As a first step, for the nut I use an old blunt jigsaw (aka sabresaw) blade that I found was just a touch higher than my frets. To check, put it between two frets and get a short straight edge/fret rocker if you get a little bit of rocking, I covered one side of the old blade with masking tape to minimize the chance of scratching the fretboard. Then I hold that against the nut and cut my string slots with a junior hack saw, stopping when the blade hits the old blade. I then adjust the width of my slots as necessary. At this stage the instrument is ready for stringing up.
I then follow up with the universal third fret method on all my builds. You press down between the second and third fret. There should be a slight gap of a gnat's whisker between the string and the first fret. Old time builders tested with a cigarette paper. I just make it really really close but without touching. Given the above step I usually don't have much to do.
This is how all instruments I build from bass ukuleles to Tahitian ukuleles are set up at the nut. No exceptions for instruments needing fingered frets. Slide or fretless can be higher.
Action (at the 12th) varies between instruments from 1.5mm on Tahitian ukes to 6mm for bass ukes and in between for everything else. It is more of a taste and playing style thing. If fret noise is your thing (I call it fret growl on bass ukes) make the action lower. If your frets are a little uneven leaving the action a little high can compensate for that.
Thanks for the tip, Titch. Guess I've been pretty Damn lucky so far, using the "eyeballing and feels right" method. I like your method better. I couldn't get my first one to sound right now I know at. Thank you again.
Someone revived an old post.
On the cheap rosewood or Ebony for both saddle and nut, easy to shape and cut string slots nice warm tone.
Bone blocks for nuts work great for 3 and 4 string bridges. There is a reason guitar company's use tone wood and bone.
Bolts look great but don't transfer vibrations very well, I think in the last 7 years we have all learn this but still use them. We all have a box of old bolts.
On fretted necks use a headstock tuner to set string height, check intonation between open note and the 1st fret if they are not correct none will be. I didn't have a clue 7 years ago.