Cutting Nut & Bridge Grooves (Slots)

Eldon Cangas · From: Ontario, Canada

On the heels of ""Is there a "standard" nut size, string height, etc"". I mounted 2 old guitar tuning machines 5 inches apart on a 1/2 inch x 1 inch x 10 inch long stick. I then strung a piece of plain guitar string on it and used it like a saw. It cut the aluminum bridge well although slowly and I now have one slot cut on my nut. I tried a wire wound string and it cut faster with the same result a nice nut groove. I thought I had a tip cleaner but didn't this experiment worked real well.

Blake Wilson · From: Boulder CO, USA

Nice idea, Eldon.

Regards,

Blake

David Doggett · Posted 18 Sep 2008 10:41 am

Probably a better way to do this is to use a small triangle file. It will cut metal, bone, or plastic nuts easily and quickly. You will get 45 degree V grooves. This is an ideal groove shape, because it only touches the string in two places, thus eliminating the risk of buzz from a groove that is too loose, which is always a risk when cutting U-shaped grooves. A V-shaped groove also makes it easy for you to cut each groove to a different depth to accommodate the different string gauges, while at the same time allowing you to manually adjust the depths to get the strings to line up in a straight plain across their tops. Lining up the tops of all the strings in a straight line helps prevent bar rattle at the first fret, and also allows you to slide the bar behind the nut and back onto the the frets without bar rattle.

Another advantage of V grooves is that there is very little effect when you change string gauges. With U grooves, you can end up with a groove that is too narrow for the new gauge, causing the string to sit too high; or it can be too wide, causing buzz. With a V groove, a slightly different gauge will sit at a slightly different height in the groove, but the change is so slight it will not seriously mess up the straight line across the tops of the strings.

You can also get files that have an angle less than 45 degrees. These will look a little neater, because they will more closely fit the string. But otherwise, they work the same.

They make sets of gauged files for various shapes of string grooves. You might be able to find them at a large stringed instrument dealer, such as Elderly. But if you use round ones to make U grooves, they must match the string gauges precisely, and you may be limited in changing string gauges. The simplest method is to use a triangle file.

Good luck with your project.

Bill Creller · From: Saginaw, Michigan, USA (deceased)

Stewart-McDonald has the files, but they aren't cheap by any means. If Eldon's system works for him, and it's only one guitar, the files aren't worth buying. They also aren't available for every gauge a steel guitar uses.
The auto parts stores and Harbor Freight have sets of fine files in various shapes including the kind that will make a V groove, if it does the job. They are cheap files but seem ok for misc jobs.

Rich Hlaves · From: Wildomar, California, USA

Hi all,

I have a set of files from StewMac and really like them. I bought the set/files that are double sided so you can cover two slot sizes with one file. Bill is correct they are pricey but I tech guitars on the side so it was worth the investment. (more than the cost of a budget home brew steel for sure). Their (StewMac) string spacing guage is really handy for slot spacing as well.

I disagree with the V slot vs. U groove causing buzz. Yes that is possible but if the string slot is properly made with its highest point at the fretboard side of the nut, buzz is not happening with the amount of tention put on a properly guaged string set on a steel. The same buzz can be had with a V slot if not angled back toward the tuners. V slots also wear more when changing strings and tuning. They will eventually become U shaped at the bottom and sink in the nut.

The trick is to get the slots to the proper depth so the strings are very level and the tone bar frets all the strings with even pressure. A little extra time spent here will get you much better/smoother playability near the nut.

Eldon, you're home made slot saw is priceless. Great idea!

Best,

Rich

David Doggett · Posted 18 Sep 2008 2:15 pm

Rich's points are well made. He probably knows more about this than I do. I just meant to point out that for one-shot home projects, a single inexpensive triangle file from a hardware store will do the trick, and this method is very forgiving in terms of getting the gauges just right, and also very versatile when experimenting with different gauges of strings.

Rich Hlaves · From: Wildomar, California, USA

David,

Absolutely, for a single low cost guitar, the triangle file will do the trick. My main point which may not have come out well was the angle of the slot. The shallow end must be at the fretboard or it will buzz. The smaller the string the more likely. I appologize if I seemed to slam your method.

Best,

Rich

David Doggett · Posted 18 Sep 2008 3:36 pm

I didn't take it as a slam, Rich. You're educatin' us. I learned something. I hadn't thought about the angle of the slot, but now we know how to angle it properly - shallower at the fretboard side. Thanks. Smile

Bill Creller · From: Saginaw, Michigan, USA (deceased)

One of the problems I almost always have is getting the string buzz or "wolf tones" out of the bridge and nut slots. I still have to fool with that problem sometimes.

Eldon Cangas · From: Ontario, Canada

Thanks for weighing in guys more heads are always better than one. I'm expecting that this will be my "good" guitar. I have time (winters can be long here sometimes) and plenty of stock to experiment a bit V groove vs U groove. I can't justify the price for proper files I'd rather spend the bucks on tuning machines. Another lesson learned the easy way shallow end on the fretboard side.

Warmest Regards! Eldon

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