Official Luthiers Forum!

In buying files do I need to match the exact diameter of the strings and then polish with abrasive cord to get the most professional results?

Am I over killing the results required at the nut? Are Grobet's files worth the $30 each price tag?

Thanks,

-jj

No, yes
No, maybe, but not to me.

That is, you don't have to have nut files for each string diameter, you can use old strings or abrasive cord.
You can't overkill the requirements at the nut, it's one of the main ingredients in playability, and is almost always left too high.
I've made about 20 guitars without dedicated nut files, so I have no idea if the files are any good, but I don't have to spend that kind of money to get acceptable nut slots. I'm sure they would make the job quicker and easier, but as an amateur I can't justify that expense.

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A man hears what he wants to hear, and disreguards the rest. Paul Simon

I think that string slots should always be slightly wider than the given string, not only because that allows for some variation in string thickness but it also permits somebody to put on heavier strings if they want to. I have a set of seven or eight files, and just use the one that's one size up from the string. No problems so far.

And I'll agree with Roger that time spent on the nut is time well spent. Frank Ford's FRETS site has great advice on how to make nuts, if you haven't visited it before.

You don't need a set of 20 nut files. I have 6 and for years I've made do with only 4. 2 or more strings can share a nut file, it can be a little too wide, and if it's too small you can wiggle the file to increase the slot size.

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Cat-gut strings are made from kitten guts, stretched out to near breaking point and then hardened with grue saliva. As a result these give a feeling of Pain and anguish whenever played, and often end up playing themselves backwards as part of satanic rituals.

Typhoon Guitars
http://www.typhoon-guitars.com

Roger is right that the nut is pretty important not only to playability but also to tone and this is not an area to take short cuts.

I have likely 30 or so gauged files and our business has at least 3 times that many. Why? Because doing superb work is our passion and we will not be cheap or incomplete when it comes to our value proposition AND results for our clients.

Grobets are great, Stew-Mac gauged files are also great. We've used them all and researched how they cut as well and posted in various places about this prior. We've also been beta testers for Stew-Mac when they revamped the gauged files and changed suppliers, the current offerings are excellent, very close to or equal to Grobets and less expensive.

The reason why I may need as many files as I have is that we work on any plucked, stringed instruments including basses, mandos, B*njos, and all of the variants as well. Someone may be able to cut a .105 slot for a bass with an x-acto.... file but the workmanship would not be up to professional standards.

My suggestion is to get 6 files from Stew-Mac for the gauge of strings that you like on an acoustic guitar. That's how I started. But you know too JJ a lot of the answers that you may receive and the quality of same is also very dependent on things that we can't know. For example is this first guitar going to be it or will you build only a couple guitars. You can get by with less if this is the case AND if you don't intend on any commercial presence where professional standards come back into play.

Abrasive cord is not recommended because it has a tendency to flatten out the slot at the nut face and exit. This can cause a sitar sound. Instead, if binding is the issue for say a .013 high e string nut slot with a .013 string gently scraping the nut slot sides with the file as it approaches the bottom will gently widen the slot. A properly sized slot will not bind so no need to polish the bottom of the slot.

If you have the coin and inclination Grobets are excellent and they most certainly are worth that price to me and we have many of them too. In my world we will see over 1,000 instruments in our shop for repair annually. Most of those will have nut slots cut or cut correctly for once.... since the f*ctories never deliver any instrument with properly cut nut slots. This means that we may be cutting several thousand nut slots annually. This is why Grobets and Stew-Mac files in all available gauges are a good fit for us. It's also expected since we are pros who are trusted with the valuable personal property of others, a bailment too if you will, that we will go beyond ordinary care as the legal standard in how we approach being tooled up as was well as the standards for quality that we subscribe to. One of us is also wrapped too tight as well...

Anyway this is why you are getting various answers that are not in agreement. Personal and professional standards may vary and for some of us the expectations since we are in the biz are substantially higher than for the average hobbyist.

So you might want to do the first guitar with the minimal tools required and see how you like it. That way you won't be one of the good folks selling entire Lutherie shops in the OLF classifieds and save some money too. If on the other hand you know you are hooked - go for it - good tools are a passion of mine as well and I never bought a quality tool that I was sorry to have purchased.

Cheapest way is to buy a very fine tipped round Grobet needle file. Very easy to break the tip if you apply too much pressure. That's pretty much what everyone used before the gauged fret files became available, it does take a bit of skill to use it right though. The other alternative is a Pippin file but I haven't seen a decent one of those for decades, certainly not the one that LMI stocked.

Needle files are not fine enough nor are they consistent through out the stroke meaning that they produce slots that are wider at the end that the file was used from. We see lots of parts guitars.... even though we would care not to... and it's often the case that the builder used needle files. What results are slots much larger than what's needed for some individual strings as well as inconsistent slots as well. It's often the case that the nut that came in with the instrument gets pitched.... and we make them a proper one.

I've not seen a needle file including Grobets that are capable of making a consistent .0125ish nut slot which is standard fare for lights on acoustic guitars. Nut slots should not be much larger than the intended string gauge AND if building to sell to a yet to be determined buyer nut slots should, when appropriate for the instrument..... be suitable for one gauge up as well. More specifically if building a dread it's possible that the purchaser would use mediums so the slots would be cut for mediums but suitable for 12"s or lights. This means that the high e slot on this dread would benefit from a constant .014ish slot. Needle files are too thick to produce even a proper slot for mediums for the high e and likely the b as well.

Nut slots are not just another pretty face and they can be difficult to master and do well. It's often the case that they are cut with a hump in the slot too making it important for the tool used to be predictable, be straight....., and cut consistently so you know what to expect when getting close to the point of no return.

IME nut files are not where to cut corners because alternatives will not produce acceptable results.

The round needle file will only cut tapered slots if you allow them to. That's where the skill comes in. In fact I can get the same needle file to cut slots that flare in, slots that flare out, slots that are parallel. . . and that's with filing from one side of the Nut!
As I said, pretty much everyone used the round needle file before the gauged files were available, both Violin and Guitar makers.