Note: Descriptions are shown in the official language in which they were submitted.
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l~IELD OF IL~ JTI;):~
This invention relates to tsle ~anufacture of
clear grade wood mouldings. In particular, this invention
relates to a method of convertin~ a longitudinally
elongated moulding rip having a flaw containin~ portion
therein into a flawless premi~ length clear grade moulding.
PRIOR ART
~ ood mouldings are currently manufactured in
both "paint grade" and "clear grade" quality. The "paint
~rade" mouldings are mouldings which are intended to be
painted upon installation~and consequently the quality
of the surface finish of the moulding is not important.
Paintgrade mouldings tend to be inexpensive mouldings
and are not the type of moulding to which the present
invention relates. "Clear grade`' or '`natural grade"
mouldings are mouldings in which the surface finish must
be substantially free of flaws such as those resulting
from the presence of a '`knot'`.
Moulding manufacturerc; customarily obtain good
quality lumber for use in the ~anufacture of "clear grade"
- mouldings, Generally, the moulding rip of the quality
used for producing clear ~rade mouldin~ will have an
avera~e length of aboutt~elve feet and will contain no
more than two flaws.
In the present method of manufacturing mouldings,
the board which is purchased by the moulding manufacturer
is cut into rips of approximate width required by the
moulding, the rips are then worked to provide the required
mould profile and if flaws are present, the portions`
~0 containing the flaws are cut out of the length. Conse-
quently, the manufacturer finds that from any particular
batch o~ lumber wh:ich he machines in tAe conventional
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manner he produces a nun~er o~ leng~hs measuring seven
feet and over, all of whicll he can classify as "premium
lenath" lur~er and a number of lengtns which are less
than seven feet but fall within the range of about three
to six feet whicn are ~nown as "shorts",
If the purchaser is prepared to pay a premium
price, which may be about 20% greater than the standard
lineal price for mouldings, he may be able to obtain
mouldings all of which are of the "premium length" that
is to say, seven feet or over. In some instances, a
purchaser may be prepared to pay this additional price
~nowing that "shorts" are no value to him in a particular
application.
By far the greatest volume of moulding sales are
those in which the purchaser i5 prepared to pay the standard
lineal price for mouldings ancl as a result of which he is
required to accept up to 20Q shorts in any one order, As
previously indicated, shorts are lengths measuring from
tnree to six feet. Irhe remainder of the load will be of
the "premium len~th".
In n~st instances, the purchaser would prefer to
receive all of the order in units o the'premium length",
however, he accepts the load including the silorts in order
to avoid payment of the "premium price". In many instances,
the shorts cannot be ef~ectively used and are merely
discarded as waste~
Despite the fact that the desirability of providing
mouldings in the "premi~ length" has been ~nown for some
considerable time, the industry has continued to accept
the practice of including "shorts" in a standard load.
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In the production of "paint grade" mouldings,
- it is known to use a "finger joint'` to connect "shorts`'.
The "finger joint" is however quite unsuitable for
use in the production of clear grade mouldings because in
tne forming of the profile of ~e moulding, various portions
of the mating fingers of the joint are exposed thereby
creating a disruption in the pattern at tne face of ~le
moulding which is not acceptable in "clear grade'` mouldings
becaus~ these mouldings are generally finished in a manner
which will permit the grain of the ~ood to be visible
at the surface of the moulding.
~ "scarf joint" is a joint w;~ich is known to
s~illed carpenters and has been used by s~illed carpenters
for connec:ting lengths o mouldings at a job site in order
to provide lengths suitable for use in finishing a room
or the like, particularly where the length required is
greater than the "premium length'`. This practice has,
however, relied to a very large extent on ~le s~ill of
the individual carpenter and is not widely used because
considera~le skill i5 required in order to make an effective
scarf joint. Consequently, in most cases a simple butt
joint is made by a carpenter in present day installation
where a joint is necessary. The scarf joint requires a
very precise cutting of ~le moulding in a plane which is
~` angularly inclined in two directions with respect to the
lon~itudinal extent of the moulding. Because of the
complexity of the scarf joint, it is not widely used in
the installation of mouldings. It is to be noted that
the use of a scarf joint in this application is limited
to a joint made by a carpenter in a finisiled moulding. To
the best of my knowledge a scarf joint has not previously
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been use~ in a preliminary step in the manufacture of
moulding prior to the machining of the required mouldiny
contour.
The present invention overcomes the difficulties
of the prior art described above and provides a method
of manufacturing substantially flawless premium length
mouldings from moulding rips Aaviny portions containing
a flaw which is unacceptable in a clear grade moulding.
According to one aspect of the present invention
there i5 provided a method of converting a longitudinally
elon~ated moulding rip having a portion containing a
flaw such as a knot which is unacceptable in clear grade
mouldings, into a substantially flawless premium length
mouldincl, the rip having first and second flawless portions
of substantially matching grain and a length less than a
premium length, on either side of the portion containing
the flaw, comprising tlle steps of; cutting said rip trans-
versely of its longitudinally elon~ated extent at both ends
of the portion containing theflaw to provide smooth
complPmentary ~irst and second scarf joint faces on the
ends of the first and second flawless portions respectively
disposed adjacent the portion containing the flaw, removing
` the portion containing the flaw from between said first
and second scarf joint faces, bonding said first and
second scarf joint faces d said first and second flawless
portions to one another to form a scarf joint connecting
said irst and second flawless portions to form a rip
havin~ a premi-u~l length, wor~ing the rip to produce a
profiled moulding having a substantially flawless clear
grade surface finish.
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The invention will be more clearly understood ~-
after reference to the following detailed specification
read in conjunction with ~le drawings wherein;
Figure 1 is a pictorial view of a longitudinally
elon~ated moulding rip in which flaws are present;
Figure 2 is a plan view of a portion of tne rip
of Figure 1 after ~le removal of the portion containing
the flaw;
Figure 3 is a side view of the rip of Figure
1;
Figure 4 is a pictorial view of the first and
second flawless portions arranyed with the scarf joint
faces disposed in abutting relationship;
Figure 5 i5 a pictorial view of a finished
moulding :Eormed from the rip of Figure l;
Figure 6 is a pictorial view of an apparatus ..
for use in positioning the scarf joint faces OL the ends
of adjacent flawless portions in an ~uttin~ relationship
and forming a ~ond therebetween,
With raference to Figure 1 of the drawings, the
reference numeral 10 refers generally to a longitudinally
elongated moulding rip. Moulding rip 10 has two portions
containing flaws which are identified by the reference
numeral 14 and three flawless portions 12a, 12b and 12c.
The flaw in the portions 14 may ~e in the form of a knot
or a surface damage of the type which would make it
impossible to conver.t the rip into a premium length
moulding. To be acceptable for conversion by the method
of the present invelltion, the length Ll must be greater
than the premium length, which is generally about seven feet,
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by an amount equal to tne sum of the length L2 and L3 which
must be removed in order to remove the portions 1~.
~ lavin~ determined that a sufficient len~th may
remain after the removal of the portions containing the
flaw, the rip is then cut on either side of the flaw to
form s~ooth complementary first and second scarf joint
faces 18 and 20. Preferably the scarf joint aces 18 and
20 are angularly inclined to the width of ~e rip at
an angle O~ of about 45 and through the thic~ness of
the rip at an angle ~ of about 45.
~n adhesive is then applied to one or both of
the scarf joint faces 18 and 20 o adjacent flawless portions
12a and 12b or of adjacent flawless portions 12b and 12c.
e flawless portions 12a are preferably connected to
the flawless portions 12b rather than to the flawless
portions 12c so that there is a minimum disrruption
in the natural grain pattern of the wood at each joint.
This is im~ortant because of the desire to provide
mouldin~s of a clear grade.
The portions 12a and 12b are positioned as
illustrated in Fig. 4 of the drawings with the scarf faces
18 and 20 in abutting relationship. As will be described
hereinafter the machine used to form the bond provides
clamping forces in the direction of the arrows 22, 24 and
' 26 which serve to maintain a pressure a-t the interface
; until the ~ond ~ormed therebetween is set~ It has been
found ~lat with present technology a satisfactory bond
can be obtained in a very short period of time hence
by the use of a hi~h frequency gluing technique. A
suitable adhesive for use in forming the required bond is
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available from Borden Chemicals, Division of Borden Inc.,
and identified by the trade marks CASCO-P~SI.~ 5~1, CASCO-~ESI-
~595, CASC~IIT~ 12 and I~ONDER BO'~ !B-90~.
The flawless portions 12b and 12c are bonded
to one ano~ler in the manner previously described with
respect to flawless portions l a and 12b.
Tile rip thus formed will have a lengtn which
is at least equal to the required "premium lensth" of
the moulding to be produced ~erefrom. Tlle xip is then
worked in conventiO ~ mould ~rming machinery to the required
contour. Because ~e joints previously forr,~ed in the
rip are scarf joints the only evidence of the joint which
is visible at the surface of the moulding is a simple hair
line 21 which will extend obliquely across t:he finished face
in attrusive straight line. It will be noted that one
attempt has been made to illustrate the normal grain pattern
of a wood moulding in Figure 5 with the result that the
hair line 21 is much more conspicuous in tllis illustration
than it is in a wood moulding h~ving a normal wood grain
finish. It has been found that tne joint produced in this
manner is totally acceptable in most mouldings as being
less of a disruption in the face of the moulding that
natural imperfections and variations in grain C}laracter
o mouldings.
It has been found that clear grade mouldings
can be produced by the moulding of the present invention
in a wide variety of woods commonly used in clear grade
quality includin~ mahogony, walnut, oak and the li]ce and
it may also be used in ~he less expensive woods such as '
30. pine, spruce, fir ~nd hemlock.
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In Figure 6 of tlle dra~7ings, the re~rence
numeral 30 refers generally to a machine for positionin~
the sash joint faces in an abuttina relationship in order
to Pffect gluin~ thereof. The machine includes a stationary
table 3 on wllich a platform 34 is mounted to reciprocate
in the direction oE the arrows ~,. A pair of finger3 3G
are arranged to project upwardly through slots 38 and 40
formed in the platform 34 and table 32 respectively. The
finse~s 36 are mounted to be reciprocally driven in the
direction of the arrows B toward and away from a back stop
plate 40. ~ pair of pressure pads 42 are positioned
above the~ ta~le 32 and platform 34 respectively and are
mounted on reci~rocating drive units 44 so a-. to be recipro-
cally driven toward and away from the table 32 and platform
34 respectively in the direction of the arrow C. A high
frequency glue head 46 is lacated above the platform 34
so as to dlrect high frequency energy to the scæf joint in
use.
In use, a flawless length 12b may be located
on the table 32 and a fla~less length l~a may be located
on the platform 34 with their scarf joint faces 18 and
20 positioned adjacent one another, preferably in a
simple abutting relationship. The various cla7,nping
necllanisms are then activated to engage the flawless
portions 12a and 12b and to move them toward one another
to firmly clamp the scarf faces 18 and 20 against one
anotller. The high frequency gluing machine is then
activated to form the required bond. Thereafter the rip
is removed and a further joint made at the second set ~ ;
of sash joint faces.
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:~; From the foregoing it will be apparent that
the present invention provides a simple and efficient
metilod of convertin~ a longitudinally elonqated mouldins
rip havin~ a ~ortion contai.ning a flaw into a flawless
premium lengtil mouldins.
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