Ibex ruler observation

[gratay]

here's an interesting scenario I've just experienced.
I located my bridge with the Ibex ruler that has the compensation for the high E saddle position marked on it...which I thought would be a no brainer..

Located the bridge allowing 4-5mm of meat on the bridge in front of the saddle at the high E position..

Glued the bridge on ..no problem .. all went sweet.

I have a stewmac intonator tool which I'm using to do the intonation first and then cut the saddle slot...
I also have a good electronic tuner with +/- cents..

Anyway, string it up and find that when it is intonated correctly there will only be 2mm of meat on the bridge in front of the saddle at the high E..
hmmmm, thats strange I thought. maybe the bridge shifted during glue up. Which it didn't as I masked the location and put plasterboard screws through both E strings bridge pin holes prior to clamping.

Checked with the Ibex ruler down the centre of the fingerboard to find that its marking for string length with the compensation added is not even close to where the saddle should be for correct intonation? Its about 2.5mm out?

I know other factors come into it like string brand , gauge, action , string height at the nut( which by the way is as low as I can go without the string touching the first fret when you do the ole' fret the 3rd and press down on the first fret trick)

Has anybody experienced this scenario with the Ibex ruler..?
I'm not all that keen on the saddle being really close to the front of the bridge. But i am keen on having as close to perfect intonation..it would also be a better break angle if the saddle was where the Ibex ruler was telling me to locate the saddle.

what to do?
and what may be going on here?

cheers Grant.

[Allen]

I've only ever use the 2 Martin scales on the Ibex ruler. I cut my saddle slot before gluing down the bridge, and I try to place the bridge so the compensated length is in the middle of the saddle. Gives a bit of wiggle room on either side.

I've not had a problem with my set up so far doing this, so I'm not sure what's going on with yours.

This is the second time recently that I've heard that the Stew Mac intonation rig has caused some concern like this. Not owning one, I'm not much help here with it.

If no one can come up with a better option then I suppose that one solution is to make a new bridge that has a bit more meat on the front. Not that you really want to have to replace a bridge you've just glued down.

[gratay]

thanks Allen.
What have you heard about the stewmac jig.?.. It seems like it should work without any problems..

I may just have to go with the Ibex ruler measurements as the fret positions are exactly on and identical to the stewmac fret mitre box template for Martin 25.4" .
Ibex has worked for people for years..I just know in my head that the intonation won't be as close as it can be..
but maybe its the intonator jig..? hadn't thought of that.
cheers Grant

[Allen]

I don't think that is the jig itself, but in the manner that it's being used.

Not too long ago Martin was having issues with his setup, and Craig had pointed out some discrepancies with the compensation measurements he was getting. Both of our Kiwi mates are on a bit of a holiday over next several days, so they may not get a chance to reply to this.

Not having used one of these jigs, I'm only guessing, but I think that some of the problem arrises from nut and saddle hight. Changing the amount that the string is stretched when fretting.

[jeffhigh]

It's not going to be your nut or innottator saddle height being too high, that would make you want to move the saddle further back.
Can you measure exact distances from nut to 12th and 12th to front of bridge at e and E strings and this will make it easier to advise you

[gratay]

thanks jeff.
here's some physical measurements
from the nut to the centre of the 12th fret is 322mm
from the centre of the 12th to the front of the bridge is 320mm
its the same measurement for both E's along the string path.

heres a pic of where its intonating and a following pic of the ruler down the centreline showing where the saddle should go... the ruler location starts at the back of the 2.4mm saddle slot indicated by the intonator jig.
Having said this, the ruler would be indicating the centre of the slot I'd imagine so we are only looking at a difference of 1.2mm in where each tool is saying the correct location is?





See what you all make of this observation?
Cheers in advance, Grant.

[kiwigeo]

Grant,

The issue when I was compensating my 12 string was string height at the nut being too high.

I did my last 6 string using the compensator jig and it worked out ok.

[jeffhigh]

Hi Grant,
For this scale length you would be looking at added compensation of 1.7 to 2.7mm on the high e and 5-6mm on the low E. (based on the Stewmac fret calculator)
These are to the break point on the saddle which can be the centre or near the front edge or rear.
If you measurements are accurate(and unfortunately 0.5mm is significant) then you would comefrom centre of 12th fret- 320 plus 2mm from the bridge edge to full scale length plus 2.2mm to compensated length minus 1.2mm (half saddle thickness) so the front of your slot would be 3mm from the edge.

So you inotator measurements are going to be pretty close to what you would calculate.
Maybe move the slot back 0.5mm so the break point is towards the front of the saddle

[gratay]

Grant,

The issue when I was compensating my 12 string was string height at the nut being too high.

I did my last 6 string using the compensator jig and it worked out ok.

i remember following the trials and tribulations of your 12 string set-up issues which is why I have completed all the nut work/ string height prior to setting the intonation.

[gratay]

Hi Grant,
For this scale length you would be looking at added compensation of 1.7 to 2.7mm on the high e and 5-6mm on the low E. (based on the Stewmac fret calculator)
These are to the break point on the saddle which can be the centre or near the front edge or rear.
If you measurements are accurate(and unfortunately 0.5mm is significant) then you would comefrom centre of 12th fret- 320 plus 2mm from the bridge edge to full scale length plus 2.2mm to compensated length minus 1.2mm (half saddle thickness) so the front of your slot would be 3mm from the edge.

So you inotator measurements are going to be pretty close to what you would calculate.
Maybe move the slot back 0.5mm so the break point is towards the front of the saddle

thanks jeff,....exactly what your saying is the conclusion I have come to as well..
One more thing I am going to do is check the intonation of all notes along the scale length of the E strings ..It should tell me the accuracy of the intonator jig which by the measurements you've posted appears to be spot on..
I will then slowly move the saddle location back w/ the intonator until I can get the break angle as far to the back of the slot as possible without the B string being to far off..

I guess my major concern is the front of the bridge splitting due to the slot being so close to the front??

cheers Grant

[Beau Hannam Guitars]

The ibex fret ruler is indexed off the position of the high E, NOT the middle of the saddle. It says that on the ruler.

[johnparchem]

When I looked at the picture with the Ibex ruler if the dark arrow was the correct mark for your scale length the bridge would be located such that the leading edge of the saddle on the #1 string would be on that mark. If set that way the bridge would be closer to the nut and you would be just perfect for your intonator. Of course I get if it was the mark on the other side, something is off.