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History of the Forest Products Laboratory

Interview #920: McDonald, Kent A. (June, 2009)

View all of First Interview Session (April 10, 2008)

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00:16:00 - 00:20:51 Ultrasonic Testing

Ultrasonic Testing

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That's one of the areas where---and we had an ex-Navy man here that was in electronics. And I was telling him about how we might locate defects in logs. And his experience was in sonar, with the Navy. I was looking at it because in logs, sometimes the grain spirals. When the grain spirals, then when the wood dries out it [tends] to un-spiral. A good example of that is if they put a telephone pole in the ground and put cross-arms on it, when it dries out then the cross-arms change direction. So, that was one of the things that we were going to try to find in the log, was if it had spiral grain. And I was thinking of the idea that you'd just hit the log on one end at twelve o'clock, for example, could you put a receiver on the other end and listen to where it would come out strongest. And he said sure, he said you should be able to do that. And he said that at the same time if you hit it on one end, you'll get a reflection back from where all the defects are in that log. So well, that's fantastic. If that's the case, we can tell where the defects are as well, so we have an internal picture of the log.

Well, that kind of simple explanation from the Navy guy launched [a] whole [research] program and we started with ultrasonics. And with the idea of eventually getting to logs, but we thought lets learn what we can with ultrasonics and lumber first. And in the spin-off from that was a system where we could locate defects in lumber. And then the spin-off from that was if [we] can locate defects in lumber then what can you do with that information? And, so we had spin-off programs on, and people writing computer programs, which were very advanced for that time. [With] the information from a board, [we] could really make the decisions on how to rip it and cross-cut it. So we had programs that stimulated [other research] programs in a lot of universities [and industry] around the country as well as other Forest Service stations. And, [many] then wanted a piece of the action, and [many] had an idea of how to apply it. So, it fosters a lot of other research because of the possibilities, and the possibilities at that time were fantastic.

Our bottom line was to try to get better utilization of the forests that we were growing, rather than getting just fifty percent of the tree converted into a product, and the rest going to, what at that time was called waste. Some of it was burned. Some of it, very little of it was chipped. Nowadays, a lot of things are done with the extra byproducts. But, at that time they weren't. So we were looking---and the highest value would be in converting it to solid lumber, at that point, and veneer. We had some veneer studies as well. But, solid lumber was the most important thing. And our idea was if [we] could cut one tree down instead of two to get the same amount of product, it seemed a lot smarter.

But, to sum up that approach, since then the whole Forest Service has changed [direction]. With the objection of people that think that [we were] cutting all of the forests down, their solution was to just stop cutting all together. And, so, a lot of our product was supplied from outside of the country and imported. So, and that's a big generalization as well, so that's not an explanation of everything that's involved [here].

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