More relief on bass side than treble - Collings OM1?

[ProfChris]

Hand builders will usually achieve this when levelling the frets. After they are level, the middle frets are sanded a little more along the bass side. I don't think the tiny difference in fret height can be felt by the player.

Factory production might be able to mill the extra relief into the board, and then mill the frets to match using clever machinery. I can't recall if highly skilled hand builders do this too - it would need some skill, but I can envisage how it might be done (levelling with a short sanding beam, following the board rather than trying to level the full length).

As an amateur builder, just getting the frets reasonably level is hard enough without trying to be extra clever!

[gmel555]

Originally Posted by ProfChris

Hand builders will usually achieve this when levelling the frets. After they are level, the middle frets are sanded a little more along the bass side. I don't think the tiny difference in fret height can be felt by the player.

Isn't this an adjustment of action, not neck relief?

[Dotson]

Originally Posted by ewalling

It's something I've noticed on many of my guitars: when sighting down the neck, it can look pretty much completely straight on the treble side but slightly curved on the bass side.

I have a Martin Custom OM that has the opposite pattern: it has more relief on the treble side than on the bass side. I believed this to be due to a twisted neck. But reading this thread, it is interesting that there does not seem to be a clear understanding or clear guidance on the relief on the bass side vs. treble side - for any kind of guitar, e.g. bass or 6 string. I guess I will experiment / play around with the truss rod evaluating the relief and buzzing one string at a time.

[lowrider]

How much difference are we talking about here?