Replies to This Discussion

Permalink Reply by Tom T on March 9, 2015 at 9:59am

Hi Tom.

Is your build a fully fretted CBG or a fretless "Slider"? This will determine how critical the string height above the fretboard is. If it is a slider, height above the fret board can be relatively generous (1/8"~3/16"). You would want the nut to keep the strings off the fretboard under normal sliding pressures.

If the fret board is fretted, then "action" height above the frets is more critical. There is a lot of discussion on the board about action height, but I think the width of a dime is pretty normal for a guitar you intend to finger and slide. Action up at the 12th fret would be greater. Do a search of "action height" and you will get a lot more detail.

Remember you can juggle the bridge height and nut height with shims to until you get an action that works for your style of play.

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Permalink Reply by Tom Gilreath on March 9, 2015 at 10:17am

My apologies, it is a standard, fretted 25" scale.

I understand what you are saying about the height and I will work on getting the dime thickness height.  Thank you for that.  

I am concerned about placing the nut in the right place.  It seems to me that if I am off my just a little bit on my nut placement, it is going to screw the whole thing up.  Perhaps I am over-thinking, but I want it to be a nicely playable guitar, not just something to say, "hey, I built this thing.  Looks cool, huh?"  Haha!

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Permalink Reply by Tom T on March 9, 2015 at 11:21am

You're not over thinking it. The distance from the nut to the first fret is very important since, if it is off, every fret after that will also be off and you'll have a tough time getting intonation correct. I would not use the front edge of the nut (screw) for measuring. The strings actually contact the nut farther back than that. If you're using a standard 1/4-20 screw, I would measure from the center of the screw (when viewed from the top).

Once you get the guitar assembled and strung up, you can measure from the center of the nut to the bridge to set the scale length. Tune the strings then check tuning from the 12th fret. You may have to move the bridge a bit, re-tune and re-check to get the bridge in just the right place to be in tune open and at the 12th. Once you get that sorted, you should be in good shape at each fret. You may have to angle the bridge slightly to get all three strings in tune open and at their 12th, but that is not uncommon.

It is all easier than it sounds when you write it up.

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Permalink Reply by Richey Kay on March 9, 2015 at 7:03pm

I can't argue with Tom's advice here. My two cents would be that if you're making a fretted guitar, use something else for the nut; bone, corian, hardwood etc. so you can not only make sure the point of contact with the strings is at 'fret zero' but you also have more control over the depth of the individual slots...

I did a section on nuts in this blog post: http://www.cigarboxnation.com/profiles/blogs/4-tips-to-make-a-cbg-p...

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Permalink Reply by ChickenboneJohn on March 9, 2015 at 7:10pm

Using a threaded ror or bolt as a nut, set the scale length from the centreline of the diameter of the rod /bolt. When setting the adjustable bridge, adjust the action so the saddles are extended pretty much to their full extent, with just a little bit of thread showing thru' the front of the saddle, then measure the scale distance to where the string rests on  the "break point" of the saddle. Strings will always need a little more length as compensation, so always fix the bridge so that the strings can be lengthened beyond the theoretical scale length - they will never need to be less than the theoretical scale length.

Here's my take on action at the nut..it isn't gospel but works for me.

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Permalink Reply by Slowpaw Steve T on March 9, 2015 at 9:01pm

don't sweat it!  just place the nut / string height so you can comfortably fret the first fret, keep the bridge floating, adjust the bridge back until you can set the correct intonation on the 12th fret..  :-)

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Permalink Reply by Scott aka Farmer Ted on March 9, 2015 at 11:26pm

Agree with Chickenbone John. He makes a great observation about how to place the bridge. And spot on about the threaded rod nut too.

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Permalink Reply by Tom Gilreath on March 10, 2015 at 11:27am

Thanks, everyone for your contributions and sound (errrr...no pun intended?) advice.  Your wisdom will definitely be put to good use!

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