Nut Compensation Jig

[ozwood]

Hi Trevor ,

Just building a Nut Compensation machining Jig , when setting the the offset , how do you establish where the Zero fret is referenced from, this maybe perfectly obvious to some , not so much me .

I have done your course , so this will come as no suprise to you

I await your modified response

Cheers,

[Trevor Gore]

Hi Paul,

I hope I'm answering your question here; if not, please re-state it and I'll have another go.

Let's assume you're doing the nut-on-a-ledge thing, which makes it easier for me to explain, because that's what I normally do. The body edge of the nut ledge (effectively the end of the fretboard) is 3mm closer to the first fret than "normal", so you can get up to 3mm of forward nut compensation. So to get back to the zero fret position means that you need to machine 3mm off the front of the nut, for that string. So to get, say, 1mm forward nut compensation, you have to machine 2mm off the front face of the nut (3-2=1) i.e. we were 3 forward, then move 2 back, which leaves us 1 forward.

So on the nut machining fixture, there is a 5mm deep slot into which is clamped the 5mm nut blank, which leaves it flush with the front face. The adjustable "pin riders" are then set back from the front face to give the right depth of cut (in our example 2mm set-back for 1mm nut compensation). I measure this using digital callipers as a depth gauge. Repeat for each string, then rout away. The pin has to be the same diameter as your cutter and immediately below it. I find that a 1/8" pin and cutter work fine.

If that didn't make any sense at all, let me know and I'll have another go.

[Dominic]

Hey Paul, be very keen to see how you built your jib, materials etc once your done. Been thinking through building one but have not worked it all out yet.
Cheers
Dom

[ozwood]

Thanks Trevor,

That has explained it nicely.

I might Disapoint you Dom, Cause I'm Going to make the steps fixed by carefully filing steps in a aluminiun block , I'll just make one for classical and one for my standard OOO S/S which I fit 12 -54
to , I am Trying to keep things simple at this stage and crack on with actually producing a few guitars, but having said that I'm still happy to post a few pic's and give you a Giggle.

Cheers,

[Dominic]

No worries Paul. Still show us your jig when done. And I'll let my design keep rattling around in my brain until that epiphany moment occurs and the pile of odd shaped bit of metal resolves itself into the correct tool. I know its in there somewhere.
Cheers
Dom

[weslewis]

here is my rather simple, but effective jig using hdpe for the guides...the four middle pieces cut to .300 wide the end ones are .400 wide to center in the 2 inch slot and give proper spacing..on a 1.75 inch nut.

[ozwood]

Hi Gents,

Mine is even more "Agricultural" but it did the Job .

[weslewis]

Trevor , what kind of setup do you use for a 12 string compensated nut????
would you also mind sharing your 12 string nut offsets???

thanks

[Trevor Gore]

Wes, as you know there are many variables in the equations and many ways of setting up 12 string guitars with different string combinations and tunings. So there is not a generic set-up in the way that there is a generic 6 string set up.

Al Carruth posted on another forum that he got great results on a 12 string using a method from the book that he talks about here and again here, which is not too difficult to execute, so I would recommend trying that method. Full description in the book, of course.

[weslewis]

I have modified my jig for more accuracy..and it works well...got that part...I have six runners on the jig for the six strings...my question is on a 12 string I would assume the octave strings are compensated differently on the g thru low e...???? do you have a jig with 10 runners ???

[Trevor Gore]

do you have a jig with 10 runners ???

No, I don't have a custom jig for 12 string nuts. I do the normal six strings then because the octave strings need less nut compensation (at least, that's been the case with the few I've done) I've cut back the "lands" using a narrow chisel. I think Al does his just by filing back from the fretboard side on the nut, much the same way as the saddles are done.