Official Luthiers Forum!

Okay, I am getting ready for my first acoustic build and have been doing a little reading online. Can someone give me an explanation on how growth rings effect the top/tone. I am assuming the more GRPI the stiffer the top will be. Also what is grain run out and what does it cause or why stay away from it.
Thanks
Travis

Runout can cause your top and or braces to shatter. When the tree grows, the stongest fibers normally run straight up the trunk from the bottom to the top. If you keep those in tact, you have the strongest wood. However, sometimes a tree grows with these fibers spiralling up the truck. If you cut the wood parellel to the center of the trunk, you will cut across those fibers. This is called runout, because these fibers run out to the surface of the cut wood, rather than parellel to it. In selecting billets to resaw for tops, a good preparer will split the billets along the length with a wedge. Splitting will follow the long fibers, and reveal how to orient the wood to resaw and not cut the long fibers. If you do not do that, the wood will be weaker. In the extreme, you can see the effect of runout be flexing a thin pieces of wood that is cut accross the grain. It will break very easily. Runout will not be that extreme but you get the idea from this.

So we buy our top wood from good suppliers that prepare with minimum runout. You can check by removing some of the top wood in an excess area and splitting it with a chisel. You have to attempt to make this split parellel to top surface, not between growth rings. This will reveal how close to parellel the sawed wood is to the long fibers. It very rerely can be perfect throughout the entire top.

For braces, we get billets and split them with a chisel to reveal the orientation of the long fibers, then we work with the wood to preserve that orientation.

Rings are another story. The more rings do not necessarily make the wood better. Others will give opinions on that who have more experience than I do.

Growth rings per inch is not a reliable indicator of stiffness or any tonal qualities. Many builders use tighter grain for aesthetics, and also may lean toward tighter grain to cater to market expectations. These beliefs and expectations of much of the buying public are misguided however, often based on rumor or selective observations.

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Eschew obfuscation, espouse elucidation.

Dave is right on the money!
I've made guitars for over 30 years and repaired many famous makers guitars also over this period.
Grain width is NOT a factor of the musical quality of a top!
Preparation of the cutter is !

Is it from a split billet?
Was there any twist of the trunk?
Is it stored correctly!-allowed to dry out !

Buy from the OLF sellers of tops & you'll be fine -they sell good cut woods!
As wbergman says!

Mike

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Mike Collins

"Runout can cause your top and or braces to shatter"

With all respect I've never seen this happen,
and after 40 years of being involved with guitars I will say it won't unless there is a vigorous assist from a knee, derrierre, doorknob or baggage trolley.
I agree that perfectly quartered wood with zero runout is the most desireable and in regard to the wood that I'm interested in, aged European Spruce, you can forget about it, at least on this planet.
So, what we are left with is to select what will serve our purposes from what is available which then becomes an excercise in flexing, handling (testing and smelling if that works for you) and evaluating the actual pieces that are available, all of which will exhibt some deficiency or other according to the experts.
Forget the fact that some of the best guitars I've seen and heard (steel strings especially) and even built,were made from the "worst" wood.

www.guitarsbydavidlaplante