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How important is it for the top and back to be quartered? The opposite is, what do you think about using flatsawn plates for top and back?

Tops, yes .. backs and sides, nice, but not so much a definite requirement ... for instance, any quilted figure wood is flatsawn, so is birdseye maple .... plenty of nice wood is rift sawn, or changes on the board from rift to flat, or rift to flat to rift again (backs especially)

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Tony Karol
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For the back and sides, preferable but not mandatory, and lots of fancy looking guitars have flatsawn backs. As for the top, it's quarter sawn all the way home!

I think it is critical for a top to be quartered, especially if using a softwood top. A flat-sawn soft wood top would not hold up, at least not at standard thicknesses. The back and sides are less critical and depending on the species it will work fine. Certain woods will still bend relatively easily if they are off quarter (walnut, cherry for example). Other woods, especially with figure will break more easily when flatsawn. If I am using a set of back/sides that are off quarter I am always paying close attention to the bracing and side reinforcement I'm using. Often I will strengthen the bracing a bit to compensate for the weaker plates/sides.

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Josh House

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Flat-sawn softwoods are actually slightly stiffer along the grain than quartersawn, but there is the issue of lower stability and lower resistance to cracking.
In fact, the cut that is least likely to crack is when the grain is in-between.....roughly 45 degrees to the face. But tops with that grain orientation are the least stiff across the grain.

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John

I learned from the very beginning that quarter sawn is the best so that's all I use. I have at one point considered and indeed have used flat sawn for necks and in most cases even then I will laminated it so that it is as close to quarter as possible. I don't know if that is just old school thought since it seems there are a lot of guitars out there and lots of back and side sets being sold flat sawn. Since I bend on a hot pipe I'd worry about a flat sawn piece splitting.

My opinions are pretty much in line with everyone else's. I will say though that I'm not particularly scared of using, say, a nice red spruce top that has well quartered grain in the center but starts going riff close to the edge of the lower bout.

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Aaron Craig

What they all said. Stability is an issue to be considered. On something as small as a guitar, wood movement is not extreme but it's still a very real phenomenon. To over-simplify what happens, think of it this way: Assuming we have well-dried wood that is now only reacting to ambient moisture, flat sawn wood tends to get wider and narrower as it moves with humidity. Quarter sawn wood tends to get thicker and thinner. You could measure changes across the width of a quarter sawn piece if you had precise measuring tools, but you probably wouldn't notice it. All that said, even with perfectly quarter sawn stuff, if you glue it up cross grain (say, with a brace) in high humidity and then bring it into a very dry house in the dead of winter, you'll probably see some cracks forming. I think the risk with flat sawn material in the same scenario would be higher.

The curious thing to me is that we are very careful about quartered tops and braces but dont alway apply the same logic to backs if its pretty. It seems to me that flatsawn backs are a risk of some degree or other.

As it becomes harder to get quarter sawed wood, we give way to flatsawn stuff. Martin made some pretty boring quartersawed BRW guitars when they could get it. They were mostly interested in stability and sound rather than crazy grain. Hopefully we won't have to give up quartered wood for soundboards.

Does the back work as hard as the top? By that I mean is there that much tension on a back?


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I think for the braces, run out is even more important that quarter. Some people use flat sawn braces.

I think for backs and sides, there are other factors that are important to reduce the chances of cracking. Ramirez, about the most famous and well regarded classical manufacturer, is infamous for guitars cracking, tops and backs, at least in the USA. I am assuming that Ramirez built in high humidity in Spain, resulting in guitars that are less forgiving to improper winter humidity control in the USA.

Some builders heat treat the backs before building, such as by pressing between hot plates. This supposedly changes the fibers, etc. Do not do this if there is any wax anywhere on the wood.

Surely any heating of the back is purely and simply to facilitate the usage of hide glue for attaching the braces, rather than altering the composition of the wood.

Some builders do indeed bake their tops in an oven to dry them out fully, reportedly with good results.

The back heating I am talking about is of the raw wood before it is joined. It is heated up just as hot as for bending sides, and restrained flat to prevent warping in the process. It then is allowed to equilibrate to the atmosphere prior to joining it.

One method is to lay the wood on a flat surface, put heating blankets over it, and then a weighted board over that. With a thermometer, heat to the same range of temperature that you do for side bending (~300F???), then let sit to cool for a few hours or overnight. This supposedly releases tension built up in the wood. I straightened a severely warped ebony fingerboard blank clamped between steel plates and cooked in the oven. This was a rough cut blank of uneven thickness. The high spots squashed down like putty and did not rebound. I left the blank out unsupported for several months after this and it never warped in the slightest.

Some people use a more engineered press. The type of press used for laminated some items might work. I think the ones I saw were made for mounting photo prints to boards, but I am not sure.