As you probably know I intonate both the nut and saddle and the result is good. Here is another idea. My question is, is this is a known or previously used method?
The edge effect at the nut makes the pitch increase more when fretting the closer you get to the nut with the same pressure on the string with the finger tip. If the height between the string and the fretboard should be lower the closer you get to the nut, the same pressure when fretting will give less of a pitch increase. The finger will hit the fretboard and don't bend and pitch up the string as much.
With a low first fret (say 0.5 mm) and a tall last fret (say 1 mm) on the fretboard and the rest of the frets following a line between the two the intonation at the nut should be better. The drawback is the need to shape every fret when you do a refret.
Another way to do it is to add different thicknessed shims between the frets on top of the fretboard, the thickest between the nut and the first fret and no shim between the two highest frets. Why not in a contrasting color with a couple of mm space around the frets to be able to grip the fret with a fret puller. Will be very visible with a cool factor like the TrueTemperament frets! A fret reset would be done as usual. Maybe the height between the fretboard and the top of the fret could be varied in a more precise way for each fret and string... lots of different thickness and sized small shims!
With a CNC it would be possible to make a "ditch" or flat area around each fret with different depth, the deepest one for the first fret and the shallowest one on the next to highest fret.
I haven't done any experimenting with it yet. I think a shim can be 0.5 mm with a fret of 1 mm height without feeling uncomfortable, the 0.5 mm difference will probably make it possible to pitch correct the note when pressing hard.
My standard nut compensation works as intended with a light touch on the strings, maybe this method will improve real life playing, at least for people who are heavy handed.
No bite on this? Well. Not surprised! Would be a fun trick to make a guitar that intonates great even when you press really hard on the strings though, but it's better learn to play soft as you should and not gripping that fretboard hard!
As a side note, working on a very strange English made 1977 Norman Wood guitar with round silver steel bars as frets(!). Secured with some glue. He used great force to press the round bars into the fretboard and he used metal feeler gauges with different thickness for each fret to press the bars into the fretboard. The top fret 1 mm lower than the highest fret and the rest of the frets in a line between. Could not understand why until I figured out that he probably was aiming for better intonation
Roger, your posts are always interesting! The English guitar sounds fascinating. Are the round bar frets pressed into a slot pre-cut for depth? That method of fret setting sounds like a step towards the holy grail of perfect intonation along the path to which you lead us in your fascinating offerings! Can you post a photo. Thanks again.
Thanks for the support and the nice words!
Well. I have a bunch of pictures of the guitar I restored and also found an article with the "mad scientist" luthier himself from an English guitar magazine from 1978. I have to say that I haven't leaned much from Norman Wood, I guess I'm a sucker for people who does things different. After all, I'm like that myself. He surely had some novel ideas and most of them at best another way to do the same thing.
The guitar had a different bracing, a variant of a fan brace . As a matter of fact almost the same bracing as John Ashborn used in the 1840s. The bottom is pretty ugly, but functional. Makes for a bigger volume in the guitar and no need for bottom braces. But the bottom was also totally "dead" when tapping.
The neck was VERY thin, solid rosewood with mahogany in the head. The fretboard a thick slab of Lignum vitae, one of the hardest woods there is. It had a thin rosewood veneer on top. The neck was pretty square and not to my liking. The frets solid round bars pressed into the hardwood with a lot of force with "nibs" on the side.
The bindings was all made of layers of thin veneer, also the kerfing. He didn't use heat when forming the sides, it's unknown how he did it. I think the sides were solid, but it may have been layers of veneer. All the marquetry was made of thin veneer.
The bridge was divided in two pieces, on this one the bridge was glued but he usually had it loose. The string pins was tilted FORWARD about 45 degrees, I don't know why!
The whole guitar except for the neck was made of mahogany including the braces on the top. It's a big guitar, 105 cm long, 42 cm wide and 10 cm on the side. It really didn't sound that good, kind of average.
The most interesting thing was the frets. As I mentioned, he lowered the frets closest to the nut, probably for intonation purposes. It's a lot of work to do the fretting another way, especially if you want to make a radiused fretboard, the one on the guitar was flat. The big mass on each fret could be good on a gypsy style guitar though, using a thick plectrum and going for maximum snappiness and volume.
Here are some slides of the finished guitar in all it's glory.
More pictures, Swedish text and the article can be found here
The ad in the magazine :-)