Tool for filing nut slots

[Stevo75]

I'd like to lower the action at the nut a tiny bit and maybe add a little with so that my string doesn't bind (tried graphite from pencil and it didn't work).

Is there a good tool for doing this? I have Rob's mandolin setup book and he suggests carving some notches into the feeler guages which are used to estimate string height above the frets but that doesn't seem like a great option. Is there anything else other than a specialized luthier tool - which I'm guessing is pretty expensive?

[tonydxn]

You can get a set of needle files quite cheaply at most tool stores. There should be something in the set that will do what you want. Go carefully though, it's very easy to go too far . . .

[texaspaul]

I use welder's tip files about $5-6 for a set at hardware stores. They are round & flexible and smooth the groves om bridge also. They will not be fast cutters so they slowly remove material less chance of taking away too much.

[billhay4]

You can make your own per Rob's book with spark plug gap tools. Just file notches in the ones of the correct thicknesses.
Bill

[fox]

Hi Steve, there are lots of DIY options but the problem with cutting a nut slot is, it is a precision job & really needs a precision tool!
I have tried most methods over the years before finally buying a set of nut files.. however as you guessed, they are expensive.
You can find very cheap nut files on eBay and the like & they might just work for you but they are really horrible to use & frustratingly blunt! You can also buy gas welding nozzle cleaning rods that can work after a fashion but they are flexible and frustratingly blunt!
You can find micro files in hardware stores but they tend to be pretty thick & only work on bass strings.

[Jeff Mando]

Really there is no substitute for a nice nut file set, but that'll cost ya $125-150. You can get by with one or two of the smaller files, like a 10 and a 13 and make up the rest with micro files from the tool stores. The in-between sizes can be made by rocking a smaller file, but the smaller sizes require having the right file.

[acousticphd]

I have an assortment (6-7) of these StewMac files ($14 each) that have been invaluable, so it doesn't have to cost quite that much.
http://www.stewmac.com/Luthier_Tools...ing_Files.html
Haven't tried the inexpensive needle files or welder-tip cleaning type. I think a few decent gauged nut files are well worth the money.

BTW, I have never used feeler gauges - In the end, what you are doing is visibly gauging a gap, either by eye or tapping the string to see/feel the clearance. Using the "fret-at-the-3rd, tap over the 1st" trick should do equally well.
The real key is to go slowly and carefully; the files do not pass through the slot with the same ease as they get deeper, so you need to be really careful not to bear down too much, and check the clearance every couple of strokes.

[John Kelly]

I would go with the suggestions of getting the proper files if you intend to do more than one set-up. I have tried the feeler-gauges and other cheap substitutes but since getting some of the proper tools the job is just so much easier.

Remember too that the slot you are filing needs only to be deep enough to accommodate half the diameter of the wound strings. You will see many nut slots where the string is sitting away down in a deep slot and this can contribute to binding problems.

I use a zero fret on my own builds, so the nut is only placing the strings at the correct spacing and not setting the precise height, but on any guitars or other instruments I am setting up with no zero frets there is no substitute for the correct files.

[HoGo]

I've been using feeler gauges for years except for thick guitar strings where I use tiny tapered round files.
I never found the nut files round enough, they typically cut somewhat trapezoid-shaped notch. I nicely rounded edges of my feeler gauges and then cut tiny teeth with fine triangular file works great and leaves smooth bottom. I pre-cut the notches with triangular file and use the feeler gauge just to fit the string into right depth - usually few strokes.

[Bruiser]

You only need four files to do a mandolin; two or three if you do the rocking trick. At $14 each from StewMac, that's not a huge investment compared to paying a luthier to do it. And they will last for years.

Besides, real fret files leave a nice rounded bottom in the slot, for smooth tuning. A notched feeler gage won't do that.

I use the StewMac gages for mandos and the treble strings on guitars. For the fatter strings, including a five-string bass, I have a small collection of needle files that I store with the fret files.

[Woodrow Wilson]

another vote for the welders tip files.. wide spectrum of sizes and you're only spending a few bucks. They worked a charm on my cheaper Washburn guitar and my Washburn mandolin as well as my niece's baby sized Luna guitar. I ran out of luck when I tired to file the denser bone nut on my Larrivee. They work well on plastic nuts but bone is a bit more of a headache. As others have said, be careful, I got carried away on the first guitar and need to replace the nut when I have a chance. Ideally, I'd love to have a set of dedicated nut files but it's out of my budget for now. They're definitely worth it if you plan to do this more than a couple of times.

[Stevo75]

Thanks for the info everyone. I'm not a luthier and I'm not planning to do this more than I have to. On the other hand, I have two mandolins and they're probably going to need some nut work every now and then. I hate bringing an instrument into a luthier for something a simple as adjusting a nut slot, so I suspect I'll need to do this more than one time.

Anyway, I'll look into the welder tip files and also into getting a set of real nut files if it seems the welder tip files won't work for me. Quick question, if I were to order nut slot files from Stew Mac or something similar, do I order the size that matches the string I'm going to use? For example, would I get a .011 nut file for the E string, because that's the diameter of the strings I use, or do I need to buy a nut file that's larger? Do they label the nut files to match the string size (i.e. a .011" nut file is used for a .011" string, so the file itself is slightly larger)?

[kkmm]

The feeler gauges work OK for me, not the best. Have anyone thought about using a short piece of string itself held both ends by an U-shape thing as a "saw" to file the nut slot for that string ? This method would only work for wound strings of course.

[EdHanrahan]

... not a luthier and I'm not planning to do this more than I have to.

Yep, that's what I thought once upon a time. Then you try your buddy's instrument and find yourself saying, "Uhmm, this could play a bit easier if ...". And you're happy to have the files, and a bunch of gratitude, once again.

I'm no professional but: IMHO, an .011 file would probably work okay for an .010 string up thru .013 or maybe a bit more. Just rock it as you file to widen the gap just a bit.

ALSO helpful (and not just 'cause I'm now 70!): A pair of cheapo but high-number reading glasses. Now using a +3.25 pair, and the level of detail at 4" is most impressive. Wouldn't want to read that way, but for nut / bridge / fretwork, they're most helpful.

[EdHanrahan]

... U-shape thing as a "saw" to file the nut slot for that string ? This method would only work for wound strings of course.

Yeeeww! IF the windings could actually saw into any self-respecting nut (that is, o/t the cheapest, softest plastic) imagine what they'd be doing to your fingers!!

[multidon]

It is a good idea for your slots to be a couple of hundredths larger than your string diameter. The files are marked with their exact size and are not meant to literally match the diameter of the string. I would use a .013 file for .011 string, for example. .012 might be ok, just a hundredth for the solid strings. Definitely 2/100 bigger for the wound strings. .040 for .038 string, for example. You don't want to go much bigger or strings will buzz. If you do exact size, like .011 for .011, strings may bind in the slot.

[HoGo]

You need to round the edge of feeler gauges to get rounded slot. It's easy to do and they DO work nicely. Sharpening them is easy, too. You can put hem in a vice and cut tiny teeth in all gauges at once.
I polish bottom of problematic slots in pearl (sometimes they are kind of gritty rough) with 1200 grit sandpaper wrapped around edge of feeler gauge (rounded). My typical sandpaper measures a bit less than 0.2mm folded so with 0.1mm gauge it makes perfect tool for polishing bottoms of e slots and with 0.2mm for a strings. I wrap fresh part of paper for each slot and few strokes do the job. you can get really shiny bottoms this way for better sting sliding through slots.

[Stevo75]

What about different string sizes? Sometimes I use J-74s and sometimes I use sets with a larger A/E string.

In other words, if I go back and forth between .015 and .016 for the A string, and .011 and .0115 for the E string, to I fit the slot to the smaller or larger string?

[Larry Simonson]

KKMM above wrote "Have anyone thought about using a short piece of string itself held both ends by an U-shape thing as a "saw" to file the nut slot for that string ? This method would only work for wound strings of course."

I have done this and I'm not impressed. I found a bent up set of 6 guitar tuning machines in a Guitar Center parking lot and cut them into individual machines and made up four gadgets to hold a string tight using them. I roughed up the tight strings with course sand paper and they will cut the bone slowly.. The problem is that they cut deeper on the leading and trailing edges of the bone so that the groove has a high spot in the center. I think the same thing happens with those gas orifice cleaners. I believe the leading edge (next to the feet board) should be the highest point of the groove so I now use roughed up feeler gauges.

[kypfer]

Shock - horror!! I use a serrated bread/fruit knife for the thin slots and an appropriate hacksaw blade in the thicker slots. I've done several guitars, a banjo and a couple of mandolins like this with no problem. The only provisos are:

1) Work very slowly, one light cut at a time
2) Have a metal "guard" in place on the fretboard, against the nut, of an appropriate thickness to prevent going too deep. A feeler gauge or even another hacksaw blade works for me.

Any unfortunate errors can be resolved with a drop of superglue and a strip of thin plastic in the slot.

[multidon]

One important correction to my above post. I meant to say, make the slot a couple of THOUSANDTHS larger than the strings, not hundredths. My apologies. I should not post when I am in a hurry!

I would size the slot to the largest gauge string you plan to use. If you go the other way, they could bind. I don't think one or two thousandths difference is going to make the smaller strings buzz.

[John Kelly]

KKMM above wrote "Have anyone thought about using a short piece of string itself held both ends by an U-shape thing as a "saw" to file the nut slot for that string ? This method would only work for wound strings of course."

I have done this and I'm not impressed. I found a bent up set of 6 guitar tuning machines in a Guitar Center parking lot and cut them into individual machines and made up four gadgets to hold a string tight using them. I roughed up the tight strings with course sand paper and they will cut the bone slowly.. The problem is that they cut deeper on the leading and trailing edges of the bone so that the groove has a high spot in the center. I think the same thing happens with those gas orifice cleaners. I believe the leading edge (next to the feet board) should be the highest point of the groove so I now use roughed up feeler gauges.

Larry is right about the string as a slot file. I tried this a long time back by putting a length of string into the frame of a jeweller's saw and tensioning it as much as I could, but even this still gave a bit of sag in the string, resulting in the higher mid-slot problem Larry mentions.

[Paul Hostetter]

Really there is no substitute for a nice nut file set, but that'll cost ya $125-150.

I think there is. I had to learn all this long before those nice nut file sets were even on the market. Have a look here.

At the very bottom of the page is a link to another page on the general topic of slots that I think many will find helpful.

[Willie Poole]

Like Texaspaul posted, I use the welders tip cleaners, they don`t cut a lot of material all at once so you can take your time and do a very neat job, there must be 20 files in the set so you check which cleaner is just a tad larger than the string that you are slotting for...The best thing is that they are real cheap in price...

It`s worth the 5-6 bucks to see if they will be to your liking....

Willie

[Paul Hostetter]

It's worth the 5-6 bucks to see if they will be to your liking....

I tried 'em, a couple of times just to be sure, and I hated 'em.