Note: Descriptions are shown in the official language in which they were submitted.
`" ~Lf~3~26
Field of the Invention
The present invention relates to the clipping of
peeled veneer into discrete portions, more particularly the
present invention relates to a system for clipping taper
peeled veneer having one side edge longer than the other,
by adjusting the angular position on one or more clipping
knives relative to the path of travel to compensate for the
curving of the veneer.
Backaround to the Present Invention
In the production of veneer particularly for the
manufacture of plywood, it is customary to peel a bolt of
wood on a lathe using a cutting edge substantially parallel
to the axis of rotation of the bolt thereby to produce a
length of veneer with both side edges essentially the same
length so a uniform thickness veneer with little or no
tendency to curve is produced.
A system has recently been devised ~or tapered
peeling veneer to increase the yield from a log or bolt and
improve, for some purposes, the quality of the veneer being
produced. Such a system is described in U.S. Patent
4,732,183 issued March 22, 1988 to Barnes.
When veneer is peeled on a taper as defined in
the Barnes application the side edge of the veneer cut at
the larger diameter end of the bolt is longer than the side
edge of the veneer formed from the smaller diameter end of
the bolt. Veneer cut in this manner tends to curve and
cannot be clipped in the conventional manner if the main
advantages of tapered peeling are to be better ensured.
~.
~Z93~ 6
In a companion application by R.M. Knudson
(Canadian Application Serial No. 563,666) filed on the same
day as this application a system of clipping is described
wherein full or partial panels or sheets are formed by
clipping. A clipping knife is angularly adjusted relative
to the axis of rotation of the block during peeling to clip
full panels with thin sides parallel and partial panel with
thin sides at an acute angle. These partial panels are
preferably half panels so that two can be coupled together
(after rotation 180) to form a full panel having parallel
side walls and thereby minimize waste.
Brief Description of the Present Invention
It is an object of the present invention to
provide a clipping system for curved veneer formed by taper
peeled wherein a clipper knife is adjusted as the veneer
travels therepast, to reorient the knife relative to the
axis of rotation of block into a position to clip the
curved veneer substantially radially oE the curvature of
the peeled veneer adjacent the clip.
Broadly, the present invention relates to
clipping a curved veneer having one curved side edge longer
than the other curved side edge into discrete segments each
defined by pair of opposed curved side edges one longer
than the other and a leading and trailing end edge
comprising peeling a block of wood rotating on an axis
using a peeling edge, adjusting the angle of a clipper
knife to said axis of rotation to clip the veneer into
; discrete panels each having its leading and trailing edges
substantially radial to the curvature of the veneer at the
location of each of said leading and trailing edges.
The present invention will normally comprise
means for sensing a bolt to determine the size (diameter)
of the bolt and its taper, means to position said bolt for
rotation on an axis of rotation based on the size and
~2~3~Z6
taper of said bolt sensed by said sensing means, means to
rotate said bolt on said axis of rotation, a peeling
knife, means to adjust the angle of said peeling knife to
the axis of rotation of said bolt in accordance with the
sensed taper of said bolt thereby to peel d veneer having
a longer and a shorter curved side edge, a clipper knife
closely coupled relative to said peeling knife and located
along the path of travel of said veneer from said peeling
knife, computer means for determining the curvature of at
least one of said longer or shorter curved side edges
based on the size of said bolt9 the cutting angle of said
peeling knife and the position of said peeling knife,
means to angularly adjust said clipper knife to extend
substantially radially of the curvature of said veneer
adjacent said clipper knife when said clipper knife is
actuated to clip said veneer into sheets.
Brief Description of the Drawings
Further features, objects and advantages will be
evident from the following detailed description of the
preferred embodiments of the present invention taken in
conjunction with the accompanying drawings in which:
Figure 1 is a schematic illustration of the
operation of the present invention.
` 25 Figure 2 is a schematic plan view of a lathe
adapted to cut on a taper close coupled with a clipper
incorporating the present invention.
Figure 3 is a schematic plan view of a clipper
employing two relatively moveable clipper knives for
cutting veneer at different angles.
Figure 4 is a plan view of a continuous sheet of
veneer illustrating one clipping strategy incorporating
the present invention.
~:
~L~93~;~6
Figure 5 is a view similar to Figure 4 showing a
; modified strategy.
Figure 6 is a plan view of a panel clipped in
accordance with the strategy of Figures 4 or 5 of the
present invention.
:~'
Figure 7 is a schematic of a further clipping
strategy using a pair of clipper knives as illustrated in
Figure 3.
Figure 8 is a plan view of a panel clipped using
the strategy illustrated in Figure 7.
Description of Preferred Embodiments
Figure 1 schematically illustrates via a box
diagram various steps to accomplish the desired results of
the present invention. In the preferred arrangement, the
wood bolt to be processed is first sensed in sensing and
positioning station I wherein the diameter of the bolt is
' determined as well as its taper shape. The bolt is then
positioned in accordance with the information obtained at
station number 1 and mounted in the centering and rotating
section II with the selected longitudinal axis of the bolt
forming the axis of rotation. The peeling knife feed
indicated by box III is controlled in accordance with the
axis of rotation of the bolt so that the cutting edge of
the knife is correlated with the taper of the bolt to
position the cutting edge of the knife at an angle to the
axis of rotation and peel a veneer that is longer on one
side than the other. This veneer then clipped in clipping
station IV in a selected pattern as will be described in
more detail hereinbelow. The computer station V correlates
the input from the various stations to control the opera-
tion of the station to cut and clip the veneer.
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iL2~3~4~6
Devices represented by the boxes I, II and III
- may be essentially the same as those described in said
8arnes application, however, the clipping station IV which
forms an important portion of the present invention is
significantly different dS is the computer station V which
must also control the clipping station IV.
Referring to Figure 2 the general layout of the
various stations is shown in more detail. ~ood bolts are
fed to the lathe 10 on a suitable infeed layer 12 in a
direction as indicated by the arrow 11 with their longi-
tudinal axes substantially perpendicular -to the direction
of travel 11. The bolts first pass into a sensor 14 that
determines the size and shape of the bolt, i.e. the
I diameter and taper. The bolt is then oriented via a
! 15 positioner 16 on a selected axis of rotation based on
, information sensed by sensor 14 and then moved into posi-
3 tion in the lathe where it will be rotated for peeling.
In this case the bolt is oriented and positioned by posi-
tioner 16 between movable chucks schematically indicated
as 18 and 20 mounted in the frame 22 of the lathe for
axially movement as indicated by the arrows 24 and 26
rotation as indicated by the arrows 28 and 30. A bolt as
such indicated at 32 is held in and rotated by the chucks
18 and 20 on its rotational axis as indicated at 34.
The information obtained in the sensor 14 is
used to position the bolt 32 in the chucks 18 and 20,
i.e. align the selected longitudinal axis of the bolt on
the rotational axis 34 defined by the lathe chucks 18 and
20.
Control computer 36 receives information via
line 38 from the sensor 14 and controls the feed of peel-
; ing knife schematically illustrated at 40 in accordance
with the sensed shape and axis of rotation 34. The peeling
knife 40 is mounted on knife carriage 42 the opposite ends
of which are mounted on sides 44 and 46 respectively.
-- 5
12~ 6
The block 44 is driven by a suitable drive such
as a hydraulic cylinder means 48 and piston rod 50 which
is connected to the block 44 to move the block 44 toward
! and away from the axis of rotation 34 of the bolt 32 as
indicated by the arrow 52. Movement of the shaft or piston
rod 50 is measured by a suitable measuring means 54 which
communicates this information to the control computer 36
so that the position of the block 44 is known. Similarly,
the hydraulic cylinder 56 operates the shaft or piston rod
58 to move the block 46 toward and away from the axis 34
as indicated by the arrow 60. The sensor 62 senses the
movement of the piston rod 58 and this information is fed
to the control computer 36 via line 64 so that the posi-
tion of the block 46 is known.
The control computer 36 independently controls
via lines 66 and 68 the hydraulic cylinders or drives 48
and 56 respectively so that each end of the knife 40 is
; independently advanced and the angle of the cutting edge
70 of the knife 40 is adjusted relative to the axis of
rotation 34 of the bolt 32 so the knife 40 peels at the
desired angle to the axis 34.
When a tapered log or bolt 32 is centered for
rotation on rotational axis 34 the knife blocks 44 and 46
are independently advanced to bring the cutting edge 70
into proper cutting angle relative to the axis 34 in
accordance with the information provided by the sensor
14. With the larger end of the bolt 70 mounted in the
chuck 20 the block 44 is advanced toward the axis 34 rela-
tive to the block 46, i.e. to the dash line position
illustrated in Figure 2 so that the cutting edge 70 is now
~; at an angle A to the axis 34. This angle A is determined
; by the shape of the log or bolt 32 turning in the lathe as
described in the said Barnes application to peel either a
uniform thickness veneer or tapered cross-section veneer
widening from the small diameter end of bolt 32 toward the
larger diameter end of bolt 32.
- 6 -
~ 33~
Cutting edge 70 will normally be in the horizon-
tal plane containing the axis 34 and the angle A is
measured in that plane.
The angle A may be adjusted in accordance with
various scenarios as defined in the said Barnes applica-
tion, however, the present invention is concerned with
those scenarios wherein the angle A is an acute angle and
the bolt 32 is cut on a taper so that the veneer schemati-
cally illustrated at 72 has a long edge 74 and a shorter
edge 76 with longer edge 74 being cut at the end of the
knife 40 adjacent to the larger diameter end of the block
or bolt 32, i.e. at the maximum radius of the taper cut,
and the shorter edge 76 formed at the opposite end of the
knife 40, i.e. at the end of the knife 40 closer to the
axis of rotation 34.
The clipper indicated at 80 includes a clipper
knife schematically illustrated at 82 moved to and from
clipping position via a motor or the like indicated at 84
the timing of which is controlled by the computer control
36 via line 86 as will be described in more detail herein-
below.
- Clipper mechanism particularly the blade 82 is
mounted in a suitable manner so that its angular relation-
ship to the path of travel of the veneer 72 can be adjust-
ed as required, i.e. change its angle to the path of
travel as indicated by the arrow 88 of a veneer cut with
the peeling edge 70 substantially parallel to the axis of
rotation 34, i.e. in the path 88 is substantially perpen-
dicular to the axis 34.
In the illustrated arrangement this angular
adjustment is obtained by mounting the clipper 80 on the
frame 22 on a pivot pin 90 to the frame and pivoting the
clipper 80 on the axis 90 by a piston and cylinder 92
connected to an arm 94 extending from the clipper 80. The
operation of the piston and cylinder 92 is controlled Vid
~3~
the control computer 36 through line 96 to move the arm 94
dS indicated by the arrow 95 thereby angularly positioning
-the blade 82 relative to the path of travel 88 in d manner
that will be described in more detail hereinbelow.
As schematically illustrated the clipper 80 may
be mounted in other ways and the pivot pin 90 be eliminat-
ed. For example the clipper 80 may be mounted so that both
ends may be individually moved by eliminating pivot pin 90
and providing an extension arm 98 connected to a piston
and cylinder 100. The operation of the piston and cylinder
100 is controlled by the control 36 via line 102 to move
the arm 98 as indicated by the arrow 104. In the latter
arrangement the angular position of the clipper 80 and
thereby the knife 82 relative to the path of travel 88 is
'I controlled by the coordinated movement or operation of the
piston and cylinder 92 and 100 as will be described in
more detail hereinbelow.
The system shown in Figure 3 is similar to that
shown in Figure 2 however a second clipper 200 has been
added. This clipper 200 will be essentially the same as
the clipper 80 and will have a knife 202, and an actuator
204 controlled by computer 36 as indicated by the line
206. The clipper 200 is angularly adjustable relative to
the axis 34 independent of the angular adjustment ~f the
clipper 80 by means such as the piston and cylinder
arrangement 208 operation of which is controlled by the
computer 36 as indicated by the line 210. Movement of the
clipper 200 is obtained through the connection between the
piston cyliner 208 and arm 212 extending from the clipper
200. The action of the piston and cylinder pivots the
clipper 200 around the axis 214.
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~33426
Alternatively the clipper 200 may be mounted via
pistons and cylinders at op~osite ends as described herein
above with respect to piston and cylinder 100 and the arm
98 for the clipper 80 i.e. the pivot pin 214 will be
eliminated and a separate piston and cylinder provided to
position the opposite end of the clipper.
Yet another alternate way of adjusting the
angular relationship of the knife 200 to the axis of
rotation 34 would be to eliminate the piston and cylinder
10208 and replace it with a piston and cylinder 216 operat-
ing between the ends of the clippers 80 and 200 to pivot
the clipper 200 around the axis 214 under control of the
computer 36 which controls the piston cylinder 216 via
line 218. Basically the piston cylinder 216 changes the
15angular relationship between the clipper knife 82 and 202
so that the precise angle of clipper knife 202 to the axis
34 is controlled by the combined operation o-F the piston
and cylinder 92 and the piston and cylinder 216.
Various strategies for operating the clipper are
disclosed.
` In the arrangement shown in Figures 4, 5 and 6
only the clipper 82 will be used. In this arrangement a
first panel 300 is formed by first clip numbered 1 and a
second clip 2. These clips 1 and 2 are substantially
parallel to a radius R1 which is essentially on a radial
line based on the curvature of the veneer at the mid point
of panel 200. Thereafter panels 400, 500 etc, the clip 3
which defines one side of panel 400 and a side of panel
500 is along a line substantially parallel to the radius
through the mid point of panel 400 clip 4 which defines
one side of panel 500 and of panel 600 is substantially
parallel R3 which is the radius at the mid point of the
panel 500 etc.
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3~26
In a more practical arrangement as shown in
Figure 5 each of the clips defining the sides of the
panels are clipped along a radius based on the curvature
of the veneer sheet at or adjacent to the clip line i.e.
clip lA would be radial to the leading end of the veneer
being peeled based on the curvature of the veneer at that
point. Clip 2A defining the other side of panel 300 from
the side defined by clip lA could be substantially radial
to the curvature of the veneer at the clip line and
similarly clip lines 3A, 4A etc will all be substantially
radial based on the actual curvature of the veneer at or
adjacent each of the respective clip lines.
It will be apparent that this procedure does not
produce a rectangular panel or sheet for laying up to form
a plywood laminate and the sheet must be cut bigger than
that required for producing a laminate so that it rnay be
! trimmed as indicated for the sheet 300A in Figure 6 by
trimming along the lines 301, 302, 303 and 304. The lines
301 and 303 are substantially parallel as are the lines
! 20 302 and 304 and the lines 302 and 304 are perpendicular to
` the lines 301 and 303.
It is not necessary to do all of the trimming
operations before laying up. For example it is only
necessary to cut a first trim line such as trim line 301
which can then be used as a datum edge for guiding the
panel through the layup system and press with the final
-trimming taking place in the normal trimming operation in
the plywood mill i.e. trim cuts 302, 303 and 304 would be
performed after the sheet 300A has been added to other
sheets to form a layup for plywood and the plywood trimmed
to its final size.
In Figure 7 a modified technique for clipping is
illustrated. In this arrangement clipping mechanism
schematically illustrated in Figure 3 is employed.
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At the beginning the first edge lB may be cut by
either the knife 82 or the knife 202 may be used. This
initial cut will normally be substantially radial to the
curvature of the veneer at the line of cwt or as above
indicated could, for example, be parallel to the radius at
the mid point of the panel 300B.
In any event the next cut or clip 2B must be
performed by the clipper closest to the axis of rotation
34 of the bolt. This clip line 2B will be substantially
parallel to the initial cut lB and will define the
; opposite side of the panel 300B to the side defined by the
clip line lB.
The clipper knife 202 preferably will be orient-
ed to be substantially radial to the curvature of the
veneer at the location of the clip line 38 thus there will
be d correction C at the longer edge 74 the veneer 72.
This correction C will be determined by the difference in
angular relationship between the cuts 2B and 3B which will
align the cut 3B to be substantially radial relative to
' 20 the curvature of the veneer 72 or as above described for
! example parallel to the radius at the mid point of the
panel or sheet 400B, one side of which is defined by the
clip 3B. The clip 3B will be formed by the clipper knife
202 i.e. a knife farthest away from the axis of rotation
34 so that the clipping operation separates the substan-
tially triangular waste piece 700 from the leading end of
the sheet extending from the lathe rather than attempting
to separate the waste piece from the discreet panel.
The next clip line 4B will be formed by the
clipper knife 82 and the clipper knives 82 and 202 will
operate alternatively as long as there is a triangular
waste sheet being formed. If the veneer becomes relatively
straight and no triangular waste sheet is formed then only
one clipper need be used.
g34Z6
In any event the clip 4B will be substantially
parallel to the clip 3B so that the clips 3B and 4B define
opposite parallel edges of the veneer sheet 400B.
The next clip 500B will be performed by the
knife or cutting edge 202 at an angle (radial to the
curvature of the veneer) so there is a triangular waste
sheet 800 formed between the clips 4B and 5B and the ends
of the clip lines 4B and 5B at the larger radius side of
the veneer 72 will be spaced by a distance correction C1.
Obviously the clip line 5B forms one side of the
panel SOOB and the opposite side will be formed by a clip
line substan-tially parallel to the clip line 5B and this
process will be continued so that discreet sheets with
substantially parallel side edges will be formed and these
sheet can then be fed directly (without further clipping
to provide a datum edge) into the plywood mill.
If the grain angle in the sheet is not important
for the particular use to which the veneer is to be put,
then the system illustrated in Figures 4 and 5 is probably
; the simplest mode of operation. One of the side edges of
the panel say side edge 1 or lA for the panel 300 or 300A
; 25 may be used as a datum and the panel fed through the
plywood equipment using that edge as a guiding edge.
Obviously this arrangement would not result in the grain
direction being parallel to a longitudinal axis of the
resultant plywood panel although it may be acceptable.
For aesthetic reasons and in some cases strength reasons
it is preferred to have the grain direction aligned with
the longitudinal direction of the fabricated or laminated
plywood material and for this reason the datums should be
substantially parallel to the average grain direction in
each discreet sheet.
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` lZ9~4;21Ei
Table I indicates the length of veneer cut from
a log or bolt with the cutting edge 70 at an angle A to
the axis of rotation 34 wherein the length of the veneer
in the grain direction is about 2.6 m; the large d1ameter
end of the bolt adjacent to the chuck 20 is about 356 mm,
the small diameter of the bolt adjacent to the chuck 24 is
about 381 mm; and a tapered thickness veneer is cut having
a thickness at the larger diameter end of the bolt of
about 2.7 mm~ and at the smaller diameter end of the bolt
of about 2.4 mm for a nominal veneer thickness of 2.5 mm
(i.e. an average thickness of 2.5 mm).
; TABLE I.
Small end Bolt Diameter, mm = 356
Large End Bolt Diameter, mm = 381
Minimum Core Diameter, mm = 101
Nominal Veneer Thickness, mm = 2.5
!
~;, 20
Small End Large End
Veneer Core Edge Veneer Core Edge Length
Rev Thick Dia Length Thick Dia Length Difference
No. mm mmmm mm mm mm mm
1 2.413 3S31110 2.667 378 1189 -79
2 2.413 3481094 2.667 373 1172 -78
3 2.413 3441079 2.667 368 1155 -76
4 2.413 3391064 2.667 362 1138 -74
5 2.413 3341049 2.667 357 1122 -73
6 2.413 3291034 2.667 352 1105 -71
7 2.413 3241019 2.667 346 1088 -69
8 2.413 3191003 2.667 341 1071 -68
9 2.413 316988 2.667 336 1055 -67
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.
Small End Large End
Veneer Core Edge Veneer Core Edge Length
Rev Thick Dia Length Thick Dia Length Difference
No. mm mm mm mm mm mm mm
Continued
10 2.413 310 973 2.667 3301038 -65
11 2.413 305 958 2.667 3251021 -63
12 2.413 300 943 2.667 3201004 -61
13 2.413 295 928 2.667 314 987 -59
14 2.413 290 912 2.667 309 971 -S9
15 2.413 286 897 2.667 304 954 -57
16 2.413 281 882 2.667 298 937 -55
17 2.413 276 867 2.667 293 920 -53
18 2.413 271 852 2.667 288 904 -52
19 2.413 266 837 2.667 282 887 -50
20 2.413 261 822 2.667 277 870 -4
21 2.413 257 806 2.667 272 853 -47
22 2.413 252 791 2.667 266 837 -46
23 2.413 247 776 2.667 261 820 -44
24 2.413 242 761 2.667 256 803 -42
25 2.413 237 746 2.667 250 786 -40
26 2.413 233 731 2.667 245 770 -39
27 2.413 228 715 2.667 240 753 -38
28 2.413 223 700 2.667 234 736 -36
29 2.413 218 685 2.667 229 719 -34
30 2.413 213 670 2.667 224 703 -33
31 2.413 208 655 2.667 218 686 -31
32 2.413 204 640 2.667 213 669 -29
33 2.413 199 624 2.667 208 652 -28
34 2.413 194 609 2.667 202 636 -27
35 2.413 189 594 2.667 197 619 -25
36 2.413 184 579 2.667 192 602 -23
- 14 -
~33~Z~;
Small End Large End
.
Veneer Core Edge Veneer ~ore Edge Length
Rev Thick Dia Length Thick Dia Length Difference
No. mm mm mm mm mm mm mm
. _ . . .
Continued
37 2.413 179 564 2.667 186 585 -22
38 2.413 175 549 2.667 181 569 -23
39 2.413 170 533 2.667 176 552 -19
40 2.413 165 518 2.667 170 535 -17
41 2.413 160 503 2.667 165 518 -15
42 2.413 155 488 2.667 160 502 -14
43 2.413 150 473 2.667 154 485 -12
44 2.413 146 458 2.667 149 468 -1~
45 2.413 141 442 2.667 144 451 -9
46 2.413 136 427 2.667 138 434 -7
` 47 2.413 131 412 2.667 133 418 -5
48 2.413 126 397 2.667 128 401 -4
` 49 2.413 122 382 2.667 122 384 -2
50 2.413 117 367 2.667 117 367 0
- 51 2.413 112 352 2.667 112 351 +1
52 2.413 107 336 2.667 106 334 +2
53 2.413 102 321 2.667 101 317 +4
Total Length of Veneer on Small End = 37915 mm
Total Length of Veneer on Large End = 39903 mm
It will be apparent from Table I that the
cutting angle Angle A is constantly changing as the
diameter of the bolt changes thereby gradually reducing
; the difference of length between the long edge ~large end
edge) 74 and the short edge (short end edge) 76 of the
~ - 15 -
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veneer 72 for each rotation of the bolt. Compare, for
example, the first revolution which provides a length
difference of about 79 mm with say the 25th revolution
which produces a length difference of only 41 mm.
Thus, the amount of correction necessary (angle
of the clipping knife to the axis of rotation of the bolt)
is reduced as peeling continues.
Table II, is an example of five consecutive
clips illustrating one example of how a correction may be
applied based on the five clipping strategies. In the
particular example shown in Table II clip number 1 is the
starting clip which is radial relative to the initial
curvature of the veneer.
TABLE II.
Min Arc
Length Diff.in
from Edge
Clipping Prev Lengths
` Cut No. Cut, m mm
lA --Starting Cut--
2A 1.3 94
3A 1.3 94
4A 1.3 92
5A 1.3 92
As indicated in Table II in following the prac-
tice described in relation to Figure 5 the difference in
edge lengths i.e. between the long edge 74 and the short
76 for each panel is indicated i.e. clip 2A which is
defining one side of panel 300A cuts the edge 76 94 mm
- 16 -
~ ~ zg34~6
closer to edge lA then it traverses the edge 74. Similarly
edge 3A traverses edge 76 94 mm closer to clip 2A than it
is when measured along the longer curved edge 74 so that
the panel 300A and 400A are each narrower by 94 mm at
their edge formed by the minimum radius edge 76 than the
edge formed by the maximum radius edge 7~ measured along
the curved edges 74 and 76.
If the clipping strategy of Figure 7 were used
then the length C would be 94 mm as would the length C1
whereas the following two corrections would be 92 mm i.e.
for the clips 4A and SA in Table II.
It will be apparent that when defects are
~ 15 present in the veneer and the clipper is triggered in the
! conventional manner the procedure of the present invention
will be reinstated after the defect is removed ~the clips
to remove the defect will when practicing the present
invention normally be made with the clipper blade at the
appropriate angle - radial to help in correcting for the
differences in length of the two sides of the veneer).
;~ .
Having described the invention modifications
will be evident to those skilled in the art without
departing from spirit of the invention as defined in the
appended claims.
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