Selecting nut-slotting files
 

Stewmac sells 12 widths.
http://www.stewmac.com/Luthier_Tools...ing_Files.html

Here are the widths of the files in thousandths of an inch:
10 13 16 20 24 28 32 35 42 46 50 56

I don't wanna spend $165 for all 12.
This is a hobby not my profession.
I want to work on my own guitars which have lights or extra lights with the following gauges:
12-16-25-33-43-53
11-15-24-32-42-52

Even if I bought all 12 files they still don't all match the strings I use.

Whadyado?
Do you use, for instance, a 0.010 file for a 0.012 string but wrap the file in, say, 800 grit sandpaper?
Should the string fit tightly in the groove, or is it best to have, say, 0.001 of space on each side of the string?

IOW which files would you buy for ONLY the above string gauges?

Next, since the cutting surface is curved not flat I assume you could not save money by not buying a few sizes and instead clamping two smaller files side by side.
For instance ...

56 = 32 + 24
50 = 24 +16 + 10
46 = 20 + 16 + 10
42 = 32 + 10

Am I correct in assuming it's important the bottom of the groove is curved with a radius that matches the string for better contact and longer wear?

This question comes up semi-regularly.

If you want to save money, buy a set of $10 needle files and a $10 X-Acto saw. You will then be able to accommodate all string gauges. I used those tools for more than 25 years quite successfully. Luthier's have used similar tools for generations.

Gauged nut files are a relatively modern invention. They are convenient and nice to have but not essential. They save time if you do a lot of this kind of work.

If you start trying to double up files to create wider slots you will negate the ease and speed that comes with using gauged nut files.

A narrow nut file can be angled side to side as you file in order to create a wider slot. However, if the file is significantly under size, that too negates the effectiveness of having a gauged nut file. It is then just as easy if not easier to use a needle file. Getting a gauged nut file to cut .005" larger than its size is pretty easy.

Opinions very on how important the shape of the bottom of the slot is. I have found no difference between a round slot bottom and a flat slot bottom.

For speed and ease of use, these days I prefer gauged saws, which leave a flat bottomed slot. Unlike files, saws cannot very effectively be made to cut a wider slot that it's blade.

From Stewmac's selection, for your string gauges, on a budget, I'd buy .020" and .025" saws and .035" , .046" and .056" files.

You might want to consider these: http://www.japarts.ca/Uo-Chikyu/Uo-C...s-Featured.asp

I've done hundreds of nut slots using only a German-made Blintz back saw that I purchased 30 years ago; it's somewhat comparable to the small X-acto hobby back saw.

I use only the fine blade that came with the interchangable blade set (somewhere around .015") and rock the blade to the side for wider cuts. All my slots are finished off by wrapping a sheet of 220 around the bottom of the correct sized strip of metal that works with the slot size I'm working with. The strips are available in finer hobby shops, and come in precise thicknesses. I keep a bunch of these handy, and even round the edges and mount them in handles to create "Special nut slotting tools".

The smallest slots are simply smoothed and rounded with a folded piece of 220 directly in the slot created by the back saw.

It might seem that a thinner saw is needed, but I've never experianced any difficulty with slot width, as the rounded bottom of the slot prevents the string from buzzing if there is sufficient back angle, which should be the case in a properly formed slot.

There are a lot of "specialty tools" being marketed to those who didn't cut their teeth on older methods. No problem with purchasing specialty products, but I feel it's far better to learn to use tools and techniques that are adaptable to many situations.

Many of the "specialty tools" elict amusement to me, as I see tools that were created for other purposes, re-branded as 'guitar tools" and sold at a substantial markup.

A luthier supply shop owner has to put food on the table somehow...

A final tip... Pay particular attention to ANYTHING Charles Tauber posts!

The bottom of the nut slot should not be a semicircle the exact same diameter as the string. That will cause unnecessary friction when tuning. You really only need contact at the bottom of the string, and a slot that isn't flat on bottom so the string won't slop from side to side. The bottom of the slot can be a semicircle (or some other concave curve) quite a bit wider than the string and do that.

A knife edge needle file can do the plain strings from .010" to .017". As others have said, it's easy to add a few thousandths by tilting the file a bit from side to side as you cut.

I have the whole set, but the ones I use most are: 13 16 20 28 35 46 56

I would go with - 20 28 35 46 56. Ideally you want the files to be at least .003" larger than the string.

I bought these, which are cheaper ($54 for 6 sizes - 2 per file). They were fine for my amateur work. I could have used needle files too, and I respect Charles' comments. I do like having the calibration.

http://www.philadelphialuthiertools....e-set-3-files/

As always, not the tool, but the technique. Whatever works for you to make the appropriate rounded slot is what you use. Me, I use five files plus the skinny saw blade for the smallest unwound steel strings.

Here's my current setup, five files joined at the hip:

http://www.frets.com/ForumPix/nutfilefan01.jpg

Makes a nice one-handed tool, quick and efficient for me to get the job done:

http://www.frets.com/ForumPix/nutfilefan02.jpg

The exact gauges aren't all that critical for me, as I use a "rolling" motion to widen the slot a bit as I cut it lower. With those blades, I manage to fit most any strings, up to mandocello. I rarely work on basses, so I'd probably reach for something bigger more often if I did.

Too often we believe the advertising that suggests you must have a specific tool to get a job done. . .

That's very kind, but that's how I feel about Howard and Frank.

I also have a couple sets of the hardware store needle files. Between the 6 I've been able to do slots on electric and acoustic. I start the wound strings with a razor saw, and that saves my files and hand a bit of work.

I suppose if I did enough of these a gaged set would be nice, and Frank's idea is nice. Just wondering if you were able to use a regular HSS drill bit or had to use an endmill?

After 20 years of using regular needle files I finally upgraded to diamond grit needle files. I still just use needle files.

I once read a very convincing article on the shape of the nut slot that suggested a square would be best especially considering someone who may use a Bigsbey or some sort of vibrato with a standard nut. A circle shape, the string, in a square slot will have only 3 points of contact (maybe even just two) and have less friction then a circular shaped slot that hugs the string all round.

Just thought I'd bring that up as a point of interest and discussion.

It's easier to sit on a mountain top than on a tack. :) The less the contact area the more pressure on those areas. Probably not the greatest idea. It will quickly wear the slot shape to a more rounded contour in any case.

I would tend to agree with this. I aim to make the slots "round" them lube the slot with pencil graphite.

I don't know who may also do this, but I don't follow the headstock angle when slotting. I start off with a shallower angle at the break point and "round" the slot into the angle.

I believe I read Eddie Van Halen used squarish slots when he first started out, which helped him because he did a lot of dive-bombing with the trem bar, and it was a vintage trem at that. Floyd Rose didn't come around with his locking bridge until later, and even the Rockinger needed a good nut, because it was a behind the nut clamp.

I just did some work on a friend's guitar which had really high action. High at the 12th...like a trapeze...and high at the nut too. So I lowered the saddle no problem. I lowered the nut by carefully sanding the bottom of the nut. No problem.

Then I thought, geez, those slots could come down a hair more each...so I got the 52 nut file and carefully filed a tiny bit...put the string back in place and now there's buzzing on the low E.

Talk about a fine line...I barely removed/ filed anything and it went from being clean to buzzing.

Have I widened the slot? What is likely here? It's definitely not touching any frets...it's a slot issue. Fretted at the fist there's no buzz. So it's in whatever I did with my minuscule filing.

Any tips on how to right the ship?

cheers

Did you disturb the angle of the slot, or maybe reversed it slightly? Fret the 3rd fret. If there's still a gap between the string and first fret then you're probably OK and just have to adjust the slot .