How To Check My Mahogany Slab For Guitar-worthiness?

[strawtarget]

So some time around 1995, I had this idea that I wanted to build a guitar. My stepdad took me to a local lumber place and we got a 2" thick slab of flat-sawn (plain-sawn?) mahogany, allegedly Honduran mahogany.

High-res picture with flash

High-res picture without flash

It got put in a closet where it sat for probably 8 years, and moved into a humid Houston garage probably 2 years ago. I saw it in there while visiting the folks, remembered the abandoned project, and now I finally want to turn it into a guitar. I took it back home with me to Austin about a month ago.

We bought it in kind of an odd condition. One end is painted over in white paint or primer, sealing the grain on that side. I believe the whole piece has been stained some reddish-orange color. Concern #1: How deeply might have this stain have penetrated? I hope to get down to bare wood.

It is flat-sawn and there are some nice grain patterns that I want to try to show off under a translucent finish. I think I'll be able to cut out the body so that the arcs in the grain run down the guitar's centerline. Concern #2: Just about every mahogany guitar I've ever seen was made of quarter-sawn pieces. Is there a fundamental problem with using a 1-piece flat-sawn body?

The wood is slightly warped/cupped. It was stored without care... certainly not "stickered and stacked". It's not TOO bad, though. It is my belief that I will be able to take it somewhere and have it planed and sanded flat and still have 1-3/4" thick material. I hope so anyway, since I want a 1-3/4" thick guitar body! Concern #3: After 10+ years of sitting around, should I consider the piece "stabilized", or should I take it somewhere and have it kiln-dried or something?

I've looked for checks/cracks on along the edge and found none, but one edge is painted and the other is very rough which makes it hard to tell for sure.

Is there anything else I should look for when examining this piece of wood? I need to sweat the small stuff and obsess over as many tiny details as possible here! Seriously!!!

[Setch]

Chances are it's pretty dry now, and if it's been in the same place for a few months, pretty well equilibrated. I'd go ahead and get it thicknessed, or run a plane over it. With a smooth surface it's much easier to find any checks or splits which might be lurking.

Odds are it's a keeper, but you'll have a better idea once you've got the saw marks away and maybe trimmed the ends off.

[Rick500]

I can't answer all your questions (I'm fairly new at this myself), but I can tell you that I'm building a solid mahogany guitar right now, and my mahogany slab looked just about identical to yours before I started working it.

I don't think your mahogany is stained. Maybe it had some sort of sealer or wax or something applied to it. Does it feel waxy?

I planed a bit off of each face of mine and the coloration is now the same on both faces.

You shouldn't have a problem building a body out of that piece, regardless of how it was cut.

Mahogany is relatively dimensionally stable, so you probably don't have too much to worry about.

One word of caution: If you're routing the endgrain for any reason, be very, very careful and only take off tiny amounts of wood at a time. I had a huge tear-out problem on mine. I ended up having to cut a quarter inch off and reshape the bottom of the body. Next time I work with mahogany, I'll rough cut it on the band saw and then Robo-sand it.

Edited December 18, 2006 by Rick500

[prs man]

looks good to me and I have been working with wood for over 20 years.

over time your mahogany has got dark and as you cut and plane to thickness you will see it lighten in color.

Rick500 is correct when saying the end grain will tear out so take small amout off at a time and then sand to your line

[unclej]

equilibrated? i'm gonna have to check that out but if it's not a real word it should be.

ok, i checked and it's a real word. that's why i love this forum...learn something new every day.

[strawtarget]

Cool.... nice to hear that I've probably got a "keeper" here. And very interesting to learn that the wood itself has gotten this dark and it's not stain. Weird!

I think if I rip the board to something closer to the desired body width (leaving an extra 1.5 inches on each side) before planing/sanding, I'll have a better chance of getting the full 1.75" thickness I'm looking (for since the overall amount of warp will be reduced). Any reason I shouldn't do that?

[Rick500]

If that's still not enough, you might be able to rip it in half and individually plane the halves, then glue up the pieces.

[guitar2005]

I think if I rip the board to something closer to the desired body width (leaving an extra 1.5 inches on each side) before planing/sanding, I'll have a better chance of getting the full 1.75" thickness I'm looking (for since the overall amount of warp will be reduced). Any reason I shouldn't do that?

Plane the wood down until 90% of the rough saw marks are gone. Then, let the wood sit for a couple of days and check if it warped. Flatten one side and plane until no saw marks are visible. Wait another 2-3 days and plane to final thickness.

The wood will move a little but keep in mind that the top doesn't have to be perfectly flat unless you're gluing a top on the guitar, which you are not doing.

Honduran Mahogany is one of the most stable woods out there. I would not worry about warpage too much.

[Drak]

Take something very straight and flat and lay it across the width of the slab, then measure in the center from the bottom of your flat piece to the wood, then double that figure, that's how much you'll lose to flatten it out.

[fryovanni]

8 Years air drying. It is done drying. It will fluctuate very little from here on out(VERY LITTLE). If you can take it to a shop that has fair size equipment let the know what you need and that you need to keep 1.5" if at all possible. They will do their best. If you come up a little shy. Consider a nice top or back to make up the difference(might look nice anyway).

Peace,Rich

[Mattia]

It's dry by now; mahogany is one of the most stable woods you'll ever run across, so don't hesitate to use this. Pretty much all guitar bodies are made using flatsawn wood (simply because the quartered stuff is hard to find in those widths, and getting harder every day), so no worries there. You may think they were quartersawn bodies, but I very much doubt it. I've got a few African mahogany bodied guitars I've made that has quasi-quartered bodies, but really, it doesn't matter.

It's not been stained, that's what aged, air-dried mahogany will tend to look like. It'll lighten up a lot once you plane it/get it thicknessed. Plane it, then examine for cracks.

[westhemann]

The wood will move a little but keep in mind that the top doesn't have to be perfectly flat unless you're gluing a top on the guitar, which you are not doing.

if the top aint flat it's gonna be damn hard to put a level finish on it.

you casn do as you said and,if you know the shape you are using,trim it down to size before planing.