I just got some sinker redwood for my next soundboard and it's almost 6mm thick (1/4") how much do i have to plane it down?
Damn that's thick. Just measured my Seagull S6's top and it's 2.5-3mm thick. It depends on the wood of course, but 6mm is Far too thick. You could make 2 soundboards out of that!
1994 Seagull SM6
2007 Takamine G5013SVFT

2008 Epiphone Les Paul Standard Plain Top (Cherryburst)
1964 Gibson Melody Maker D (DC)

Traynor YGL-1

MXR Distortion III (C4 Modded)
we don't have a bandsaw, either. we used a high quality scraper to thin the top on this guitar, but we got a mill and will be using one of these
for the initial thinning for the next one.

btw, lmi does top thickness sanding, and they do all tops but red cedar and redwood at 2.8mm thick. redwood they do at 2.9mm.
Quote by Skeet UK
I just looked in my Oxford English Dictionary and under "Acoustic Guitar", there was your Avatar and an email address!