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Trimming and Planing Rough-Cut Wood For Efficient Dendrochronological Sample Preparation and Storage

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Wood samples larger than increment cores collected for tree-ring studies are often obtained using chainsaws and, less frequently, 2-person crosscut saws. Saw marks on cross-sectional wood samples can be quite deep and uneven, and sanding rough-cut wood cross-sections is inefficient in terms of processing time and wear on sanding belts. Trimming rough-cut wood samples with a band saw or treating with a surface planer creates a smoother initial surface for sample sanding and polishing. Sample trimming with a band saw or surface planer is also useful for post-analysis archiving and wood storage, when excess wood can be removed and smaller samples entered into storage. Band saw and surface planer safety techniques are also discussed.
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TECHNICAL REPORT
TRIMMING AND PLANING ROUGH-CUT WOOD FOR EFFICIENT
DENDROCHRONOLOGICAL SAMPLE PREPARATION AND STORAGE
J. JESSE MINOR
1,2
* and ALEXIS H. ARIZPE
2
1
School of Geography and Development, University of Arizona, P.O. Box 210076, Tucson, AZ, 85721-0076, USA
2
Laboratory of Tree-Ring Research, University of Arizona, 1215 E. Lowell Street, Box 210045, Tucson, AZ, 85721, USA
ABSTRACT
Wood samples larger than increment cores collected for tree-ring studies are often obtained using
chainsaws and, less frequently, 2-person crosscut saws. Saw marks on cross-sectional wood samples
can be quite deep and uneven, and sanding rough-cut wood cross-sections is inefficient in terms of
processing time and wear on sanding belts. Trimming rough-cut wood samples with a band saw or
treating with a surface planer creates a smoother initial surface for sample sanding and polishing.
Sample trimming with a band saw or surface planer is also useful for post-analysis archiving and wood
storage, when excess wood can be removed and smaller samples entered into storage. Band saw and
surface planer safety techniques are also discussed.
Keywords: sample preparation, cross-section, band saw, surface planer, methods, archival wood,
trimming.
INTRODUCTION
Previously published research reports and
manuscripts have formally articulated many sam-
ple preparation practices commonly used in tree-
ring research (Yamaguchi and Brunstein 1991;
Orvis and Grissino-Mayer 2002; Grissino-Mayer
2003; Sheppard and Witten 2005). Research
reports such as these are critically useful for
methods training and communication, especially
in light of the recent proliferation of dendrochro-
nology labs and the global surge in popularity of
tree-ring methods. Despite a fairly robust pub-
lished record of tree-ring sampling and prepara-
tion techniques, several widely used references
(Arno and Sneck 1977; Schweingruber 1988; Speer
2010) do not discuss the rationale for and
techniques used to trim cross-sectional samples.
Additional authors who do refer to sample
‘‘trimming’’ (removal of thin surface veneer or
excess wood) using a band saw in the Methods
sections of their papers do not articulate how or
why they chose this technique (Stokes and Smiley
1968; De Visser 1992; Kaye and Swetnam 1999;
Bortolot et al. 2001; Fichtler et al. 2003). Surface
planing as a sample preparation technique has not
been formally described in the tree-ring literature.
Saw marks on cross-sectional wood samples
from chainsaws and crosscut saws can be quite
deep and uneven. This is particularly true if the
sample was collected using imperfectly maintained
equipment or if the saw was handled by an
inexperienced sawyer. Improperly sharpened saws
may have a tendency to cut a curve in a particular
direction, creating a convex or concave surface on
the wood sample. Even a well-maintained chainsaw
will routinely produce grooves on a sample surface
as much as 2 mm deep. Poorly-trained or in-
experienced sawyers may fail to cut evenly,
particularly on trees requiring multiple cuts. Mis-
matched cuts can create deep vertical saw marks in
the sample (kerf), whereas mismatched horizontal
cuts can produce thin veneers or angled kerfs that
pose a difficulty to sample preparation. Convex
and concave sample surfaces pose additional
difficulty for proper sanding and polishing, and if
*Corresponding author: jminor@email.arizona.edu
TREE-RING RESEARCH, Vol. 71(2), 2015, pp. 130–134
DOI: http://dx.doi.org/10.3959/1536-1098-71.2.130
130 Copyright 2015 by The Tree-Ring Society
left untrimmed, require additional expenditures of
time and materials during sample preparation.
Further, uneven sample surfaces provide difficulties
when using a binocular light microscope for dating
rings, scars, and other features of interest, as the
technician must constantly refocus the microscope
as the wood sample is moved below it. Sample
preparation is more efficiently accomplished if the
sample surfaces are trimmed or planed and
smoothed prior to polishing with progressively
finer-grit sandpaper. This paper fills a gap in the
published literature about the efficacy, methods,
and rationale of trimming samples with a band saw
or smoothing cross-sectional surfaces with a surface
planer prior to sanding and polishing, and intro-
duces associated safety considerations.
MATERIALS
A large, floor-mounted band saw (e.g. Rock-
well/Delta, Figure 1; cost approximately $1800
USD in 2015) provides the optimal combination
of smooth sample surface and user safety. Floor or
table-mounted band saws are heavy and stable and
are equipped with an adjustable blade guard, which
improves user safety. A cross-sectional wood
sample surface trimmed with a band saw will
generally have , 0.5 mm deep grooves (Figure 2a)
roughly equivalent to the surface produced by
sanding with 36 grit sandpaper (Orvis and Gris-
sino-Mayer 2002). Wood samples featuring mis-
matched chainsaw cuts can contain grooves greater
than 2 mm and kerf marks exceeding several
centimeters. Poorly cut wood samples can contain
grooves greater than 2 mm and kerf marks
exceeding several centimeters (Figure 2b).
Large, floor-mounted band saws are
equipped with an adjustable blade guard that
can be set higher and lower depending on the size
of the wood sample being cut (Figure 1). Maxi-
mum blade guard height influences the size of
wood that can be trimmed using the band saw,
and are commonly manufactured in sizes of 50.8
cm (20 inches) and 35.56 cm (14 inches). A band
saw allows users to both rip and cross-cut wood,
which is essential for trimming away unwanted
material. Saws designed for cross-cutting wood
Figure 1. Trimming rough-cut surface and unsound wood from
a mounted cross-section. Adjustable blade guards on high-
quality band saws promote user safety, as do personal
protective equipment (ear and eye protection and a dustmask)
and proper technique, such as ‘‘push sticks.’’
Figure 2. (A) Pinus leiophylla sample surface showing very
shallow kerf marks (equivalent to 40 grit sandpaper) following
band-saw trimming. (B) Mismatched cuts create surfaces that
are very difficult to sand without prior trimming.
Trimming Wood Samples for Preparation and Storage 131
grain are not suitable for ripping wood (cutting
with the grain). Band saws can rip and cross-cut
wood, and thus provide a considerable advantage
in this respect.
Hand-held surface planers (cost approxi-
mately $150 USD in 2015) provide another
technique for smoothing cross-sectional samples
prior to sanding and polishing. As with a band
saw, cross-sectional samples treated with a surface
planer will have grooves of less than 0.5 mm, with
sound wood producing very smooth surfaces.
Unlike a band saw, surface planers do not limit
the size of cross-sections that can be processed,
which is especially important for large round
samples or eccentrically shaped cross-sections
commonly encountered in fire history studies.
METHODS
Band saws are principally useful for two
types of trimming operations: cutting cross-
sectional slices and making tangential cuts. Cross-
sectional (transverse) trimming is used to cut away
the rough surface created by a chainsaw or
crosscut saw during sample collection. Transverse
trimming can also be used to decrease the
thickness of a field-cut sample, or to target
anatomical or other features of interest in the
sample. Transverse trimming can also be used to
make the field cuts parallel for better viewing
under a microscope, such as when wedge samples
are cut with a crosscut saw or with a chainsaw
without having made plunge cuts (e.g. methods
first proposed by Arno and Sneck 1977). Improv-
ing the parallelism of field cuts reduces distortions
in tree-ring widths and cell dimensions by placing
transverse surfaces more perpendicular to the
longitudinal stem axis. Surface planers can also
be used to improve sample parallelism, but require
considerably more time to remove an equivalent
amount of wood compared to a band saw.
Longitudinal cutting (ripping) is another
useful technique accomplished with a band saw.
Longitudinal cuts can be used to separate espe-
cially large or unwieldy samples into multiple
pieces. Tangential cuts provide another useful
technique for cutting away unnecessary wood, or
for minimizing the amount of wood in a sample.
Round samples, and particularly small-di-
ameter ‘‘cookies’’ must be treated with particular
caution when trimming with a band saw, as the
high blade speed has a tendency to catch and spin
small round samples and poses a risk to the saw
operator. A fast-moving band saw blade can
throw small and round samples at the saw
operator or others nearby, or the sample can turn,
thereby kinking and destroying or even breaking
the band saw blade. If it is necessary to trans-
versely trim small-diameter ‘‘cookie’’ samples,
a tangential surface can be cut onto the side to
provide stability to the sample as the transverse
(cross-sectional) surface is trimmed. Cutting this
flat surface does provide a more stable and safer
base for the sample to rest upon, but may come at
the cost of some of the outermost rings on one side
of the wood sample. Another possibility for safely
cutting rounds is to build a jig of braced triangular
pieces of scrap wood that can be wedged against
the round sample, or screwed to the sample to
prevent rotation while cutting.
Surface planers cannot be used to trim
samples transversely or tangentially, but are useful
for smoothing cross-sections prior to sanding and
polishing. The initial step for cross-section sample
preparation is to flatten especially high ‘‘peaks’’
from the field cut surface. Once the sample surface
is approximately flat and level, the surface planer
can be used to smooth out saw marks and other
irregularities. Cutting depth should be set fairly
shallow, to avoid gouging out too much wood and
thereby increasing processing time. Because of the
mechanical action of the cutting blades, care
should be taken when working near fragile edges
of the cross-sectional sample, as the surface planer
can knock external scars or loose pieces of wood
from the sample, unless these are secured prior to
surfacing (i.e. Hook et al. 2013).
To hold cross-sectional samples in place
while smoothing with a surface planer, samples
should be placed on a peg-board table with short
dowels arranged around the sample or the sample
backing to prevent the cross-section from moving
underneath the machinery. For straight-edged
samples or samples mounted to a backing, a square
jig can be constructed to hold the sample in place
(Figure 3). This technique is also recommended
132 MINOR and ARIZPE
for securing samples while sanding with a belt
sander or orbital sander.
Band saws and surface planers should always
be operated by users who have received proper
training and who are wearing personal protective
equipment, which at a minimum should include
eye protection or a face shield, and also ear and
dust protection (e.g. Figure 1). It is highly
recommended that ‘‘push sticks’’ be used for
advancing the wood sample through a band saw
to increase the distance between the saw operator
and the band saw blade (Figure 1).
DISCUSSION
Beyond the benefits of post-trimming sample
sanding and polishing discussed above, band-saw
trimming also allows researchers and technicians
to reduce the size of samples. A common field
technique is to collect thick samples of unsound
wood, to preserve delicate features that might
otherwise be lost in transit. Thick samples of
sound wood can be trimmed down using a band
saw prior to sanding and polishing. Special
techniques for preparing and surfacing unsound
wood, subfossil wood, and archaeological char-
coal have been presented by Hook et al. (2013)
and Schweingruber (1990). Fragile cross-sections,
including fire history samples and subfossil wood,
can be glued to a sturdy backing to prevent loss of
external features (Figures 1 and 3). Band-saw
trimming also allows researchers and technicians
to target features along the longitudinal axis of
a wood sample for presentation, such as pith,
outermost rings, or scars not present throughout
the width of a collected sample.
The capability to trim and adjust sample sizes
becomes critical during post-research sample archiv-
ing, when space considerations and their associated
square-footage costs become important (Creasman
2011). Fitting samples into archival-quality storage
boxes is efficiently accomplished with band-saw
trimming, because excess wood can be removed from
the sample following dating and analysis.
Furthermore, good-quality band saws such as
a Rockwell/Delta (Figure 1) or hand-held surface
planers are equipped with dust-handling capabil-
ities, which can be integrated into larger shop-level
dust and air handling systems. Dust control is an
essential consideration for wood shops and sample
preparation areas, as dust production can increase
fire and explosion hazards, and can impair worker
health.
ACKNOWLEDGMENTS
We would like to thank Kit O’Connor, Chris
Guiterman, and two anonymous reviewers for
helpful comments.
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Received 27 October 2014; accepted 31 March 2015.
134 MINOR and ARIZPE
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