing this nut? How about parts for when the buyer promptly loses half the bits? (IT WILL HAPPEN)


Chris I can assure you that I am the only person I intend to inflict this stuff on! If I can achieve a working design then I will put them on my own instruments. I genuinely don't expect anyone else to be interested beyond mere curiosity.

But your and David's concerns about repairability and small parts getting lost are good points. Electric guitar & bass bridge saddle systems typically have numerous finicky little parts, but the more elements which can be captive by design instead of loose, the better.

As for production I have my own small CNC mill so a production total of 1 is what I intend to start with.
Author:  Durero [ Mon Dec 12, 2016 11:17 pm ]
Post subject:  Re: Desired range of action adjustment at the nut?
Hesh wrote:
There is no substitute for learning to cut nut slots properly.

We all go though this, we all cut slots too low at times. Well cut, individually adjusted nut slots are a joy and not difficult to learn to do.

KISS seems to fit here in terms of what I tell myself.



I absolutely agree that there is no substitute for nut making skills. One setup or repair is all it takes to prove that truth.

There is certainly a good chance that I will not end up with a practical, machinable design that performs as well as a traditional nut.

But the question of why can't we have fully adjustable nuts like we have fully adjustable electric bridges bothers me enough to keep pursuing an answer, at least for now.


Do you have any thought on the original question Hesh? How much height adjustment range would be desirable at the nut?

If so I'd love to hear. :)
Author:  Hesh [ Tue Dec 13, 2016 5:51 am ]
Post subject:  Re: Desired range of action adjustment at the nut?
Durero wrote:
Hesh wrote:
There is no substitute for learning to cut nut slots properly.

We all go though this, we all cut slots too low at times. Well cut, individually adjusted nut slots are a joy and not difficult to learn to do.

KISS seems to fit here in terms of what I tell myself.



I absolutely agree that there is no substitute for nut making skills. One setup or repair is all it takes to prove that truth.

There is certainly a good chance that I will not end up with a practical, machinable design that performs as well as a traditional nut.

But the question of why can't we have fully adjustable nuts like we have fully adjustable electric bridges bothers me enough to keep pursuing an answer, at least for now.


Do you have any thought on the original question Hesh? How much height adjustment range would be desirable at the nut?

If so I'd love to hear. :)


Sure nothing like actually having the question that we ask answered..... :? :o [headinwall] :D

It depends.... and I am not trying to be a smart ass here. It depends on the type of guitar and subsequently the string gauges used. For a Chapman Stick with some of the thicker strings 1/8" might be necessary. For the treble strings half of that would be fine IME.

Let's back up first and actually quantify how low nut slots should be set up. If you spent some time in our shop you would learn that well cut nut slots are so very low at times that you may have never experienced them before. I'm not kidding. I went nearly 50 years before I learned just how low nut slots should be cut.

You mentioned having the adjustability at the nut end that we have at the saddle end. Are you aware that this entire notion of nut compensation with methods such as Buzz Feitin to many of us are NOT necessary for 95% of players if the nut slots are manually well cut to begin with? High nut slots pull strings sharp and benefit from nut compensation. Cut the nut slots low and like a pro will and this all goes away and nut compensation is not necessary.

There will be some disagreement here but I don't care, nut compensation for 95% of the playing community would be of NO benefit what so ever if their nut slots are cut as low as we do and many pros cut them in the first place.

Anyway we set nut slots at sub one ten thousandths of an inch settings at times because that's what works best. The gap that we are working with for some of the treble strings is less than one ten thousandths.... Keep that in mind because what ever adjustment measurement implementation that you come up with should not only have adjustment range in mind but even more important the precision of the level of adjustment..... Can you get me reliably and repeatedly one half a thou of an inch of adjustment because that's what I would need to do what I do over and over again every day cutting nut slots.

Also keep in mind that we repair guys are often very opinionated and since we see all manner of BS snake oil crap... that was never ready for prime time what ever you come up with has to stand the Hesh test...:) The Hesh test is does this thing actually work well enough or is this Hesh guy going to go off on it because of his irritable bowel syndrome and rip the entire thing off, throw it away and replace it with a well made, bone conventional nut...:) And I am one of the nicer repair guys too...;)

You will have other issues such as who wants their string bearing on metal???? There was a time when the electric guitar crowd liked brass but those days are passed although Carlos has his PRS nuts specially impregnated in the slots with brass but he's Carlos and supernatural...... the rest of us are mere mortals.

I appreciate the interest in innovation and we ALL at times think this way. But with no insult intended don't you think that some very bright men and woman have been to this movie before? More specifically not only is conventional guitar design pretty eloquent and efficient it just could be that anything that you or anyone might come up with has been done before or is, ultimately...... a solution looking for a problem. Learn to cut nut slots well and you will see what I mean about a solution looking for a problem.

PS: Not only did I struggle with cutting too low at times I struggled with the angle of the cut and file technique. If you ever want to call me, number is on-line by googling Ann Arbor Guitars, I would be very happy to give you some pointers on how I cut nut slots, conventionally. I do admire those like you who think of a better mouse trap. Just keep in mind that countless others have been here too. Sometimes the best way to actually be innovative is to do what it takes to learn the existing methods well and then if you still feel like it - tear them a new one!
Author:  Chris Pile [ Tue Dec 13, 2016 9:34 am ]
Post subject:  Re: Desired range of action adjustment at the nut?
Preach it, brother Hesh!

I am reminded of the drummer who excitedly brought me a string winder he had made in shop class (looked like a StewMac ZapIt), thinking he was going to make a mint. I said NICE, and pulled a handful of mine out of a tool tray. You should have seen his face fall.
Author:  kencierp [ Tue Dec 13, 2016 9:46 am ]
Post subject:  Re: Desired range of action adjustment at the nut?
As Hesh indicated others have done more than thought about such a device.

Compensation and action:

https://www.google.com/patents/US20100005944
Author:  jfmckenna [ Tue Dec 13, 2016 10:04 am ]
Post subject:  Re: Desired range of action adjustment at the nut?
Well, I don't want to discourage you because I think what you are doing is very cool. I don't even see the need for compensating a nut because the far majority of people are happy with the impossibility of tuning a guitar to perfection anyway and only so many people are truly bothered by it. But what ever it is you are doing is pretty cool :)
Author:  kencierp [ Tue Dec 13, 2016 10:59 am ]
Post subject:  Re: Desired range of action adjustment at the nut?
While my visual sense of design will pretty much accept anything on an electric guitar -- metal components on an acoustic will prevent me from even taking such an instrument off the rack to try out. $02
Author:  Durero [ Wed Dec 14, 2016 9:16 pm ]
Post subject:  Re: Desired range of action adjustment at the nut?
kencierp wrote:
As Hesh indicated others have done more than thought about such a device.

Compensation and action:

https://www.google.com/patents/US20100005944


Thanks for posting that Ken. I've done repeated patent searches for a number of years now and I've seen that patent a bunch of times, but never realized that there's an action adjustment on it! It just looks like and intonation adjustment with a locking function, but it's not.

I wonder if there are any for sale anywhere?
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