Note: Descriptions are shown in the official language in which they were submitted.
CA 02534512 2006-O1-31
ULTRALIGHT SELF-LEVELING FORM STAKE
DESCRIPTION
Field of the Invention
[Para 1 ] The present invention is in the field of stakes used to support
concrete forms or
barriers that are used along the outside of an area in which concrete is to be
poured, so as
to contain the poured concrete in that area.
Background and Description of Related Art
[Para 2] Concrete form stakes are typically used to secure wooden boards or
"forms"
around the perimeter of a concrete pouring area, the stakes driven partway
into the ground
along the outside face of a form to hold it securely in place before, during,
and after the
pouring operation. Known stakes come in many shapes and sizes, for example
homemade
stakes made from scrap wood at the construction site as well as different
types of
commercial stake made from wood, plastic, and metal.
(Para 3] Another type of stake used in concrete pouring operations is known as
a screed
stake, used in spaced pairs to hold screed rods or bars in an even plane
across the area to
be poured to ensure that the concrete is level and smooth.
[Para 4] My earlier U.S. Patent No. 6,588,164, issued~uly 8, 2003, discloses a
stake
especially adapted for use as a screed stake, but which can also be used as a
form stake.
This screed/form stake has a flat rear face and a U-shaped upper cradle
portion extending
from the front face of the stake, the cradle designed to mate with a separate
driver. The
driver also has a flat rear face, and a screed-rod-shaped portion that extends
from the
front face of the driver to mate with a screed rod groove in the cradle
portion of the stake.
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When the lower end of the driver is mated with the stake's upper cradle, the
upper end of
the driver serves as a pounding surface to drive the stake into the ground.
The upper
surface of the screed-rod-shaped portion of the driver can be used as a screed
rod
elevation-measuring surface when seated in the cradle, providing a platform
for a transit to
measure whether the stake has been pounded in far enough to support a screed
rod at the
proper height. The screed/form stake has holes formed along its face for
securing it to a
concrete form with screws or nails. When used as a form stake, the stake is
driven home
with the same driver used for screeding operations, with the flat back of the
driver allowing
it to be used against the face of the form without interference. As shown in
the patent, the
stake can be driven to a point where its cradle is below the upper surface of
the form. The
stake is typically removed from the exterior face of the form after the
concrete has been
poured and has set.
[Para 5] I have a co-pending U.S. Patent Application No. 10/957,348 filed
October 2, 2004
for a stake designed specifically for use as a form stake. The stake can be
pounded or
driven into the ground with any non-specialized driving tool, such as a hammer
or mallet or
even a boot, and naturally levels itself at the top of the concrete form when
pounded with
such a tool. When the form is no longer needed, the stake can be easily pulled
out of the
ground with fingers or the claw of a hammer or tool. The form stake has a
relatively wide,
flat body with a flat rear face, and a forward-facing T-shaped flange
structure extending
from the front face of the stake. The T-shaped flange structure has a
horizontal driving
shelf with a uniform, level impact surface at the top of the stake, and a
central vertical rib
section extending downwardly from the driving shelf with a depth equal to the
depth of the
shelf protruding beyond the face of the stake. The driving shelf forms the top
surface of
the stake. The vertical rib bisects the stake. In a preferred form, the
underside of the
driving shelf has a predominantly perpendicular or acutely-angled surface on
both sides of
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the central rib for grasping with the fingertips or hooking with a tool to
pull the stake out of
the ground. Although the form stake is lighter and less expensive to
manufacture than my
previous screed/form stake, it is easier and faster and stronger to use as a
form stake.
[Para 6] Perhaps the most common type of concrete form stake is a simple nail
stake,
which looks and functions like a giant nail, except that it typically has a
number of holes
formed along the shank of the nail for securing it to a wooden form board.
[Para 7] Nail type stakes are often used for other purposes, most notably as
tent stakes,
since they easily penetrate even the hardest ground. When used as tent stakes,
nail stakes
are sometimes provided with a cross-piece frictionally held in place on the
upper end of the
shank below the nail-head to provide a pull handle and a place to tie guy-
lines from the
tent.
Brief Summary of the Invention
[Para 8] The present invention is a form stake with a narrow ground-
penetrating shank
terminating at its upper end in a wider, horizontal, integral driving shelf
that allows the
stake to be pounded or driven into the ground with any non-specialized driving
tool, such
as a hammer or mallet or even a boot, and naturally levels itself at the top
of the concrete
form when pounded with such a tool. When the form is no longer needed, the
stake can be
easily pulled out of the ground with fingers or the claw of a hammer or tool.
The driving
shelf has a wide; uniform, level impact surface at the top of the stake, the
preferably
cylindrical ground-penetrating shank extending downwardly from the center of
the driving
shelf and tangentially aligned with a flat, rear, form-abutting edge of the
driving shelf. In a
preferred form, the shank has a diameter or width equal to the front-to-back
depth of the
driving shelf. The outer ends of the driving shelf extend freely beyond and
above the shank
body.
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[Para 9] In a further form of the invention, the underside of the driving
shelf has a pair of
opposing force-transferring flanges extending downwardly and inwardly at an
acute angle
to an upper end of the shank. The flanges are thin-walled and centered on the
underside
of the driving shelf. In a preferred form, the flanges extend from an
intermediate portion of
the underside of the driving shelf, such that the outer ends of the shelf
extend beyond the
uppermost portions of the flanges.
[Para 10] In a further form of the invention, the shank portion of the stake
is cruciform in
section, with the force-transferring flanges merging into two side ribs of the
cruciform
shank.
[Para 1 1 ] The present form stake is lighter and less expensive to
manufacture than my
previous form stake, is easier and faster to use as a form stake, and is less
likely to wander
or cant when driven into hard ground.
Brief Description of the Drawings
[Para 12] Fig. 1 is a perspective view of two form stakes according to the
invention, one
prior to being driven into the ground against a wooden form, and the other
driven in level
with the top of the form.
[Para 1 3] Fig. 2 is a front elevation view of a stake as shown in Fig. 1.
[Para 14] Fig. 3 is a side elevation view of the stake of Fig. 1, partially
driven into the
ground against the outside face of a concrete form.
[Para 1 5] Fig. 4 is a side elevation view similar to Fig. 3, but with the
stake fully driven into
position adjacent the concrete form.
(Para 16] Fig. 5 is a top plan view of the stake of Fig. 4 driven into the
ground against the
face of the form, with the shank portion of the stake shown in hidden lines.
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[Pare 1 7] Fig. 6 is a side elevation view similar to Fig. 3, but shows the
stake being pulled
from its fully driven position by hand.
[Pare 18] Fig. 7 is a perspective view of a stake similar to the stake in
Figs. 1-6, but with a
cruciform shank.
[Pare 19] Fig. 7A is top plan view of the stake of Fig. 7, with the cruciform
shank section
shown in hidden lines.
Detailed Description of the Invention
[Pare 20} Referring first to Figs. 1 and 2, the invention is illustrated in a
first illustrative
example as form stake 10. Stake 10 is preferably molded as one piece from a
suitably
strong plastic material, for example a nylon or ABS plastic, although other
plastics and
materials such as wood or metal can be used, and although the stake is not
limited to one-
piece construction. Stake 10 is used to laterally secure a wooden form 12 in
place around
an area in which concrete 13 is to be poured. As shown in the Figures, stake
10 is driven
into the ground with its rear surface against the outer face of form 1 2 to
prevent the form
from shifting during pouring or curing of the concrete against the opposite
inner face of
form 12. The length of stake 10 can vary from under a foot to several feet in
length, but in
the illustrated embodiment is on the order of twelve to fourteen inches in
length.
[Pare 21] Stake 10 has a cylindrical ground-penetrating shank 16 terminating
at its upper
end in a flat, horizontal driving shelf 1 8 formed as an integral part of the
stake, whether by
molding, welding, mechanical attachment, or some other method for giving the
driving
shelf 18 a permanent, non-rotating, fixed driving connection to shank 16. The
lower end of
shank 16 preferably terminates in a point 16a that helps the shank penetrate
hard ground.
[Pare 22] As best seen in Figs. 2 through 4, driving shelf 18 has a flat top
surface 1 8a, a
flat bottom surface 18b, a rear edge 18c flush at 17 with the tangentially
rear-most portion
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16b of shank 16, and a front edge 18d flush at 1 7 with the tangentially front-
most portion
16c of shank 16. Driving shelf 18 extends beyond both sides of shank 16, in
the illustrated
embodiment having a width (for example, 2.875 inches} at least three times the
diameter
(for example, 0.875 inches) of shank 16. The flat top surface 18a of driving
shelf 18 forms
the upper end of the stake, with a surface area greater than the cross-
sectional area of
shank 16. As best shown in Fig. 5, when stake 10 is viewed from above, the
relatively wide,
flat, upper face 18a of driving shelf 18 is the only visible surface,
overlying the
circumference of shank 16, and therefore presenting a significantly greater
driving face.
Fig. 5 shows the tangential or flush alignment of the rear-most and front-most
vertical
edges or surfaces 16b, 16c of shank 16 with the rear and front edges 1 8c and
18d of the
driving shelf, allowing the form-facing side of stake 10 to present a smooth,
unbroken
sliding face to form 12 as stake 10 is driven into the ground against the form
until the rear
edge 18c of the driving shelf is against the form. While a perfectly smooth,
flat, uniform
upper surface 18a is preferred, it will be understood that minor variations
such as different
textures or surface finishes or patterns that leave the upper surface
generally flat relative to
the driving force and the top of the concrete form are acceptable. It will be
understood that
if both the rear and front edges 16b and 16c of the shank are flush with the
rear and front
driving shelf edges 18c and 18d as shown in Fig. 5, stake 10 can be used
reversibly against
form 1 2.
[Para 23] The junction of the upper end of shank 16 and the lower surface of
driving shelf
18 is reinforced with angled fillets or flanges 20 extending from intermediate
portions of
the underside of the driving shelf to the sides of the upper end of shank 16,
centered on
the underside of the driving shelf 18 in alignment with the long axis of the
shelf. Flanges
20 are preferably molded in one piece with the rest of stake 10. Flanges 20
are also
preferably thin-walled, as illustrated, allowing an essentially tangential
connection to the
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sides of shank 16, and providing room for fingers or a tool to grasp the
underside of shelf
18 in the vicinity of the flanges. Flanges 20 efficiently transfer driving
force from regions of
the driving shelf 1 8 on either side of shank 16 into the shank, reducing
stress at the
junction of shelf and shank, and helping to keep the shank driven straight
down even when
the driving force is off-center.
[Para 24] Referring to Figs. 3 and 4, stake 10 can be pounded into the ground
with any
non-specialized tool, for example the illustrated mallet 30, since the upper
driving surface
i 8a of the stake is a flat, wide, uniform force-distributing surface. No
specialized driving
tool is necessary, and, in soft soil, foot and even hand pressure (with body
weight behind it)
may be used to push against the relatively wide, even surface of the driving
shelf. Driving
the stake with non-specialized tools is accordingly both effective and
comfortable, whether
using a hammer, a mallet, a rock, a board, a boot, a hand, or any other
convenient
implement.
[Para 25] As best shown in Figs. 1 and 4, stake l0 tends to automatically
level itself both
vertically and side-to-side at the upper surface 12a of form 12, since a non-
specialized
driver (especially a driver with a driving or impact face wider than the depth
of shelf 18) will
tend to hit the upper surface 12a of the form when the flat upper surface 18a
of driving
shelf 18 is even with the upper surface of the form. Assuming that the overall
length of
stake 10 allows a sufficient portion of the stake to be driven into the ground
for good
holding power relative to the ground, leaving the stake's upper end 18
approximately even
with the upper edge of form 12 provides the strongest possible support for the
form.
Leaving the upper surface of the stake 10 even with the top of form 12 also
ensures that
concrete smoothing tools can be run across the top of the form without
interference. The
overall jobsite is also given a neater, more professional appearance with all
form stakes
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.driven in evenly against the forms. And the risk of overdriving the form
stake to a point
where it becomes difficult to remove from the ground is reduced or eliminated.
[Para 26] Referring next to Fig. 6, stake 10 is also easily pulled out of the
ground when the
concrete forming operation is done. The lower surface or underside 18b of
driving shelf 18
is preferably perpendicular to the shank 16 of stake 10 so that maximum
pulling force can
be exerted on the stake through the shelf with the fingers or a tool hook or
claw, as shown.
The lower surface 18b can also be angled inwardly at an acute angle to the
front face of
stake 10 (not shown), for an even better hooking action on the shelf when the
stake is being
pulled from the ground. While the lower surface 18b is preferably flat and
uniform as
shown, it is possible to vary the contour so long as significant gripping or
hooking portions
are perpendicular or acute.
[Para 27] Holes 22 through shank 16 allow the stake to be secured to the face
of form 12
in known manner, for example with nails or screws driven through holes 22 into
the face of
the form. Holes 22 preferably pass through shank 16 perpendicular to rear and
front edges
18c and 18d of shelf 18, and therefore perpendicular to a form 12 being
supported by a
driven stake 10. Holes 22 could also be acutely angled, but angles greater
than 45° tend to
put nails or screws inserted through the holes at an ineffective angle
relative to the face of
form 12.
[Para 28] Referring to Fig. 6, although the thin walls of flanges 20 leave
room for fingertips
to hook the underside 18b of shelf 18 on either side of the upper end of shank
16, upper
portions of flanges 20 extend only partway toward outer ends 18e of the shelf,
allowing
fingers or a hooking tool to wrap fully under (and even around the outer ends
of the shelf
18 when the shelf reaches a point higher than form 12) for a better grip, as
shown in
phantom. This gives the person removing stake 10 the ability to exert both a
very strong
vertical pulling force, but also creates a moment arm relative to the shank
body to provide
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side-to-side leverage to rock or loosen the shank to help free the stake from
difficult
ground. This is useful where the stake becomes firmly lodged in the ground,
for example if
a rough shank surface finish or holes 22 attract concrete dust or moist or
compacted dirt or
snow that can cement or freeze the stake into the ground.
[Para 29] Referring next to Figs. 7 and 7A, a modified version of stake 10 is
illustrated at
100, having a cruciform-section shank 1 16, a driving shelf 1 18 essentially
the same as shelf
18 in Figs. 1-6, and force-transferring flanges 120 similar to previously-
described flanges
20. The cruciform shank 1 16, centered under driving shelf 1 18 and having a
narrow,
ground-penetrating body, will generally be lighter than cylindrical shank 16
if made from
the same material, and may have some advantage in penetrating and holding in
certain
types of soil. The diameter of shank 1 16 and its relationship to driving
shelf 1 18 is
preferably similar to that of shank 16 and shelf 18, with the same tangential
alignment of
the rear and front ribs 1 16c and 1 16d with the rear and front edges 1 18c
and 1 18d of
driving shelf 1 18, and the same proportion of shelf width to shank diameter.
The side ribs
1 16e of shank 1 16 lend themselves to being extended to form (or to merge
with) flanges
120 at the upper end of the shank.
[Para 30] It will be understood that while the circular and cruciform shanks
16 and 1 16
illustrated above are currently preferred, other cross-sectional shapes are
possible,
provided that at least the central rear edge or tangent of the shank body
centered relative to
drive shelf 18 is flush or tangential with the center of the rear form-facing
edge 1 8c of shelf
18. It will also be understood that while a rectangular shelf 18 is preferred,
other
symmetrical shapes with a flat rear form-facing edge are possible. And while
the illustrated
embodiments show single front and rear vertical edges or surfaces of the shank
body
aligned with the front and rear edges of the driving shelf 18, it is possible
to align multiple
front and rear edges of surfaces of a shank body with central portions of the
front and rear
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edges of driving shelf 1 8, for example by rotating the cruciform shank body 1
16 of Figs. 7
and 7A approximately 45°.
[Para 31 ] It will be understood that the length and width and relative
dimensions of shank
16 and driving shelf 18 can vary according to the anticipated height of the
forms with which
it will be used, the nature of the ground into which stake 10 will be driven,
and the weight
or force of concrete that is anticipated against the form.
[Para 32] While stake 10 is especially designed for use as a form stake, it
may find use in
other applications for providing good holding power against significant forces
in loose soil
or sand or even snow.
[Para 33] It will be understood that the disclosed embodiment is
representative of a
presently preferred form of the invention, but is intended to be illustrative
rather than
definitive of the invention. The scope of the invention is defined by the
following claims. I
accordingly claim:
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