Note: Descriptions are shown in the official language in which they were submitted.
CA 02376578 2007-01-17
1 ADJUSTABLE LENGTH HANDLE FOR FLAT FINISHERS
2
3 BACKGROUND OF THE INVENTION
4 FIELD: The subject invention is in the field of extendable/retractable
apparatus
such as tent poles, fishing rods and boat hooks which can be set at any length
within a
6 length range. More specifically it is in the field of such apparatus which
incorporates
7 mechanism by which one mechanism at one end of the apparatus operates and
controls
8 another mechanism at the other end of the apparatus. Still more specifically
it is in the field
9 of such apparatus and related mechanisms adapted for use with apparatus used
in
construction of dry walls in buildings, apparatus known in the trade as a flat
finishing box,
11 used in the crowning and finishing of taped joints between drywall panels.
12 PRIOR ART: Known prior art is shown in the United States patents listed
13 below. These patents are:
14 2,934,937 4,592,797
3,105,262 5,088,147
16 3,146,481 5,099,539
17 3,090,984
18 In the field of drywall construction and finishing, apparatus termed a flat
finishing
19 box is attached to a handle to enable the operator to apply the box to the
joints being
serviced by the box. To adapt the apparatus to various use situations various
lengths of
21 handles are needed to work with, for example, a variety of heights of
ceilings and, also, the
22 box must be set in a range of angles with respect to the long axis of the
handle. The
23 conventional apparatus comprises a fixed length handle with a lever at one
end operable to
24 lock the box pivoted at the other end of the handle at a specific angle in
a range of angles
to the handle axis. When a variety of lengths of handles is required, it is
necessary either to
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CA 02376578 2007-01-17
1 have a number of flat finishing boxes, each attached to a specific length
handle or to use
2 fewer boxes than handle lengths required, (usually one box) and interchange
the box or
3 boxes from handle to handle in order to have the box on a handle of suitable
length. The
4 use of multiple boxes, each with a different length handle attached, is not
generally
acceptable because of the cost and because the compound used in the boxes sets
up, i.e.
6 hardens, so that compound in boxes not fully emptied in use is wasted and
removal of the
7 wasted compound is time consuming. The use of fewer boxes than handles is
standard
8 practice but changing the boxes from handle to handle is time consuming and
tends to be
9 awkward if the box contains the compound referred to in the trade as "mud".
Therefore, for flat finishing drywall joints more efficiently in terms of the
interrelated
11 factors of time and cost, there has been a need for a flat finishing tool
with an adjustable
12 length handle, particularly one adjustable to specific lengths in a range
of lengths.
13 U.S. Patent 5,099,539 (Forrester), U.S. Patent 5,088,147 (MacMillan, the
inventor of
14 the subject invention) U.S. Pat. No. 6,260,238 (MacMillan) and U.S. Pat.
No.
6,412,138 (MacMillan) all show adjustable length
16 handles for flat finishers. All of these handles have a lever pivoted at
one end and a part
17 called a box footplate pivoted at the other. In use a flat finishing box is
attached to the
18 footplate, the handle is adjusted to the needed length and the handle is
maneuvered to
19 place the box against the work surface. This placement sets the box and box
footplate at
an angle to the long axis of the handle and the lever is operated to lock the
box and box
21 footplate at that angle relative to the handle. The mechanical complexity
of these prior art
22 adjustable length handles for flat finishers is typical in the prior art
and increases first and
23 maintenance costs of the handles and degrades their reliability, thereby
increasing
24 operation costs. The lock mechanism in particular tends to be delicate
relative to its
performance requirements and the range of angular motion of the box footplate
is quite
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1 limited. The handle of U.S. Patent Application, Serial Number 091414,677 is
considered to
2 be the least complicated and most rugged of the three prior art handles.
Nevertheless,
3 there is a continued need for more ruggedness and simplicity, to reduce
first, use and
4 maintenance costs.
Accordingly, the primary objective of the subject invention is to provide a
less
6 complicated adjustable length handle for flat finishers because of the
significant savings in
7 costs that the reduced complication facilitates. Other objectives are that
the range of
8 angular motion of the box footplate be relatively large, that there be no
highly loaded small
9 parts, that the handle be relatively lightweight and that it be
ergonomically acceptable.
11 SUMMARY OF THE INVENTION
12 The subject invention is an adjustable length handle for flat finishers.
The primary
13 structural components of the handle are two telescopic tubes. Relative
rotation of the
14 engaged tubes is prevented by engagement of a longitudinal rib on the
outside of one tube
with a groove in a fitting on the other tube. When the tubes are
telescopically engaged
16 each has an overlapped end and a free end. A fitting termed a box footplate
is pivotally
17 attached to a second fitting attached to the free end of the larger, outer
tube, with a pivot
18 axis perpendicular to the long axis of the tubes. The rotation of the
footplate with respect to
19 the long axis of the tubes is controlled by a connecting link which
connects the footplate to
a tube which is slidably mounted in the handle with its axis parallel to the
axis of the handle.
21 A lever pivoted at the free end of the smaller tube is linked to a clamp
mechanism anchored
22 in the overlapped end of the smaller tube. The tube linked to the footplate
extends through
23 and is supported by the clamp mechanism. Operations of the level clamps the
linked tube,
24 preventing it from linear motion and thus preventing rotation of the
footplate relative to the
handle.
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1 The clamp mechanism comprises three parts: a base, a clamp and a clamp
2 actuator. The base is attached inside the overlapped end of the smaller
tube. The clamp is
3 installed in the base and fastened in it so that it cannot move endwise.
There is a hole
4 endwise through the clamp for tube which is linked to the footplate and a
slit from the hole
to the upper face of the clamp. Pressure to narrow the slit clamps the tube.
Pressure is
6 applied by longitudinal motion of the clamp actuator. A cam follower roller
on the clamp
7 engages a slanted slot in the actuator so that longitudinal motion of the
actuator causes
8 lateral motion of the cam follower and the portion of the clamp it's
attached to.
9 The invention is described in more detail below with reference to the
attached
drawings.
11
12 BRIEF DESCRIPTION OF THE DRAWINGS
13 FIG. 1 is a general view of the subject handle.
14 FIG. 2 is an enlarged view of the box footplate pivoted to a footplate
fitting attached
to the free end of the outer tube of the handle.
16 FIG. 3 illustrates the range of angular movement of the footplate.
17 FIG. 4 is a sectioned and cutaway view of the handie taken at 4-4 in FIG.
1.
18 FIG. 5 illustrates the clamp mechanism.
19 FIG. 6 is an exploded view of the clamp mechanism.
FIG. 7 illustrates the clamp mechanism operation lever.
21 FIG. 8 is a view of the handle length adjustment mechanism taken from below
and
22 to one side of the handle.
23
24
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1 DETAILED DESCRIPTION OF THE INVENTION
2 The subject invention is an adjustable length handle for flat finishers, one
3 embodiment of the invention being shown in FIG. 1. Handle 10 comprises two
telescopic
4 tubes 11 and 12 having a common longitudinal axis. Tube 12 is an extrusion,
described in
more detail below and telescopes into tube 11. Tube 11 is termed the larger
tube and tube
6 12 the smaller tube. The ends of the tubes which telescope are termed the
overlapped
7 ends, end 13 of tube 11 and end 14 of tube 12. The other ends of the tubes
are termed
8 free ends, end 15 of tube 11 and 16 of tube 12. In use a flat finisher (not
shown) is
9 attached to box footplate 17. The footplate is pivotally connected to
footplate fitting 18 by
shaft 19. Rotation of the footplate is restricted by link 20, pivotally
connected to the
11 footplate by pin 21 and to fitting 22 by pin 23. Fitting 22 is attached to
end 24 (FIG. 2) of
12 lock tube 25. The longitudinal axis of a longitudinally sliding member,
lock tube 25, is
13 parallel to the longitudinal axis of the handle tubes. Tube 25 is supported
by and slides in
14 hole 26 in fitting 18 (FIG. 2) and a clamp mechanism described below. In
use the flat
finisher attached to the footplate is placed against a work surface, setting
the footplate at a
16 use angle to the handle. The footplate is then locked at that angle by
operation of the
17 clamp mechanism by the clamp mechanism operating assembly 26A, using lever
27
18 pivoted by pin 28 to operating assembly fitting 29 attached to end 16 of
tube 12. Handle
19 length lock mechanism 30 is attached to end 13 of tube 11. Lifting lever 31
releases the
lock so that the length of the handle can be adjusted. Releasing the lever
allows the lock to
21 reset, fixing the length of the handle. The lock mechanism is described in
detail below.
22 FIG. 2 illustrates that there is at least 90 of freedom of the footplate
on the handle.
23 The footplate is shown in solid lines at one extreme of its motion and in
phantom lines at
24 the other extreme.
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1 FIG. 3 is an enlarged view of the footplate, the fitting to which it is
pivoted, the link,
2 the tube end fitting, and the control tube, numbered as in FIGS. 1 and 2.
3 FIG. 4 is a sectional view taken at 4-4 in FIG. 1. Tube 25 is shown
extending
4 through clamp 32 of the ciamp mechanism 33 in end 14 of tube 12. Fitting 34
of the lock
mechanism is attached to end 13 of tube 11 and lever 31 is pivoted to it by
screws 35 and
6 35'. Cam 36 of the clamp mechanism is pivotally connected to fitting 37 by
pin 38. Rod 39
7 is screwed into fitting 37 and is supported at its head end 40 in rod
fitting 41. Fitting 41 is
8 pivotally connected to arm 42 of lever 27 by pin 42'. Moving handle 43 of
lever 27 in the
9 direction shown by arrow A applies a pulling force on rod 39, moving cam 36
to operate the
clamp and prevent longitudinal motion of tube 25 and rotation of the
footplate.
11 FIG. 5 illustrates the clamp mechanism. Clamp 32 is installed in base 44
and held
12 in place by fastener in holes 45 and 46 (FIG. 6) in the clamp and holes 47
and 48 in the
13 base. The mechanism is restrained longitudinally in tube 12 by pin 49 which
is a press fit in
14 hole 50 and extends through the wall of tube 12 and is flush with the outer
surface of the
tube. Cam slot 51 in cam 36 engages roller follower 51' attached to side 52 of
the clamp.
16 Pulling on rod 39 forces side 52 of the clamp toward side 53, locking tube
25 in place
17 longitudinally.
18 FIG. 6 is an exploded view of the clamp mechanism with parts numbered as in
FIG.
19 5. Flanges 54 and 55 of the cam slide in grooves 56 and 57 in the base.
FIG. 7 illustrates the clamp mechanism operating assembly including the
21 mechanism operation lever 43 and its connection to rod 39 with parts
numbered as in FIGS.
22 1 and 4. Pin 28 is carried in extensions 58 and 59 of fitting 29.
23 FIG. 8 illustrates the length lock mechanism 30 in more detail and is a
view taken
24 from below and to one side of the lock mechanism. Lock lever assembly 60
comprises
lever 31, rocker 61 and pin 62 carried in holes 63 and 64. The handle length
is locked
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1 when pin 62 engages one of a series of notches, notch 65 being typical, in
rib 66 of tube
2 12. The rib engages notch 67 in fitting 34 to prevent relative rotation of
tubes 11 and 12.
3 Coil torsion spring 68 urges engagement of pin 62 in the notches.
4 Setscrew 69 (FIG. 7) locks rod 39 and fitting 41 together longitudinally and
rotationally. When the setscrew is loosened rod 39 can be rotated to adjust
its engagement
6 with fitting 37. This adjustment adjusts the angle of lever 43 with the axis
of the handle.
7 The adjustment is set by tightening the setscrew.
8 It is considered to be understandable from this description that the subject
invention
9 meets it objectives. It provides a relatively simple adjustable length
handle for flat finishes.
The range of angular motion of the box footplate is relatively large. The
mechanism is
11 robust and easily adjustable. Also, the handle is relatively lightweight
and ergonomically
12 acceptable.
13 It is also considered to be understood that while certain embodiments of
the
14 invention are disclosed, other embodiments and modification so those
disclosed are
possible within the scope of the invention which is limited only by the
attached claims.
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