Nut File Selection

Questions and answers for beginners. If you have a question, so do most other people.
scamp
Posts: 223
Joined: Sat Mar 26, 2022 8:19 pm

Nut File Selection

Post by scamp »

I could use some advice.

I need to order some nut files for my OM kit as I am getting to the final stages of my build.
The Martin strings I typically use have the following width dimensions...

E 0.013 inch
B 0.17 inch
G 0.26 inch
D 0.35 inch
A 0.45 inch
E 0.056 inch

I looked at some files from Philadelphia Luthiers and others and there isn't a direct match to these dimensions( I guess which is to be expected ). So... Is there a recommended set of file widths for an Martin OM type guitar? Is it better to have the file width slightly smaller or larger than the string? Also... if there is any recommendations on a good set at a reasonable price.

Thanks
tippie53
Posts: 7011
Joined: Fri Mar 03, 2006 7:09 pm
Location: Hegins, Pa
Contact:

Re: Nut File Selection

Post by tippie53 »

John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
Skarsaune
Posts: 239
Joined: Mon Dec 03, 2018 9:12 am

Re: Nut File Selection

Post by Skarsaune »

That set John linked is an electric set, smaller than your strings. That site does have an acoustic set, also smaller than the strings you prefer.

The nut slot needs to be just enough larger than the string so the string can freely move (such as during tuning). A slot can be made bigger than the file you are using by manipulating the file, rocking it side to side.

Stew Mac has a bunch of individually sized ones but they are $$$. Best to find a set that’s close and may be add a couple of sizes.
scamp
Posts: 223
Joined: Sat Mar 26, 2022 8:19 pm

Re: Nut File Selection

Post by scamp »

Thanks. The set is supposedly for electric guitars but I'm assuming it has the correct file widths for acoustic. Correct?

Also.. the width of the files are...

1x 25-0010 Nut File (0.010 Inch, W12 x 0.25)
1x 25-0013 Nut File (0.013 Inch, W12 x 0.33)
1x 25-0017 Nut File (0.017 Inch, W12 x 0.43)
1x 25-0026 Nut File (0.026 Inch, W12 x 0.66)
1x 25-0036 Nut File (0.036 Inch, W12 x 0.91)
1x 25-0046 Nut File (0.046 Inch, W12 x 1.17)

So.. do you use the 0.010 inch file for the high E string which is 0.013 inches
And the 0.013 inch file for B string which is 0.17 inches
And the 0.17 inch file for the G string with is 0.26 inches
And the 0.26 inch file for the D string with is 0.35 inches
And the 0.36 inch file for the A string which is 0.45 inches
And the 0.46 inch file for the low E sting with is 0.56 inches

Basically you are using a smaller file width than the string?
Diane Kauffmds
Posts: 3246
Joined: Sun Mar 09, 2014 8:13 pm

Re: Nut File Selection

Post by Diane Kauffmds »

I use Mitchell abrasive cord on my slots. It smooths and enlarges the slots just enough to ensure a smooth tuning. You can find it on amazon. Use the smallest file on treble E (string 1) and go up from there.
Diane Kauffmann
Country Roads Guitars
countryroadsguitars@gmail.com
tippie53
Posts: 7011
Joined: Fri Mar 03, 2006 7:09 pm
Location: Hegins, Pa
Contact:

Re: Nut File Selection

Post by tippie53 »

https://www.amazon.com/Grizzly-T25458-N ... B00DQJOVRU
this is a good set
remember you don't need to be to the thousandths just close.
John Hall
Blues Creek Guitars Inc
Authorized CF Martin Repair Center
president of Association of Stringed Instrument Artisans
http://www.bluescreekguitars.com
MaineGeezer
Posts: 1711
Joined: Wed Aug 13, 2014 12:14 pm

Re: Nut File Selection

Post by MaineGeezer »

You do need a slight amount of clearance. I find if the slots are exactly to size,the strings will bind.
Don't believe everything you know.
Anything is possible if you don't know what you are talking about.
When things are bad, try not to make them any worse, because it is quite likely they are bad enough already. - French Foreign Legion
Kevin Sjostrand
Posts: 3712
Joined: Sat Feb 09, 2008 8:06 pm
Location: Visalia, CA

Re: Nut File Selection

Post by Kevin Sjostrand »

I guess I'll say it too
You want to use a slightly Bigger file than the string size. If the string is .012 use the .017 file, etc.

Keep in mind you will probably be trying different string over the life of your guitar. Extra lights. Lights, medium lights, maybe even mediums. You should plan accordingly and make each slot a few thousands bigger than your strings. For Lights I use the .017 file. The string is .012.

Make sense?
Stray Feathers
Posts: 677
Joined: Sun Sep 08, 2013 11:39 pm
Location: Ladysmith, BC

Re: Nut File Selection

Post by Stray Feathers »

Well, here I go, hanging my inexperience out for all to see . . . I had been led to believe the nut slot should be VERY close to string diameter. I think I have (with some trepidation) leaned more towards John Hall's "a few thou" over which works, but I still get some binding, and would be inclined to go even wider as Kevin says. I just thought it was a no-no. And for the record, I have found the blade type files to have a wider selection of sizes, but to tend to bind more, and also that the thinnest ones are quite fragile. I feel more secure using the heavier bevelled files. Maybe I can widen my tight slots a bit more . . . Thanks for input . . . Bruce W.
Diane Kauffmds
Posts: 3246
Joined: Sun Mar 09, 2014 8:13 pm

Re: Nut File Selection

Post by Diane Kauffmds »

I have a set of stewmac nut files which are, 0.013", 0.020", 0.024", 0.035", 0.046", and 0.056". As you can see, they're heavy. I routinely string light strings, unless a client requests medium on steel string guitars. I use hard tension on classical.

I can still get binding, even with light strings, so this is what I do:

1. I don't go too deep. Only ~ 50% of the string should be in the slot. (75% is pushing the envelope). If you're deeper, lower the nut.

2. When slotting I wiggle the file slightly right/left. This widens the slot a tad at the top, allowing the strings to drop in easier.

3. I use abrasive cord to smooth the slot. This is really important. You don't have to buy all sizes. I use Michell Abrasive cord #52 and #55 (.055" and .018"). Those 2 sizes will clean all slots.

Since doing those 3 things, I don't get binding at all, or that freaking "ping" while tuning, from a string that doesn't want to slide nicely.

Also, it helps to start the slot with an xacto razor saw. Nut files easily slide on the nut when you make the first cut. Razor Saws don't. Just make a shallow cut with 1 or 2 strokes of a razor saw, and you're nut file will stay right on the slot. The Saws run ~ $12 on Amazon. Replacement blades ~ $7. I think you initially get 2 blades. They last forever.
Diane Kauffmann
Country Roads Guitars
countryroadsguitars@gmail.com
Post Reply