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StewMac sends their kits out these days with 'pre-slotted' nuts (see pics). Sounds great, eh? But if you just use them as delivered the string action ends up being massively high at the first fret. I didn't realize this on the first guitar I built and just glued the thing in place and strung it up... but then I ended up filing all the slots much lower later on to get it to play properly (and then reshaping the entire top to match). Didn't seem to be how they intended for these things to be used. So my question is, what are you supposed to do? Do you file the bottom off so that the pre-cut slots sit at the right height before installing, or just do as I previously did and re-shape the whole top later on?

Some pics:

My guess would be the manufacturer intended that you fit by sanding the bottom, then make small adjustments to the slots and top crown in your final set up.

A nut has a couple of required items - two are the string spacing and the slot depth. There are common string spacings and SM is giving you that, but there is no way they can guess at the slot depth because every fret job is a little different. I think it should be expected that you would need to adjust the depths to get a good job. Unfortunately, a set of nut slot files is an expensive tool, but if you have the slots started and the right width for each string, just lowering them with a needle file is not too hard or expensive

the slots are pre spaced but not to depth. Nuts are very important in the guitar. If you plan to do this invest in a set of nut files. I learned early this is one tool that is in the need list.
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Martin is using gauges blades in a jewler saw ,
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Thank you for the replies, much appreciated! I guess there is no 'trick' involved in fitting these, they just have to be regarded as roughly finished at best.

Seems like such a waste of time and effort on someone's part, though... they are beautifully formed and polished both on top and bottom, but if you use the nice 15 degree cut on the bottom as-is you will end up having to totally obliterate that nice smooth top in order to get it down to where it needs to be to actually play in tune. Pics included below to show what I mean. The bottom of the groove for the low E string is 0.125" above the fretboard with the nut seated in the slot, the high E is closer but still way too high as well. Cut the slots to the right depth and the strings are totally submerged in the nut... which leads to taking lots of material off the top to make it work. C'est la vie though, I guess you gotta do what you gotta do... :-)

Oh, and before anyone points it out - the nut isn't seated properly in the neck in those pics. I just popped it in for some pics and didn't notice that I hadn't pushed it in all the way. So the 'tilt' isn't as extreme in reality as it appears in the photos. But it's still quite substantial (and very obvious) even with the thing seated properly.

Andy Mitchell wrote: ↑Mon Jun 07, 2021 7:50 am Oh, and before anyone points it out - the nut isn't seated properly in the neck in those pics. I just popped it in for some pics and didn't notice that I hadn't pushed it in all the way. So the 'tilt' isn't as extreme in reality as it appears in the photos. But it's still quite substantial (and very obvious) even with the thing seated properly.

Glad you pointed that out, because that's immediately what my eye went to. Haha

There's a back story as to why that wasn't sitting quite right in the pic - it isn't the actual nut that I'm eventually going to put in that slot! It's a 'back up' that I bought to eventually replace the one I butchered on my first guitar. And it's just a hair thicker than the 'real' one I plan to use here, so it wouldn't drop in neatly like it should.

I slotted and filed the top of the nut on that first guitar after it was already (very generously) glued in place, and the profile didn't turn out as well as I would have liked. Hence my interest in how to do the job right this time around. I'll definitely be doing all of the required fettling before gluing anything in place this time.

But I have something else puzzling me as well. My OM neck measures 1.77" edge-to-edge at the nut as built, but the pre-slotted nut they sent with the kit measures 1.841". No big deal, I can knock the extra off easily - but did they really mean to send that one or was it a mistake? And (if it's a mistake) could using it give me disastrously wrong E-to-E string spacing? I already have that spare 'dread' nut I used for the pics (which measures 1.73" edge to edge) that I could substitute, but it has different string spacing. The E-to-E string spacing on the OM kit nut is 1.54", the spacing on the dread is 1.43. Just eyeballing it, I think the wider spacing would work fine, but the strings would end up pretty close to the fretboard edge. Which option do you think would be best? I'm leaning toward the wider one cut down, but really am out of my depth trying to decide.

Here's the two of them side by side, just so you can see the differences I was talking about first hand.

This is where you can personalize a nut. In general, the E and e are centered 1/8" from either edge (of the neck, not the too-long nut), then you space the other 4 strings based on those 2 end points. However, some people like extra room at the E for bending up, and some people like extra room at the e for bending down, and that will change the end points.

Then there is the discussion between even center spacing of the strings (easy to do) and even spaces between the strings (not so easy without a dedicated rule).

Then there is the discussion about the angle of the ends of the frets - I was at first told the fret ends should be 30° off of plumb and did my early instruments with a block I cut to mount the file in, but since then, I have seen discussions on professional forums that seem to center around 20° - the difference is more flat area on the top of the fret for more bending around - they call it "real estate".

A suggestion: Temporarily put the pre-cut nut in place so the E and e are in the right places, evenly in from the ends, mark the ends and cut off the excess so it is the right length. Now determine how much of the bottom of the nut must be removed to leave the slots .01 higher than they will end up - several ways to do this but I use the half-pencil method. Remove that amount. Now use some sort of narrow file (or even invest in a set of nut files if you will be doing more) to lower the slots one at a time to the right spot.

On your first couple of nuts I might leave them a touch high rather than play with fire and get one too low