Tune-o-matic Brain Fart?

[jer7440]

I am having a total tune-o-matic brain fart. Which side should be set to the scale length...treble or bass? It seems like I remember the treble is at the exact scale length and the bass side slants back making it a little longer. Can someone confirm this for me?

Thanks

Jeremy

[westhemann]

treble,duh...hehe

[jer7440]

Thanks Wes...that's what I thought, and then I started second guessing myself.

[MCH]

I find what works best for me is string up the guitar with bridge in relatively correct position. Then tune it up and adjust the bridge (all saddles lined up in the centre) until you get the closest correct intonation. Then mark that position and do the permanent fixing. I like doing this so I can also see how the strings are lining up with the fretboard.

On my first guitar I went by the manufactures recommended placement measurements and ended up a bit too far back. I can still intonate but all the saddles are basically in the forward position. Every time I look at it, it irks me. Someday I'll revist this and relocate the bridge.

[Briscriggs]

treble side. But I have one question for you. If you install the bridge when not under tension ,the scale lenghth will probably change won't it. Also a slight backbow is recomened won't that also change the scale lenghth.

[GregP]

No backbow is ever recommended. Quite the opposite. If you have backbow, you're in a world of hurt.

The bowing and general tension don't change the scale length. The scale length is the scale length, and the frets are in place according to some pretty specific math. No amount of change to the strings will change this, and any changes to the curve of the neck should be fixed-- but even if not fixed, the "arc" of travel would be such that scale length isn't really impacted in any practical way. In pure theory, you're correct.. but the change is so infantessimal that for practical purposes it's not worth calculating.

You will never need the bridge to be closer to the nut than than scale length for any string. Compensation is to compensate for strings getting pulled sharp as they're fretted. The compensation is for the saddle to therefore have a slightly "longer" length than pure linear mathematics would tell you.. the longer length produces a slightly flatter note from the fret to the bridge, which compensates for the string having been pulled sharp.

As it happens, the low E string is the most likely to get pulled sharp by more cents... so by angling the TOM back a little bit, you're giving yourself enough wiggle room. It's unlikely that a low E string will EVER need to be at the exact scale length, so it's very safe to start with the bridge angled back a bit. But it IS possible that the high E will be able to be fretted with only a wee touch of compensation necessary.

Greg