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o.k. so I have heard martin uses a 3 degree , and Gibson used ( or uses) a 4 degree saddle angle. since I am setting up to make my slotting jig , my question is , how do you determine the angle of the saddle slot ? thanks Jody

I use a 70mm long slot, with a 3mm back set at the bass end ... whatever angle that is, it works for me.

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Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

Jody,

I set mine up at 4mm. back from the front of the bridge to the front of the saddle slot on the high E side and 7-7.5mm back from the front of the bridge to the front of the saddle slot on the low E side. The angle is whatever that comes out to be.

thanks Tony and Robbie . so Robbie , would you use the 7.5 set back on the base side for heavier strings? thanks jody

That will work Jody. I also add 2mm to the overall scale length. With these specs I get my strings to break on the front of the saddle or slightly back. Some folks add less to the overall scale length and the break point is a bit farther back on the saddle.

Robbie , just to be sure I am following you. you take the original scale lenghth , lets say of 25.34 , you add 2 mm to both sides of the scale ( treble and bass) , then add another 3- 3.5 mm , to the bass side ,depending on whether you use light or medium strings ? thanks Jody

Jody,
I don't think of it as adding 2mm to both sides of the scale. The is only one scale length. I think what you are saying is just a different way of saying what I am saying.
So, let me say it again to try and clarify. I first cut the saddle slot. As I said, the front edge of my saddle slot on the high E side is 4mm back from the front of the bridge. The front edge of the saddle slot on the low E side is 7-7.5mm back from the front of the bridge. This is a difference of 3-3.5mm and the angle is whatever it is.
When placing my bridge I reference only the high E side. The scale length is 25.4 or 645.16mm. I add 2mm. to that and reference that measurement 647.16 at the front of the saddle on the high E side. Make sure the bridge is square and Violá!! I don't think in terms that I have added 2mm. to the base side as well but I have and then the extra 3-3.5mm of the slant of the slot. If you think like that, the actual low E string has a compensation of the 2mm plus the 3-3.5mm for a total of 5-5.5mm. The 5th string would have less than that. The 4th sting less etc. because of the slant of the slot. This can get confusing in a hurry. This is why I say I add 2mm to the overall scale length and leave it at that. I hope I was able to clraify this for you.

Hey Robbie , thanks for taking the time to clarify this issue for me ! Jody

Jody, a couple of things to consider...

The saddle is longer than the actual spread of the strings. So, if you measure the angle as a difference between the compensation for the high E and low E strings, you will get a different angle if you measure that at the actual location of those two strings at the saddle, on the one hand, or at the ends of the saddle, on the other. In other words, if the END of the saddle at the low E end is 3mm further back than the END of the saddle at the high E end, then the difference in compensation between the two strings themselves will be less than 3mm; one person's angle will also be different from another's depending on the length of the saddle (how far it extends beyond the spread of the strings).

Likewise, if you determine the angle that way, the angle of the saddle will be different if the string spacing is different. The tighter the string spacing, the sharper the angle will be.

Another interesting thing is that the difference people use between the compensation of the two E strings varies pretty widely. The smallest difference I've heard (and which I've used myself successfully) is 1.7mm. That's substantially less of a saddle angle than you have with a 3mm difference, like Tony uses - and Robbie goes as far as 3.5mm. Assuming Tony's and Robbie's guitars intonate well - and I know mine do - that suggests that there is a surprising amount of wiggle room there.

When I built my saddle slotting jig, I figured out that an average string spacing and a compensation difference between the high and low Es of about 1.75mm gives me a 2 degree angle on the saddle. I decided to go with that angle on all my guitars (for the time being, anyway), and I figure that, with the intonation of each individual string that I do by shaping the top of my fairly thick saddle, I can get each string spot on, even with a range of string spacings on different guitars. So far, so good. I do use a thick saddle (though I'm thinking of going a bit thinner), because I like the idea of more string contact on the saddle, in addition to the ample room for intonating each string.

I also put a 10 degree back tilt on the saddle, so that the force of the strings breaking over the saddle is pushing the saddle more straight down onto the floor of its slot, rather than tending to push it forward against the front wall of the slot. There are those who claim this improves sound; I haven't reached my own conclusion about that yet, but the logic of it makes sense to me, especially with regard to the use of an undersaddle pickup.

In fact, if I hadn't been designing a jig that had to account for the added complication in geometry dictated by the 10 degree back tilt, I probably wouldn't have settled on the 2 degree angle at all. If you don't use the back tilt, then making a jig that allows you to change the saddle angle from one guitar to the next is a simple matter. But making a jig where the saddle angle can be changed but the back tilt and slot depth remain constant was beyond my little brain's capacity. Anyway, I don't anticipate having a problem with the 2 degree angle, and if I do, I'll cross that bridge when I come to it.

I hope this is helpful.

_________________
Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

Yep it is not an angle it a distance variable. trying to measure it by angle just leads to headaches

Interesting Todd that a 1.7mm works for you .. I dont think it could on mine, cant explain how though ...

I have the old MIMF compensation xcel file, that calcs comp for multiscales and the like ( i ahvent used it in a while, once I got the numbers working, especially on baris and multis, had little need for it).. for a 25 .4 scale, the G string needs neg comp (ie, shorter than the actual scale length), while the low E came in around 4 mm or so ... I need the 3 mm difference, plus the 1/8 saddle to get the guitars to intonate properly - even more on baritones ( I am using 3/16 saddles here and on multis now), and of course multiscales are a whole different animal

_________________
Tony Karol
www.karol-guitars.com
"let my passion .. fulfill yours"

I cut my slots on a milling machine set a 4 degrees. It seems to work very nicely. I also slant the entire sadle back toward the end block when viewed from the side so that there is more compensation if the saddle is taller, and less if the saddle is shorter.

John

hmmm " as the peg turns " LOL still getting some very interesting feedback on this thread, thanks again everyone that has something to say about this ! Jody

I set mine by taking readings on a strobe with a dummy saddle on top of the bridge, figure how far it needs to go where, and cut it. Who needs numbers?

Actually I end up fairly consistently with the high E set back at about .100" and the low E at .170" to .185". Those measurements are to the center of the slot not the actual intonation points. This generally means the high E will would be shaped toward the front and the low E toward the back. If you set the E's on center of the slot, you can run out of room to scoot the A forward or the B back enough on a thin saddle. If placed strategically, I can't recall the last time saw an instrument where good intonation offsets would not fit within a 3/32" wide saddle. 1/8" wide saddles gives quite a comfortable buffer.

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Eschew obfuscation, espouse elucidation.

The difference between .100" and .170" - .070" - is just a hair over 1.75mm. And, as David notes, the low E intonation point will be shaped further back on the saddle.

_________________
Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

The G string needs negative compensation?? Has anyone seen that to be true in actual practice?

_________________
Todd Rose
Ithaca, NY

https://www.dreamingrosesecobnb.com/todds-art-music

https://www.facebook.com/ToddRoseGuitars/

This thread got me a bit curious, so I measured out a few well intonated guitars today. I sketched out the front line of a bridge, and marked the intonation point for each string. Then I took a straight 1/8" saddle, laid it over the points, and traced it at the steepest and most shallow angles that would cover all the points.

On a 2.125" string spacing, the steepest was set back about .160" (or 4mm) from the high to low strings, and the most shallow was a bit under .030" (.75mm). As you approach either extreme, the limitations can fall on the range of 1st and 6th offsets or the 1:2 and 5:6 offsets. Strings 3 and 4 in the middle are going to be fine either way.

Granted, this was a quick and crude approach (and the sketch is not worth posting), but I feel it's safe to say that anywhere from 1.5mm to 3.5mm will safely contain intonation points for the average guitar. So it sounds like there's a pretty wide safe range, that though appearing quite different can both contain the same set of points.

_________________
Eschew obfuscation, espouse elucidation.

very cool ! i guess Todd and David answered the question i was realy asking even though I didnt ask it ?? (huh?) If there is some room for play I guess I can (fairly) safely go ahead and pick an angle somewhere in the mid range and go ahead and cut my saddle slot, and feel confident I will be able to intonate the guitar later! thanks a bunch for the help ! Jody

Todd
I use a .125 setback with a 25.4 scale and with about .12 compensation measured at the center of the saddle between the G and D strings. My G usually winds up right on the front of a 1/8" saddle which puts it just a tad over scale length.
Terry

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It's not what you don't know that hurts you, it's what you do know that's wrong.