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I've got a client who has requested I build something capable of VERY low action. 1.5mm on the treble and not much higher on the bass.

What would any of you recommend for what I could do to plan accordingly with regard to neck angle if I want to keep my own standard bridge and saddle height?

Thanks,

Dave

You will most likely need a very straight neck with regards to string relief, and super level frets.
So, set your neck angle and bridge position accordingly, and even if you've done a perfect job seating you frets, plan on skimming the tops a hair and polishing the frets out. The actual neck angle will depend on the thickness of your bridge and your desired saddle height above the bridge. I like to arch my UFB to meet the end of the fretboard, keeping the fret plane as straight as I can, as I don't like that bit of falloff where the neck meets the body.
1.5 millimeters is equivelant to 4/64ths in inches, and for fingerstyle artists with very low action, I set my treble strings right at 3/64th, and the bass strings at 4/64th plus about 128th or less.
To achive this, I set the neck perfectly straight, adjust the heights to 1/32 inch on the treble side, set the bass side accordingly, and the adjust a TEENY bit of relief in the neck to bring the treble side up a hair.
I measure my strings individually, I set the bass strings all the same height, the B string a touch below those, and the high E a touch below the B.
Sounds like your guy wants his basically all the same height above the fretboard. I find that the treble strings have a tighter vibration and can be set a hair lower than the basses.

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Old growth, shmold growth!

Dave, you shouldn't have much trouble with 1.5 on the trebles, but will need to go up to at least 2mm on the bass side I think. My standard action is 1.5mm/2.3mm at the 12th fret.
When I build my instruments I wait until the body is complete and set a shim at the bridge location to allow me to measure the required neck angle for a given bridge height. The shim is generally in .1 range for a .25 finger board and .375 bridge.

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Jim Watts
http://jameswattsguitars.com

you need a certain amount of action to account for the string movement . You can't do lower that that . At best a +2mm as Jim Watts suggested . If you get into this professionally , you can't allow the customer to request something that isn't possible. No one wins in that situation.
If he wants a soft action he needs a good nut set up and a good neck . This can be doable but it isn't as easy as it seems.

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John Hall
blues creek guitars
Authorized CF Martin Repair
Co President of ASIA
You Don't know what you don't know until you know it

A compound radius will help out, but it's mostly the player's style that determines final adjustments of the action.

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"Act your age, not your shoe size" - Prince

Jim Watts' response is on par with how I set the neck angle.
My question goes to, should that shim be any bigger to plan ahead and make it easier to get the action down where he wants it after the top settles in?

You probably don't have to do anything different than what you're doing. I routinely set the action that low on guitars that have standard neck sets (if you can call Martin's neck set "standard" at all) with no ill effects. Sometimes the saddle looks a little low if the tech got the neck angle a little shallow, but other than that, no problem.
Just be careful not to underset the neck angle and you'll be fine. If the neck settles in, it will likely settle in higher. If you make the shim thicker, your bridge will be thicker, and your saddle shorter. Better to make the bridge (and shim) thinner and the saddle taller, to account for future action adjustments as the guitar settles in, that way you will always have enough saddle height to drive the lowest frequencies in the top. I like to see 1/8th inch saddle height above the bridge with the neck straight and the strings at the 1/32 inch mark above the frets, as determined with a straightedge resting at the first fret and on top of the saddle. Most of my guitars go to fingerstyle guitarists with super low action and phenomenal technique.
Chris is right on target that the players technique will determine the final setup. Not everyone can play with action that low, but some can. If you can make them happy when they request it instead of telling them that what they want is impossible, you will have a wider customer base in the long run. Of course, if word gets out that you can do that, all the pickiest sons'a'bi^%#es in town will start frequenting your shop, requesting the lowest action on earth. You might not want that if you want to do quicker easier setups. I know one guy who has a sign that says "If you want your action lower, set it yourself!"

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Old growth, shmold growth!

Dave, here's the way I look at it. Let's say your "normal" action is .020" higher. That means your saddle on this one would need to be .040" lower. If you want to keep the .040" on the saddle, instead of having a shorter saddle, or thinner bridge you need to add .040" to your "normal" shim. The geometry of the box would need to be a little different to keep the FB level past the 14th fret. Another option would be a thicker fingerboard, if it doesn't make the neck too thick. I hope I explained this OK, I understand it, but have trouble putting stuff in words sometimes.

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I didn't mean to say it, but I meant what I said.
http://www.brackettinstruments.com/

Why would a compound fingerboard help? I get it for extreme bends on an elctric guitar where you can "fret out" against the radius of the fret, but I don't really see it on an acoustic guitar. I've done compound fingerboards before but it just dosn't seem to matter IMO.

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Jim Watts
http://jameswattsguitars.com

Obviously as mentioned, you'll need a slight increase in the neck angle to maintain proper saddle height with super low action but don't overset it. It would be better to error on not having enough angle and fix it after the guitar has settled in. With a bolt-on neck it's pretty easy to increase the angle with flossing but a real bear to lessen it.

You can support the headstock and add 6lbs of weight to each shoulder of the upper bout to get some idea where the neck will go with tension but you still won't know exactly how much the instrument will settle in strung up so I'd probably stick pretty close to what you usually do for neck angle and tweak it after string up. This is where a double tenon neck really shines.

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It's not what you don't know that hurts you, it's what you do know that's wrong.

One of my students strung up his guitar for the first time last night .. the initial saddle height left the action on the low E at around 75-80 thou at the 12th fret, with almost no relief, like 2-3 thou .... you could play every note on that string and nothing fretted out, as in each note at each fret was clear and distinct, but with even moderate pick attack there was a rattle on every fret, meaning that the action at that setting just cant support average playing .. it needs to be more like 90-95 thou. If you customer has the lightest of touch, it might work.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

A fingerstyle artist with good control could play that low. Here's a video of Shaun Hopper playing his Larivee that I've refretted with stainless steel frets, bone nut and saddle.

http://www.youtube.com/watch?v=7BhCdhiZpD8

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Old growth, shmold growth!

Very nice .. but he is not what I would call an "average" player ..... and its more his style that makes it work .. I had a baritone on display a few years back that Don Ross sat and tried out ... it was set where it worked well for me, but Don attacks everything so hard that the low strings buzzed too much for him, he would have preferred slightly higher action. Like was mentioned its all player dependant. Low action doesnt work for everyone ...

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

The player I am building for is used to making this action work for the rest of his guitars.

Light, light, light touch. No pick. Fingerstyle only.


So I'm seeing hope and appreciate the suggestions.

What I'm not so hopeful about is having that action set before the guitar gets shipped and the top settles six months later.


Dave

Setups dont last forever .. especially on new guitars .. things will move as the tension takes affect ... I find most of my necks need a truss rod adjustment in 4-6 months, as the neck wood relaxes, and pulls up .. more truss rd to bring it back.

After its done, keep it around the shop for 3-4 weeks and see what it does ....

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

I agree. Not everyone can get away with it. I'm responding to the posts that specify that you can't really have a bass string that low. You can, if the player is up to it. Each situation is unique and requires evaluation.




I wouldn't worry about that so much, just set everything where he likes it. Tops settle in, but he should expect to have the instrument set up several months after it's completed. If you build in a 45% relative humidity environment, you should be okay. The problem occurs if the guitar leaves the shop with a shallow neck angle and a low saddle, and the action settles high, with no room to adjust the saddle down. If you plan carefully, that won't happen.

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Old growth, shmold growth!

If you give the bass side more relief you can lower the action. .005 high E .010 low E

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Ken Franklin
clumsy yet persistent
https://www.kenfranklinukulele.com

Reminds me of a luthier's site....can't recall who... advocating shaping relief into the fretboard. The treble side was sanded a bit convex & the bass a bit concave, so under tension, treble relief would go to zero and bass enough to prevent buzz.

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Dave
Milton, ON

Some players might want the action set lower than they ultimately want just so they can avoid a set up fee down the road.

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Ken Franklin
clumsy yet persistent
https://www.kenfranklinukulele.com