Locating the bridge

[Geocoucou79]

Hi everyone,

Neck is now bolted on the body and fretboard extension glued to the soundboard. I gave an extra layer of tru-oil and I must now locate the bridge position.

After reading about it and watching youtube videos, I'm more confused than confident. I thought about making a bridge location jig like some great ones I saw online but it felt complicated so I'm trying to follow the procedure from Cumpiano.

First, my bridge is already slotted and my scale is 25.4 inches.

Cumpiano says the distance between the nut and the center of the the bridge slot should be 25.55 inches which is 0.15 inches more than the scale at the center point for compensation (which he does not say). Does that make sense? The book doesn't tell what the slot angle is but I did the math and it's about 2.2 degres.

A Youtube video showed this that I thought was relevant. But the math does not work, it has to be X 0.0097 and x 0.0047 rather than 0.097 and 0.047. With these I would get the center point of my saddle slot 0.185 longer than the scale.

Sorry about all the numbers but could anyone enlighten me please?

Bridge locating.jpg (24.12 KiB) Viewed 1551 times

[Carl Dickinson]

I use this tool on Mattola's website, https://www.liutaiomottola.com/formulae ... sation.htm. This and a good rule with 1/10ths of an inch get me there just fine.

[Herman]

Or a similar one from Stewmac. Simple and always correct.
https://www.stewmac.com/fret-calculator/

[Geocoucou79]

Thank you guys, I was not aware of these tools. I don't get the same calculations with both tools though. But not by a lot.

Stewmac
Treble "E": 0.089"
Bass "E": 0.214"

Liutaiomottola
Treble "E": 0.091"
Bass "E": 0.1976"

I guess I could call 0.09 and 0.2.

I ended up making a simple jig to register the distance from the nut to the 12th fret and when I switch it around I get the theoretical scale.

[peter havriluk]

I've had excellent results using a (horrors!) StewMac Saddlematic tool. Once it's adjusted for the saddle thickness, it takes very little time to positively locate a bridge, and I've had a real live luthier double-check the Saddlematic's location against his own location calculated independently and the tool matched his calculations. Trouble is, StewMac doesn't sell new ones anymore.