Mahogany guitar top thickness

[Rob Mercure]

Folks, The first "real" acoustic guitar that I owned was a Guild D-25 that was, other than the bridge and fret board, all mahogany (Swietenia sp.). It was stolen in 1980 and I replaced with the coincidentally numbered Martin D-25K guitar that I truly love and have played since then. But the Guild was really great with a tapering neck that at the first few frets was thinner than my 1960 Strat. So since I've decided to make a top for the Washburn cheapo that I pulled the neck off for practice I decided to use some CA mahogany boards that I've got rather than buy a spruce top. But it's been 29 years since I last saw my guild (hey, if you ever see one - one of the flat back ones - with a walnut truss rod cover replacing the plastic one contact me - my name used to be inside) and I can't really remember the top thickness. To start off would the top thickness be similar to spruce, thicker or thinner? Just to give me some guidelines before I then hand tune it. Thanks

Rob

[FRANK]

TRY .070

[Rob Mercure]

Thanks - If I tried 007 he'd probably shoot me

Rob

[Tim Mace]

.070 sounds thin, get more opinions........but I prefer thicker.Maybe 3mm. Do you have enough for 2 tops?JIC

[Rob Mercure]

Tim, yeah, I'd decided that 0.07 was a bit thin as I found a partial mahogany top (from a guitar smashed in the '70s by a jealous friend mad at his GF - never understood folks who take their anger out at smashing and hitting anything) and the top on that one was 0.09. And the three layer top that came off the guitar was about 0.12 so I think I've decided to shoot for around 0.09 - 0.1 to start with. I probably do have enough for two, maybe three, tops depending on how well I want to make the pieces match and how many pieces the top is. I've got one two piece, one three piece and I could do a four piece having a bookmatched center with 1.5" pieces added at each side of the lower bought. The color on this wood matches up really nicely but the grain is all over the place from quarter sawn for the two piece to quarter/plain mix for the four piece. So we'll see.

Thanks,

Rob

[Bob Webster]

Rob, even 0.10" might be on the thin side. Mahogany isn't quite as strong as spruce and most spruce tops on steel string acoustics end up around 3mm or ~0.125. If it's a smaller bodied guitar, you might be able to go a bit thinner. The one reason that you might be able to is because the across/with the grain stiffness ratio of mahogany tends to be a bit better than for spruce. As for choice of pieces, the quartersawn 2-piece set would get my vote.

Cheers,
Bob

[Rob Mercure]

Thanks Bob, I'll keep this in mind once I get to resawing the pieces. And the quartersawn pieces are the ones that I intended to use as the others were mentioned as a speculative response to a question. Since I've only got one body to make the top for the 2 piece was where I intended to go orginally - I think that Tim was probably asking if I had sufficient wood to have a second chance if I screw up the first effort - and I guess so if I wanted to go with the plain sawn multi-piece top. The 2-piece will just barely fit with about 1/4" to trim off each side. As my resawing set up is primative I'm allowing more kerf wastage than someone with a large bandsaw would need - with realy good control I suspect that someone could get 4 pieces out of this plank but I'm going to be happy with two.

Thanks

Rob