Solving the sharp intonation on the 6th string

One of the things that has troubled my friend Ray has been the fact that his Martin plays rather sharp on the 6th string. He generally plays in a dropped D tuning, with light strings and high action. He spent a fair chunk of time in the past trying to correct the problem with compensation at the nut. He was able to make his B string (2nd string) intonate perfectly, but the 6th string always played sharp.

My original thought was to drill a hole through the pin sideways, and then run the pin backwards in the hole and over an additional piece of bone glued behind the saddle, acting as a new saddle. But when we measured the amount of out of tune-ness and calculated the additional length needed, we ended up on the edge of the pin itself.


We solved this problem on Tuesday by making a new saddle and a really interesting pin. There was a lot of discussion, back and forth of ideas, and lots of using files and sandpaper, as well as some rather nice needle files. This is what we ended up with.

Cool, huh? We added almost a quarter of an inch to the string length, and now it intonates almost perfectly. Before, it was about 10 cents sharp at the 12th fret compared to the harmonic, and now it is about a half cent flat. We could use a hair less length, but it is perfectly functional at this point. Even better, Ray was able to capo at the 9th fret and it was still perfectly in tune. AND WE DIDN'T HAVE TO ALTER THE BRIDGE! This is a big deal - I would hate to take the time to remove the bridge, plug the holes, carve a new bridge, place new saddles, etc etc.

Unfortunately, I took very few pictures of the process, so I did it again today with my Guild D25M, a nice guitar from 1977. It had roughly the same problem.

The is the harmonic at the 12th fret. I'm 12 cents flat.

And when fretted lightly (no stretching or cheating allowed), it is 7 cents sharp. That's 19 cents total playing sharp!

I start off by chucking a piece of bone on the lathe. The blue tape is there so that I feel the tape spinning by before I rip my knuckles off with the sharp edges of the chuck. I have a pin to compare my progress to.

I turned using a rasp to rough the blank, then a skew chisel and a couple of files to refine the pin. I'm getting close.

A flat mill file really keeps things from getting out of control.

Almost there.

Oh yeah, looking good. I think I might leave it like this. It looks like my guitar is flipping the bird.

Okay, fine, we cut off the extra material. This vice is from OSH, I think it's a Craftsman vice, I want to replace the jaws someday, but it is really great for making nuts and saddles.

I rough in the slot with a hack saw. I had a slightly flat spot on the pin, which made this a LOT easier.

It doesn't have to be perfect, the files will clean this up later.

I have to accommodate the thickness of the windings near the ball of the string. Lots of filing to get that notch big enough.

I'm getting close. I've made a ramp to the edge of the pin, with enough curve that the string won't kink. It's a good fit, not too tight.

Penciling what part of the bridge to remove.

That is scary looking.

Strung up, here's the 12th string harmonic.

And here's the 12th string fretted. Just a hair flat, which is okay, that string usually goes a tad sharp when fretted anyways.

Here's the 19th fret harmonic.

And the 19th fret fretted - wow! These things are NEVER in tune at that point!

Looking good.

Looking weird.

Hah! It's a pretty weird looking fix, but it really works!

So, are there any downsides to this? Well, no. There is no additional stress on the bridge, slightly less weight, no difference in tone (which is a bit shocking to me), and the whole thing is completely reversible. Hearing the guitar actually play in tune is a treat, but it also might spoil me - we compensate in our heads for that natural tendency to be out of tune, and now that I don't have to, I'm not sure how I will feel about other guitars.

YEEHAW!!!