String Compensation Test Rig

[kiwigeo]

After struggling to get a spreadsheet to produce sensible nut compensation values I opted to build a jig to work out nut and saddle compensation. The jig allows for adjustment of scale length, action, tuner to nut distance and saddle and nut compensation. For each scale length a dummy fretboard is loaded into the jig. Since one of my current builds is a multi-scale a dummy fretboard is made up for each string. The signal from an under saddle pezio pickup is fed through a pre-amp and then into a laptop running Strobosoft and AP Tuner.

Bridge end of the jig with saddle and pickup. Bridge is adjustable for scale length and action.

Nut end showing nut adjustment. Bone nuts are changed out for different string guages and string height at nut. The headstock can be changed out for different tuner to nut run lengths.

Jig outputs to a pre-amp and then to a laptop running Strobosoft and AP Tuner.

[jeffhigh]

Looking good, I like how you have taken all the practical factors into account.
How are you fretting the string, do you have a standardised force?
How are you measuring the small nut and saddle compensation values?
cheers

[kiwigeo]

Looking good, I like how you have taken all the practical factors into account.
How are you fretting the string, do you have a standardised force?
How are you measuring the small nut and saddle compensation values?
cheers

Thanks Jeff,

The only factor I'm not allowing for is relief but it wouldn't be hard to set up the jig for same.
The string is fretted midway between the frets with my finger.
Measurements are made with vernier calipers......there are a number of points on the jig where measurements of changes in nut and saddle position can be made.

The jig will never be as accurate as the mathematical modeling approach but for me it's a matter of micrometering the brick. I hand cut my fret slots so the added accuracy of the former method would be negated by the errors in fret position.

[johnparchem]

That is a nice test rig. Would you just use a different saddle if you wanted to compensate for a different action height?

[kiwigeo]

That is a nice test rig. Would you just use a different saddle if you wanted to compensate for a different action height?

John, the two screws either side of the saddle are used to adjust saddle height (=action at 12th fret).

[auscab]

Thanks for showing that Martin . I love seeing that sort of older school way of testing , if that's what it is now ?
Rob

[kiwigeo]

Thanks for showing that Martin . I love seeing that sort of older school way of testing , if that's what it is now ?
Rob

Rob, the jig is a work in progress. Its already undergone a few modifications to make it easier to use.