discussion of intonation

[tippie53]

these is a lot of discussion on this topic and I would like other experts to chime in

Through the years we seen changes on the saddle angle. Martin in the early days of steel used a flatter angle and now its about a 3 degree , and gibson was a touch more.

So how can you determine the proper angle for your guitar? Remember that the compensation for intonation is based on scale length. The string to string intonation is based off string gauge .

I like to think first of the Variables we face.

A The action height
some player like higher action than others so the higher the action the longer the compensation length
Neck relief , A the neck curves again this requires more length
Top bow this is a guess to a degree as RH will also have something to say on how the top reacts and again
higher sharp lower flat
Bridge twist as the bridge loads the saddle will roll forward and again this creates a sharp condition
Players style some are aggressive and play with a tight fretting hand
Age of strings work hardening will change the strings characteristics


so now , how can we control all this?
The key is how you set the saddle on initial set up. Know that in the end all of these variables create a sharp condition. How much is as individual as the player. So I have been using a .100 inch wide saddle and I know some go as much as 1/8 inch , so with a 3 degree slot on the bridge you have some room for working the length of each string to dial in the compensation. I also shoot for .150 to .180 saddle height off the top of the saddle. Know that in the summer , the top may rise and drop in winter so a lighter braced guitar may need a winter and summer saddle.

I make my bridges .400 in high to start. When I set a neck I am looking at .375 in height at the top , on the line of the saddle. So when I set the bridge I shoot for this height. Now I can assume ( I know this is dangerous ) the top rise may be about 1/16 of an inch. So that will take us to a .325 height on the saddle for the initial set up.. This can change a bit so if you get close just remember to be about 1/16 off the bridge. Too much and you have too high a saddle and too low not enough.

Once you get the saddle height and set up allow a few days for the guitar to settle in. It is not uncommon to see changes in 3 to 14 days. The top will come up and bridge will roll a bit. I like to see a few cents flat on initial set up because I know things will go sharp during settle in. Don't touch the saddle yet but after settle in time you can now address the saddle for final intonation adjustment by tweaking the saddle on each string.

there is nothing magical , its all physics. Learning these skills are part of the trade. The better you can set up the more work you get. I am sure you noticed that in the end , its always just how long does each string need to me. All the variables have a tendency to make stings play sharp so learning how to dial that in is very important.

[rcnewcomb]

Thank you for the clear explanation.

[Kevin Sjostrand]

Wow John
Great info. I do consider some of those things but I had not really thought about all these areas that do affect intonation.
I like a 1/8" saddle so there is some room to play with it.
Thanks for bringing up this subject.

[krrtlr1]

Interesting info John. Like we say in the trade, the numbers never lie.

Thank you for sharing.

[TEETERFAN]

Thanks John. I’ll be adding that post to my permanent notes!

[Diane Kauffmds]

I've never actually measured the eventual height of my saddles. I set them higher, then dial in the eventual height at setup. I seem to have hit on a perfect string height that both my fingerstyle players, and bluegrass players love. Although guitars are known as imperfect instruments, the intonation is almost spot on, all the way up the neck. I'd be willing to bet that my saddle height equals what you've laid out. I'm working one handed right now, but I'll see if I can't pull out a couple of guitars and check.

I actually just use the templates in my shop to mark the eventual saddle slots, for the Martin short and long scales. If I'm making a bridge for a differing scale length, I do the scale calculations, then draw the saddle slot line on the bridge, after it's glued to the guitar, and I rout the line.

New setups always need tweaking in a couple of days. I always tell my customers that it may change further when they take their guitars home, because most don't have the climate control that I keep in my shop.