getting the right nut height

[Songdog]

I think the nut is a bit too high on my bass. It has an adjustable nut, but it's already down all the way. I started looking into this because fingering on the first few frets feels harder than it ought to be.

First question: what's the right height? My E string is about .030" over the first fret, the G string about .028" (measured with feeler gauges). Fretting at the first fret and measuring at the second fret, I get about .010" - .011". I think this agrees with what my fingers are saying: the nut could be lower.

Second question: the nut slots look a little bit rough. Especially on the A string, I can see very clearly that this bass spent a lot of its life with roundwound strings; the other slots don't have quite the same impressions from the windings, but aren't real smooth. Does this matter much? It seems to me like it could cause some slight problems tuning (although I haven't really noticed any problems). So, if I want to lower the nut height, should the first step be to file the nut slots to polish them? I think I'd need to take it to a pro, since I'm not confident in my ability to maintain the right radius.

Third question: it sure seems like the height needs to come down more than it would just from a little cleanup of the slots, so is the right way to take some material off the bottom of the adjustable nut? What's the right tool and technique for this job? A fine file? Sandpaper on a flat surface?

The simultaneous joy and frustration of an Alembic bass is that it's so good that any minor deviation from perfection is very obvious 

[JimmyJ]

You might get some differing opinions on this subject but my personal preference is to treat the nut like a "zero fret".  For me I want the clearance between the string and the first fret to be about the same as when holding the string down on the 1st fret and observing the clearance above the 2nd fret.  Because a "taller" nut makes for a higher action over the entire fingerboard.  I think some folks prefer to have the nut just a hair taller than that.

I also have a somewhat unconventional method for deepening our bridge saddle and nut slots.  I play ghs Boomers which are nickel-plated steel windings.  Not as hard a material as steel roundwounds but certainly harder than brass.   I mount a portion of the string on a wooden block and use that as a nut file.  It takes some elbow grease but eventually you can deepen the slot - and the resulting size will be a perfect match to the strings you use.

I'd also recommend making a small gauge out of cardboard with the arc of a 12" circle.  This is the radius of our fingerboards and you will want to check the bottoms of the slots (or even the tops of the strings) to be sure you are staying close to that curve.  That way one string doesn't end up higher than another.

I am a dabbler so if you are not up for that kind of messing around I would certainly understand. 

And yes, if the overall string height seems too high and you've run out of adjustability, you could also just remover material from the bottom.  A flat file would be the logical tool. 

Stand by for better information from actual qualified folks in here. 

Jimmy J

[edwardofhuncote]

Jimmy's advice as always, is dialed-in. I've got a shop, and access to nut slotting files, so I'd only be bypassing his strings affixed to wood blocks. That's a great hack though, and to tell the truth, I work with of a lot of wood nuts (on upright bass) that some homemade files would be better suited than the chainsaw and gunsmith files I have modified for use.

You had the right idea, but just had things a little bit backwards in determining how much clearance there is. (if I've read and understood your post correctly)

Instead of fretting at the first fret and measuring clearances at the second one, I put a large guitar capo on between the second and third frets, and measure the clearance from top of fret to bottom of string at the first fret. That's how you get the 'zero fret' effect Jimmy J's talking about. Getting there is another thing... if your nut is evenly high, then yeah, just flat file the bottom of it a few thousandths so all four strings come down the same amount. If you go too far, use the adjustment screws and raise it up. Make sure you keep it vertical when filing. It's easy to drift, so check your fit often.

Just bring it by tomorrow... I'll fix you up. It ain't but 3500 mi. Leave now and beat the morning drivetime rush. 😄

[Songdog]

@edwardofhuncote, thanks for the offer to help out - but I'm kinda snowed in here (foothills of the Cascades) so I'll regretfully have to decline. 

What's the rationale for putting the capo between the 2nd and 3rd frets and measuring at the 1st, rather than simply measuring at the 1st under the open string? Is this to prevent unwanted buzzing of the string behind where it is fretted?

@JimmyJ, the idea of making a 12" radius gauge is priceless - I might try to find something a little more durable than cardboard. This will be very helpful to determine whether the slots are still even with this radius. And I think I have some old, dead Rotosounds around here somewhere, they'd probably make excellent nut files.

Does anyone have any thoughts about whether I should even be concerned about the roughness in the nut slots? I've also noticed the impression of roundwound strings on a couple of bridge saddles. Maybe I'm getting a little too deep in finicky details?

[edwardofhuncote]

What's the rationale for putting the capo between the 2nd and 3rd frets and measuring at the 1st, rather than simply measuring at the 1st under the open string? Is this to prevent unwanted buzzing of the string behind where it is fretted?

Just geometry. When measuring (with your feeler gauges) the amount of space that's measured between the top of the first fret and the bottom of the string is the amount that can be removed from the nut slot before the string will bottom out on the fret. (and buzz) When you are slotting the nut one string at a time, add a couple thousandths to that total, and stop when the string just barely clears that fret. If it clears the first, you're gold, providing your fretwork is all true and the neck geometry/relief is correct. And really, you might check that first. T'is the season for truss rod adjustment. 😉


On those slots, unless the strings are binding up in them, I wouldn't sweat it much. If you're going to file them, that'll take care of it anyway. 

[gtrguy]

I am going to be the devils advocate here and say that I never use gauges, etc. I go by what feels right, especially since no two instruments are the same and everyone likes things the way they want and not necessarily the way someone suggests that they be.

I use a desk mount sander to evenly remove metal from a nut, being careful not to get burned and to do it in an even fashion. I use small round files to carefully dress bass nut slots if really needed first. I select generic small round files for bass but for guitar, the professional nut files (Stew Mac etc) are the way to go. Go to far and you may end up with an uneven depth across the string slots. Frankly, as often as not, nut slots even if not super smooth seem to still work fine. You may need a truss rod adjustment as well. Dressing the frets might be a good idea too. All these things are related and can interact with each other.

Sometimes a bad string can make your bass behave in odd ways. like not intonate correctly or sound out of tune on one particular fret. Various size and brands of strings can also make a difference and sometimes changing them can cure oddball problems.

Just my 2 cents worth.

[JimmyJ]

Nothing devilish about what you said there David, the goal is for it all to feel good so however you can get there.  I don't use feeler gauges either, I just don't think it's that super-critical a thing. 

Here's a pic of one of my homemade radius checkers - just a paper version I made as an example.  Interestingly, because the string sizes increase incrementally, checking the tops seems to closely reflect the radius of the bottoms.   

Jimmy J

[mica]

Def removing material from the bottom of the nut will maintain radius and if the slots aren't causing any issue the way they are I'd probably leave them if it were my own bass. The nice thing about removing from the bottom is that even if you take a little too much away you can always raise it up. And sandpaper on a flat surface is great - you can attach it with carpet tape to keep it from shifting around. Taking material off the bottom is something you can do yourself.

[Songdog]

The nice thing about removing from the bottom is that even if you take a little too much away you can always raise it up. And sandpaper on a flat surface is great - you can attach it with carpet tape to keep it from shifting around. Taking material off the bottom is something you can do yourself.

Thanks, Mica. I do my own setup adjustments (truss rods, action, intonation) with confidence, but I've never done anything except a very little careful widening of a slot on one of my other basses because I didn't want to find out the hard way how low is too low. Taking a little off the bottom is something I'm much more comfortable with. I think I'll follow your recommendation and leave the slots alone for now, as I haven't noticed any problems with the strings binding when I tune.

Anyone have a suggestion on what grit sandpaper to use, before I head to the hardware store?

Regarding measuring - I like measurements 1) as an approximate starting point for tweaking relief or action; and 2) as a sanity check if something feels "off". Then I adjust by sound and feel until my bass reaches what I think of as perfection.

And yeah, my truss rod adjustment needs some tweaking, since the weather here has been unusually cold and dry. I felt it first, and my feeler gauges confirmed it.

[keith_h]

David, I use gauges for speed and to get repeatable results. When I first setup an instrument I get it playing the way I like then take measurements for future adjustments. This is more psychological but I've also found it helps me when I'm having one of those days where nothing seems to feel or sound right. I set the instrument knowing it is what I've been using for years so it has to be right and that all will be better tomorrow. 

[gtrguy]

Wet 320 sandpaper on a piece of glass will slowly work. You could probably do 220 also. Use it wet.