Good question Scott: I have not tried to find that out. Normally I mark the
entry hole, cut about 4 cm above that and the carefully router down to the
exact area. My hunch is that the readings would not be significantly
different, except perhaps in areas where the cutting had released checks and
longitudinal forces. Then you might see different widths in cracks. I had
one hemlock I drilled in situ and found a crack. Once I got around to
dissecting it the specimen had dried out and the crack was larger than the
original.
I did try readings in frozen wood vs the same wood unfrozen and did not see
marked differences.
Julian Dunster
----- Original Message -----
From: <dscottcul@xxxx.net>
To: <uktc@xxxxxxxxx.co.uk>
Sent: Saturday, December 15, 2001 2:27 AM
Subject: Re: Resistograph
I don't know... $60US might be really cheap if it saves
the analyst even an hour of time, just once in
interpreting their results and understanding how to make
better use of the diagnostic tool.
Your observations sound very much like Shigo's relating
to the Shigometer when practitioners started looking for
"normal" or broadly applicable readings. Gotta
establish your own local, if not specimen baseline.
One technical question... does anything happen to the
characteristics of the wood or the individual rings at
any one cross sectional slice when you cut through the
log to make a cross section? If you drilled a long
section or standing trunk at point A, then cut a cross
section nearby Point A so you you visually observe the
pattern of rings, decay, discoloration... and then
drilled nearby in the same orientation through similar
looking wood, would there be any significant difference
in the readings? Does the cutting release any forces
like tensions or pre-strains that were "locked" in the
wood?
--
Scott Cullen
There is not really a "normal" reading for any one species. Typical may
be a
better concept. Having written the interpretation manual for IML, and
having
just finished work on their new video, I am still aware that many folks
believe the Resistograph will give "the answer." In fact each tree is
different, even among a stand of the same species. What you can
typically
expect to see is that conifers will show fairly clear ring
differentiation
as long as the rings are well spaced. Some hardwoods will also show
clear
rings but in general, they are less easily detected in the chart. This
is a
simple reflection of wood structure. I recommend all Resistograph users
to
build up their own data bank of species and readings. It helps if you
can
later dissect the tree and see how well your interpretation actually
matches
reality. Even if you practice on firewood bolts, it helps to develop a
better sense of what to expect and how much to read into the charts. I
spent
many hours drilling various logs and then cutting and polishing the
cross
section at the point of drilling, to develop and reasonably good sense
of
what the readings mean. You should also know that the later models are
much
more sensitive than the early models.
I am not sure how IML is distributing the interpretation manual in
Europe.
In North America I believe it can be purchased directly from IML USA.
Alternatively, I can send you a copy - $US 60.00 which is expensive, but
reflects the costs of copying and developing the manual.
Julian Dunster
Bowen Island
BC
Canada
----- Original Message -----
From: "treecare" <treecare@xxxxxxxx.com>
To: <uktc@xxxxxxxxx.co.uk>
Sent: Friday, December 14, 2001 5:06 AM
Subject: Re: Resistograph
Dose any one know if there is any published data for Resitograph
readings
i.e. what a 'noramal' reading for a particular species should look
like,
etc.
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