So some may ask what is the value of this process prior to building. My current project provides an example. The previous post shows the example of measuring a great tap sounding port orford plate. It was very stiff and my hands on lead me to believe it would make a good top for a nylon string guitar I am making.
Referring to the image below one can see that the top target of 2.03mm is relatively thin for a classical. This thickness calculation normalizes each plate tested mostly for stiffness but also takes the mass of the plate into consideration. But the density, 464 kg/m^3, will result in a top that is about 20 grams heavier than I normally use in my nylon string instruments. Maybe ok for a steel string, but I go through a bunch of effort to remove a few grams from my classical bridges, maybe this wood is not the best choice.
- port orford top thickness.JPG (60.08 KiB) Viewed 6243 times
So I went through my stack and pull out a WRC cedar top I have had for 6 years or so. Very tight grain lines across the entire plate and perfectly quartered. It also had a wonderful tape tone that rang clearly over 5 seconds. The tuning app used it in the testing heard the ring for over seven seconds. So I measured all of it attributes as shown in my video.
- wrc thickness 1024.JPG (74.37 KiB) Viewed 6243 times
As one could see that this plate was not near as stiff and resulted in a thicker top, but with this woods significantly lower density of 331 kg/m^3 even with the thicker top it will weigh more than 20 grams less.
While the method uses the plates tap tones in combination with it physical measurements, I have seen alternatives where the plates while thicknessed are normalized for mass or using deflection test normalized for stiffness. I like the method I got from the Gore method as I am able to make determinations early in the process. If the two alternative methods were used with the Port Orford, in the case of normalizing for mass I would have ended up with a very thin and floppy plate; normalizing for stiffness I would have ended up with a heavy plate. Working with wood one knows these different methods would be OK as in a given species of wood there is a good correlation between density and stiffness.
I never used Port Orford before so it was hard to know how to compare it to wood I have experience with. From simple measurements I would know that it was very dense. I could also feel that it was very stiff, but was the measured stiffness enough to make up for the above normal density. With the work of making sure the plate was flat and rectangular I was able to make that determination very early.
