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T&D > Programs Areas > Inventory & Monitoring > Aquatic Rake Program Areas
Rake for Aquatic Vegetation Sampling
Rey Farve, Project Leader

Design

The aquatic rake designs presented are intended to illustrate two possible extremes in rake head designs so that a user might use this (or a similar) design to meet their specific needs. A commercially-available, sturdy, light weight and expandable pole was selected.

The rake was designed and manufactured by Joe Fleming of SDTDC.

Rake Pole

The pole is a product manufactured by Unger Window Cleaning Products, which specializes in manufacturing professional cleaning tools.

For the aquatic rake, the 5-section collapsible, telescopic, Unger "Tele--Plus--30-foot" pole was modified. The Tele-Plus pole's original 6 ft sections were cut (using a pipe cutter) to 3 ft sections each. When combined, the 5 interlocking poles can be extended (like a telescope) to a length of 11 ft.

drawing showing a pipe cutter
Pipe Cutter

The "off-the shelf" poles, obviously, could be cut to any length.

rake pole collapsed

rake poles unassembled
Rake Pole - collapsed (top) and separated (bottom)

Rake Head

Standard rake head. The standard rake head was designed to have the dimensions of a standard garden rake. It is essentially a 3/16 in. thick, 9 1/4 " x 5" aluminum plate that was machined into a two-sided rake head.

aquatic rake head - standard
Standard Rake Head. Note the 1/16 in. cable wire that runs through the T-bar opening.

A 9 1/4" x 5" aluminum plate was machined to have rake teeth about 1" in length and be 1" apart. (See photos below.) Four 5/16 in. holes were drilled in the plate to accommodate 1/4 inch U-bolts, which were used to attach the manufactured rake to an Unger "T-bar" attachment (see Unger Strip Washer T-bar). (Note: the Unger Ergo Tec® Locking Cone attaches the T-bar to the pole.)

A 3 foot long, 1/16 inch stranded stainless-steel cable wire is attached to T-bar and strung through the hollow rake poles and attached to a standard dog leach. This allows the user to retrieve the rake head should it become detached from the pole.

standard rake head - top view

standard rake head - top view - close up

standard rake head - bottom view

standard rake head - side view
Rake head - top view (top two); bottom and side view (bottom two)

Comb rake head. The comb rake head is designed to allow the user to sample small-leaved aquatic vegetation (e.g., duckweed). Two designs are presented: one design with the comb "in-line" with the rake pole (photo below, left) and one design with the comb perpendicular to the rake pole (photo below, right).

The comb is a standard, inexpensive 6 1/4 " long comb readily available from Walmart, Walgreens or Target.

in-line alignment
comb rake - perpendicular to pole alignment
Comb Rake Heads - "in-line" alignment (top) and perpendicular alignment (bottom).

The "in-line" comb rake alignment simply bonds a comb into a notch cut into one of the standard Unger attachments. (See Unger Cone Adapter) using J-B Weld® or similar epoxy.

The design for the bracket to hold the comb in the perpendicular alignment is shown in the drawing below.

The comb is held in a transverse-mounted bracket. A 3/4" wide x 6.5" long strip holds the comb in place with two 1/4" screws spaced 4.5" apart.

Two holes are drilled through the comb handle where the screws pass through. (Note a center drill #3 works best to prevent comb breakage when drilling holes.)

The bracket is mounted to a T-bar (cut to a length of 6.5" on top) like the standard rake head.

engineer drawing of bracket design
Design for transverse mounted bracket for the perpendicular alignment comb head.

comb attachment - front view - w/o comb
Brackets attached to T-bar w/o comb (front view)

comb attachment - side view - w/o comb
Brackets attached to T-bar w/o comb (side view)

comb attachment - with comb - bottom view
Comb in bracket: bottom view

comb attachment - with comb - top view
Comb in bracket: top view

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