I'm taking some time away from the bench tonight and I thought I'd post up my experiences with pre-slotted nuts, since it comes up every so often. For those of you who don't know me well, I run a small shop out of my house and do a ton of setups/repairs/mods/etc., which means I'm replacing several nuts every week. I have a stock of Allparts pre-slotted bone nuts that I bought in bulk a while back, and they're typical of the quality I would see from most vendors, which is pretty rough. (StewMac and WD have nicer looking products now, but I haven't tried them and they're getting pretty spendy.) Like any business owner, I'm always looking for ways to improve the product, decrease labor costs, speed up production time, and reduce waste. This last goal is part of why I'm still using up this old stock of nuts instead of experimenting with newer product. So here's my process: Step 1: Thickness the nut so that it's a snug fit in the slot, and radius the bottom to match the fretboard (if applicable). Step 2: Measure the fret height, and add about .012". I have a Harbor Freight digital caliper I modified for this, but you could stack feeler gauges too. Step 3: Use a stack of feeler gauges (fret height plus .012") to mark a line on the nut. I use the fancy StewMac SafeSlot clamp, but it's not worth it unless you're doing a lot of these. You could just hold your feeler gauges in place and rock them across the fretboard to do the same job. Step 4: Make a mark on the bass side of the nut that's about .050" up from the first mark, and make a mark on the treble side that's about .010" up. Connect those two lines, using a radius gauge to get the right curve. This will be the top of the nut. (I just eyeball it now, but I've had a lot of practice.) Here's where that leaves you: IMG_6506 by KokoTele posted Jan 16, 2018 at 5:29 PM See how much extra waste is above the trim line? That's why these pre-slotted nuts aren't that great. You do not want to try using a nut slotting file to file those slots that deep. It'll take forever, makes it easy to snap the skinny file, and makes it harder to keep the slots perfectly vertical. The next step is how I make this pre-slotted nut useful to me... Step 5: Using a razor saw, cut each slot straight down until the slot is juuuuuusssst below the top of your trim line. Do not cut past the lower line under any circumstance. If you do that, you just wasted the nut. Step 6: Trim the waste down to the top line. I use a narrow vertical belt sander to do most of the work (with a shop vac hooked up doing dust collection, you do *not* want to be breathing bone dust), and then finish with a coarse and then fine file. If I'm feeling confident/cocky, I'll finish the shaping and polishing now. Note: If the nut wasn't pre-slotted, here's the point where you want to mark the slots and cut them. Step 7: Reinstall the nut, and rough file your slots until the file just kisses the top of the feeler gauges. (Here's where the fancy clamp is helpful, because they're still there. It's a time saver if you do this enough.) Step 8: String it up and start the setup. When the relief and action are about right, then it's time to file the string slots to the final height. Step 9: If you didn't do the final shaping and polishing already, take the nut out and do it now. There's some debate over how deep the slot should be. If you're doing a neat job, you want the string to be somewhere between halfway and fully buried in the slot. Luthier snobs prefer slots that are half the depth of the string thickness, but I find a heavy-handed player can pop the strings out of the slot too easily that way. Step 10: Glue the nut in with a couple of small drops of glue. Doesn't really matter if it's hide glue, titebond, or super glue. Some day that slot will get a little loose, and you don't want the nut to fall out when changing strings. Here's a pic comparing a raw nut and one that's had most of the shaping done: IMG_6508 by KokoTele posted Jan 16, 2018 at 5:29 PM One other thing about these pre-slotted nuts is that they're much closer to the final thickness of the slot than the unlslotted blanks. Thickness a nut a pain in the butt and I don't have a fast way of doing that well, so these pre-slotted rough blanks are still a time saver.