Seed Planting Assistive Device Entourage (SPADE)

Designers: Jennifer Chien, Bill Lee, Linda Ye, David Yudovich

Client Coordinator: Gena Brown

Supervising Professor: Larry Bohs

Figure 1. Seed Planting Assistive Device Entourage


Volunteers with disabilities at the Goodwill Industries of Eastern North Carolina (GIENC) Nature Center experience difficulties with hole spacing, hole digging, and delicate seeding functions.  The goal is to implement solutions that will make their routines more accessible, while allowing them to be independent and maintain close interaction with the ground. The Seed Planting Assistive Device Entourage (SPADE) includes 1) a spacing device for hole alignment and positioning, 2) a digging device for fixed diameter and variable depth adjustment, and 3) a seeding device for output of 1-3 small seeds. Ultimately, this system helps volunteers perform tasks with higher accuracy, gain independence, and develop a sense of accomplishment.


SPADE helps alleviate an otherwise tedious and time-consuming planting task for all volunteers and staff at GIENC. The spacer marks the hole with even spacing and alignment for beds of various dimensions.  Staff commented, “It’s a tool that lends itself well to flexibility”.  The digger provides a more ergonomic and easier method to dig holes of consistent depths.  Staff noted that “it will be beneficial to those with visual impairments and also those with special difficulties”.  The seeder quickly and reliably dispenses small seeds directly to the planting hole, and can be operated by people with wide variety of disabilities. Staff commented, “We like the concept of the seeder. It worked with small and large hands alike and felt natural to use.”


Spacer (left side of Figure 1)

The spacer comprises spacing rods, connecting rods, arrow markers, 4” ring spacers, 4” and 2” ring ground markers, spacer quick release pins, connector anchor bolts, and spacer attachment bolts. The spacing rods are made from 4’ long, 1” square aluminum tubing with 9/32’’ holes interspaced at 1’’ intervals. The outermost holes on each rod are 3/8”, accepting 8” long anchor bolts that fix the spacer securely in the ground. The connecting rods are made from 1’ or 2’-long aluminum tubing with 1/4’’ connector holes. The connecting rods attach flexibly to the spacing rods via commercial L, I, and T nylon resin connectors, secured with ¼” diameter quick release pins.  The arrow markers, constructed from Z-shaped aluminum stock, fasten to the spacing rods at the desired intervals using ¼” bolts and wing nuts, marking the location for future seeding holes. The 4’’ ring spacers, constructed from 4” diameter PVC pipe cut into 1” lengths, fasten to the spacing rods using aluminum L-brackets and ¼” bolts. The 4’’ and 2” diameter ring ground markers are 1” tall PVC rings that are inserted into the ground to accommodate non-linear arrangements of desired holes.

Digger (top right of Figure 1)

The digger comprises an end-capped PVC tube and T-handle with adjustable depth indicator. Four diggers are provided to accommodate 1” and 2” holes in both raised and ground-level beds.  The shorter diggers (raised beds) are 20” long, while the longer ones (ground beds) are 40” long.  End caps on the bottoms of each digger prevent soil penetration.  The depth indicators are made of 1/8’’ thick white HDPE plastic cut in the shape of a semi-circle, bolted to metal L-brackets and connected to the digger tubes using quick release pins. The diggers create consistent holes for planting in the soft soil typical at GIENC.

Seeder (Figure 2, right panel)

The seeder is comprised of a dispensing tube, cylinder, lever, torsion spring, and seeder disk. The dispensing tube is a commercial 50 mL polypropylene conical tube with a screw-cap. The cylinder, constructed from ABS plastic using a 3D prototyping printer, fits into the dispensing tube and is held in place by a holding bolt and lever. The cylinder consists of a loading channel where the seeds are placed, a seeder disk channel where different seeder disks are inserted, and a dispensing channel where the seeds dispense. A smaller spring channel parallel and to the right of the dispensing channel holds a 0.4” diameter torsion spring in place. A 0.25” lever channel cut into the side of the cylinder allows a lever (1/4” screw eye) connected to the seeder disk to rotate 100°. The lever translates linear to rotational motion from the user’s thumb or finger on the lever to the seeder disk. The torsion spring returns the seeder disk from the loading position to the neutral or dispensing position.

The seeder disk, also made with the 3D printer from ABS plastic, rotates within the cylinder, held in place by the torsion spring and a flat-head screw. A holding channel is 90° relative to the loading channel. Clockwise rotation of the disk aligns a holding channel within the disk with a corresponding loading hole in the top of the cylinder, loading a small number of seeds into the disk. Counterclockwise rotation of the disk dispenses the seeds. The cost of the components for all the devices is about $400.

Seed Planter 2

Figure 2.Clients using the spacer and digger (left) and seeder (right)

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