tree rot analyzer

[Chris Smith]

Thats how I pick watermelons. Tap them and if they sound like my dogs belly, they are ripe!

[philba]

yummm, that's an image I want when slicing open a watermellon...

[Chris Smith]

It works 100% of the time, and pisses off a lot of people I know, who still guess after more than 50 years, and still get the over or under ripe mellon. I call it G-flat. [G for Gastro]

[jimandy]

I'm rethinking the drilling idea and find it would be impossible for one reason. The WIFE! She'll never let me loose with a drill on trees in our yard. So it's back to tomography, or something in between the Picus and a hammer-stethoscope. Seems like a practical compromise would be an electro-mechanical thumper driven by a repetitive pulse generator which would provide a reference signal to trigger the sweep on a scope while applying the output of an amplified sensor that "listens" on the other side of the tree. I would have to take into account the tree's diameter so might need to adjust the thumping intensity and sensor amplification accordingly.<p>I welcome ideas on the thumper / sensor design. I'm better at circuitry than at fabricating widgets so would prefer using core parts that are off the shelf. I'm not averse to routing out a bit of bark down to the cambrium for contact with the transducers. Can then patch that up with some of that glop for healing tree scars. Send ideas and I'll report results with screen shots of traces, etc. I'll probably have to haul in a few logs to the basement shop to do the development.<p>Of course this might show me up for the "sap" I am.<p>[ June 19, 2005: Message edited by: jimandy ]</p>

[philba]

well, good luck, you'll need to do some sort of resonance signature analysis. Pretty sophisticated stuff. I'd build an interface for a laptop and do all the number crunching on it. <p>One other possibility is to measure the speed of sound (or attenuation thereof) in the tree trunk. It seems to me that rotten wood will pass sound differently than healthy wood. I'm not at all sure how you'd calibrate this thing, though.<p>By the way, the drill idea is pretty harmless to the trees, especially if you plug the hole with a peg dipped in bleach or similar. A couple 1/4 inch holes are basically nothing to a tree. Consider how Maple syrup is gathered (1" hole) and they live for years like that.<p>Phil

[jimandy]

Philba: <blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr> I'm not at all sure how you'd calibrate this thing, though. <hr></blockquote>
I'm trusting to the old empirical method. The Black Oaks that we worry about are all 30 to 50 footers. The ones that have fallen in the past all had cores decayed over 80% to 90% of the diameter at the base ( a few feet above ground level). I figger if I can find enough sample logs and do a snapshot of the different scope traces I'll see some differentiation. I'm just trying to narrow it down to the trees most susceptible to falling. If I really do it right, I'll hike out in the woods with a UPS driven scope and run some tests of trees with a follow up using the drill method.<p>And if all this works out, I'll sell my system as a watermelon ripeness, or dog's belly gassyness, tester.

[peter-f]

philba- the maples better NOT have 1" holes... 1/2" will suffice.. and grow over within a year.<p>jmandy- that kind of rot is evident (usually) via lesions... and very different sound from a healthy tree-- but you need to knock real hard to hear the difference between a resonant healthy tree or the echo or deadness of an unsound one. Try a stethescope.<p>Also - lots of holes may confuse the issue with woodpeckers, and (in many areas) long-horn beetles... the aviary guys are cutting the beetle-infested trees down Wholesale!<p>[ June 25, 2005: Message edited by: peter-f ]</p>