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Feb 29, 2024 - 9:04:29 AM
3032 posts since 2/12/2005

I got another banjo and the 1st & 2nd strings are too low, affecting playability at the first few frets. 

I did some measuring and find that the nut is unlevel. See photo.  The slant is very slight, but you definitely feel the difference when you play (compared to three other banjos I have).

1st string has less than 1/64" clearance to the first fret. 3rd is more normal ~1/32" clearance to the first fret.

Unlevel nut photo

But, when I measure the nut, it is 1/4" tall on both sides.  So, my conclusion is that the neck is slightly UN-parallel from the fingerboard to the neck area under the nut.  In other words, the slot that was cut for the nut is unlevel.

I have thought of several fixes but maybe you could chime in on the "best" way.

Fix 1: Buy a new taller nut and sand it to have a slightly sloped base to compensate for the defective nut slot.

Fix 2: Sand or use my mini router plane (manual) to level out the nut slot.  Then, strings would be uniformly low so --

     2a) Get a taller nut and fit it to have whatever string clearances I like

     2b) Put a shim under the existing nut.  About 1/32" thick (say 0.030"-0.035").

Fix 3: Use some wood filler in the bottom of the nut slot (e.g., bondo brand), Then, level it out to the proper level. The resulting new material (after sanding or whatever) would be a "wedge" about 1/32 tapering to a feather edge of 0" at the 4th string side.  Alt: An epoxy might be "harder" re: better sound transmission.

I'm pretty sure I could make any of these ideas work, but maybe there's some reason for preferring one idea over the others.

Additional ideas invited too...  Thank you in advance!

Note: Although I am not a luthier, I have strong woodworking skills and the usual tools for cutting dovetails, hand mortising, etc.

Edited by - randybartlett on 02/29/2024 09:05:32

Feb 29, 2024 - 9:44:45 AM

15032 posts since 6/2/2008
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I'm not a luthier, either, just a tinkerer for some repairs, so I'll try not to venture too far out onto a limb. I'm sure more knowledgeable folks will chime in.

But first, I don't know about 1/64" first fret clearance being too low or 1/32" being more normal. I believe the 4th string needs more clearance because of its greater thickness (typically double the 1st string or more) and the greater vibrational space it needs. Also, 1/64 (0.0156) sounds right. Steve Davis has commented here that 0.01 to 0.015 is a good range.

As to what to do with the nut, I agree with you that something is skewed or off. I think you should investigate every possibility to determine whether it's the entire fretboard (in which case, I have no idea how you accommodate/compensate or fix) or the base of the nut slot (which is fixable).

If you're sure the fretboard is fine and the base of the nut slot is not parallel to the surface of the board, then I guess you either have to lower the high side of slot or raise the low side. Your inspection should tell you which to do. If raising the low side seems to be the fix, I'd shim with real wood (your fix "2b"), not build up any sort of compound. I sanded the base of a nut too low maybe 12 years ago and shimmed it with a strip of .01 wood purfling as a temporary fix until I got around to replacing the nut -- which I have yet to do.

Since you can feel the difference, something needs to be done.

Good luck.

Edited by - Old Hickory on 02/29/2024 09:46:43

Feb 29, 2024 - 9:53:14 AM
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Alex Z

USA

5769 posts since 12/7/2006

"the slot that was cut for the nut is unlevel"

Considering your measurements, likely.

Since for most of the possible solutions, the nut has to be removed anyway, go ahead and remove it.  See what's under there.

Level the slot, and replace the nut.

The nut seems to fit the strings well and it looks nice.  No reason not to keep using it.

 

Glue for nut should be a tiny drop of white glue or hide glue, just to hold it in place.

But no telling how the existing nut was glued.  So the most potentially troublesome part of the operation is to  extract the nut without damage to the nut or the banjo.  There are ways, and I've done it, but I'm no expert.  Will leave that advice to the experts that have had experience with many types of nuts and glues. 

Edited by - Alex Z on 02/29/2024 09:54:24

Feb 29, 2024 - 9:59 AM

5404 posts since 11/20/2004

The top of the nut is not level, but the nut slot may be. The top could have been filed down. To find out, you will likely need to remove it. You could then make a new one and fit and file it correctly.
Or, the easy fix is take the strings out of the slots, sprinkle baking soda in the slot, add a drop of superglue, give it a few minutes, and refile. Some say just use superglue, but I have always used baking soda. Bone dust would be good if you have any, as well. Remember to mask the front and back of the nut to protect from glue drips.

Feb 29, 2024 - 10:06:38 AM

15032 posts since 6/2/2008
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quote:
Originally posted by lightgauge

The top of the nut is not level, but the nut slot may be. The top could have been filed down. 


He said he measures the nut as 1/4-inch tall at both ends. So the problem is the nut slot or the fretboard.

There's another fix that accommodates to the nut slot or fretboard as they are, and that's to deepen the string slots for the 3rd and 4th strings to get more comfortable first fret clearance, then filing down the top of the nut to make it visually more even. This is a cosmetic fix that doesn't get to why an evenly cut nut sits unevenly on the neck.

Feb 29, 2024 - 11:27:16 AM
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Alex Z

USA

5769 posts since 12/7/2006

One more note for the poster:  If you're measuring string height above the nut in 64ths or 32nds, that's much too coarse for this type of work.  Get those feeler gauges out for the final adjustments!  smiley

We're talking string heights above the first fret that will be in the .015 - .022" range, depending on the string.  So if the string heights are set by measurement, degree of accuracy should be around +- .002" 

Mar 3, 2024 - 4:05:23 PM

79568 posts since 5/9/2007

Feeler gauge or banjo string will measure the string to 1st fret clearance.
.015" to .026" is a lot and will intonate rather poorly in the 1st 7 frets.
Minimum string to top of 1st fret is .010" and I wouldn't go more than .013".
Anything less than '010" is prone to buzz.I keep my 1st fret clearance at .011".Nice low action and big,clear notes.
Low slots can be filled and recut with super glue or by cutting a .010" brass feeler gauge blade as a shim under the nut.
Slots would then need recutting to achieve .010" to .013" 1st fret clearance.

Mar 3, 2024 - 6:57:16 PM

rcc56

USA

5053 posts since 2/20/2016

Before you do anything else, go to http://www.frets.com, go to the "big index page," select "items for luthiers," and read everything that has to do with nuts.

A good way to check the height of nut slots is to fret the string between the 2nd and 3rd frets.  The string should then just clear the 1st fret by .005" to .010".  For the 4th string on a banjo or the 6th string on a guitar, it's best to leave the slot a shade higher than on the treble strings.  After you've cut a few dozen, you get a feel for what's the lowest you can get away with. 

If you're a woodworker, you should have most of the tools you need for cutting a new nut.  If you don't have gauged files to cut the slots, you can use a razor saw and the narrowest needle files you can find.  It is necessary to cut the slots with some back-angle [perhaps 10 - 20 degrees] towards the peghead to avoid a "sitar" effect.  All of the above is covered in great detail with plenty of pictures on the frets.com website.

Buy two or three pieces of bone in case you mess up the first one.  The most common mistake is to cut the slots too low.  When you get close to the correct slot height, use only one or two strokes at a time to finish it off.

If you want a nice shiny finish, dry sand the nut to 600 or 800, then apply a little fine polishing compound or swirl remover.  When it's finished, use only one or two drops of glue to secure the nut in place.

Edited by - rcc56 on 03/03/2024 19:09:54

Mar 4, 2024 - 7:54:23 AM

79568 posts since 5/9/2007

I was taught my .010" minimum 1st fret clearance by John Blodgett who worked at Woodsound Studios for many years.He repaired a broken neck to invisible for me once and I spent some time visiting that shop.
Less than .010" over 1 is inviting limitations and weak buzz notes concerning down-stream frets being too close.
Solid body electric guitars can be between .006 - .008 because of the structural stability of a plank.
A banjo's stability in the vertical is dependent on a stretched membrane under the bridge.

Mar 4, 2024 - 10:16:37 AM
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617 posts since 11/2/2009

I know completely nothing about this (except what I learned from Steve D about string height at the first fret in another thread), but I would throw out, for thoughts, that before modding the nut, I would shim it so it is level, and then mod the nut (IF necessary). That assumes the nut can be removed without damage to binding, fretboard or headstock. Value of the banjo may play a role in the nut-removal decision, as well. I had a nut on '27 that was level but had been cut a little deep on first and second strings - removing the nut could have been a disaster, but my luthier filled them to bring them Steve D's spec at the first fret, and everything has been fine since. I do have a note to this, and that I think you should make sure that you have the action at the 12th fret where you want it before you mod the nut, else, if you drop the action at the 12th after modding the nut, you will be changing, a bit, the string height at the first fret, and may wind up with a buzz.

But see my first sentence, above.

Edited by - gcpicken on 03/04/2024 10:26:04

Mar 4, 2024 - 2:19:11 PM

79568 posts since 5/9/2007

And a 7th fret neck relief of .015" .
My .011" at 1 and .015" relief at 7 lets me have .092" at 12 and .098" at 22.
Wicked low and powerful.

Mar 4, 2024 - 4:02:55 PM

19 posts since 4/23/2011

Also a solution, place a ZeroGlide for Banjo.

Mar 5, 2024 - 8:37:27 AM

2397 posts since 2/9/2007

First off, do any of the open strings buzz or rattle against the frets? If one does, does it also buzz when fretted at the first fret? how about the 2nd and 3rd?
If a string buzzes when open, but sounds clearly when fretted, its nut slot is too low. If it buzzes when fretted, too, you'll need to check the bridge height, head tension, neck set, fingerboard relief, and fret level, before messing with the nut.
To judge the 1st fret clearance, depress the string between the 2nd and 3rd fret. There shouldn't be much more than a couple thousandths between the string and the 1st fret. If you can slip even a thin piece of paper in there easily, it's higher than it should be.
You say that the LOW action affects "playability". If you mean that the sound is OK, but you want to feel the string more, you should try heavier strings. DO NOT raise the action at the nut. It will ruin your intonation. Every thousandth of excess height at the nut sharpens the notes at the first couple of frets a bit more.

Mar 5, 2024 - 9:37:56 AM

3032 posts since 2/12/2005

I was traveling but plan to focus on this today. Last week, I put a 0.010" shim under half of the nut and it took away most of the unlevel appearance, removed the feeling of poor playability i had sensed, and (oddly enough) improved tone. I could just be happy now but now I am curious, so I will investigate further.

I plan on measuring all 4 banjos I have. I'll put my findings here if interesting.

One further question... measured from the fingerboard, how much variation is expected in height of fret 1 and fret 2? I noticed my fret is 1 is higher than fret 2. I will measure that.

Mar 5, 2024 - 9:54:39 AM

2397 posts since 2/9/2007

quote:
Originally posted by randybartlett


One further question... measured from the fingerboard, how much variation is expected in height of fret 1 and fret 2? I noticed my fret is 1 is higher than fret 2. I will measure that.


All depends on how level the fingerboard is.  You want the TOPS of the frets to be level.  If you're using a short straight edge to check by "rocking", it's easy to overlook that first fret being too high.  Try fretting each string at both the 1st and 4th frets. If you can see any light between the 2nd fret and the string, the 1st fret's too high (or the 2nd is too low).

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