Broadcasting Grass Seed Spreader

This actually ended up really useful, if grass seed wasn't so expensive I'd be using it all the time because it really works well!

Long story short, I needed to spread some grass seed so I designed and 3D printed one (well mostly printed, there are a few screws, dowels, and airsoft BB's in this one… LOL).

I tried to cut down on the number of parts printed, but it still was a lot, in my opinion anyways. I'll try to summarize the whole thing here, but if you jump on over to YouTube I've made a video in two parts explaining and showing quite a bit more about it.

If you're interested, here they are:

Part 1

Part 2

I was able to print all the parts out on my Creality Ender 3, but some parts may be too large for some of the smaller printers. The largest piece, the ‘Hopper’ measures 3.75" [95.3mm] x 6.25 [158.8mm] x 8.50" [215.9mm], so plan accordingly for your printer.

Supports - Some parts will need supports: Lower Housing, Bearing Housing, & Hopper. I used tree supports for all these. The other parts will not need supports if oriented properly.

Orientations - There are a couple of photos in the project that show all the parts on the print bed in the orientation they were designed for, and that I used. I did not print them all in one go as these build plates are showing, I simply placed them on there for a photo reference.

Material - The choice is yours, I used PLA for all the ones I made because it works well with my machine.

Printed Parts Data (What I Used):

Qty      Name                      Wall Thickness          Infill                         Supports

2          Bearing Cage                2mm                     20% Gyroid                 No

2          Bearing Raceway         2mm                     20% Gyroid                 No

1          Bearing Housing          3mm                    20% Gyroid                 Yes

1          Bevel Gear                    2mm                     20% Gyroid                 No

1          C-Clip (Large)                2mm                     20% Gyroid               No

1          C-Clip (Small)                2mm                     20% Gyroid               No

1          Compound Gear          2mm                     20% Gyroid                 No

1          Drive Shaft                    2mm                     20% Gyroid                 No

1          Handle                           2mm                     20% Gyroid                 No

1          Hopper                          1.2mm                 15% Gyroid                  Yes

1          Lower Housing             2mm                     20% Gyroid                 Yes

1          Metering Wheel           2mm                     20% Gyroid                  No

1          Slinger Wheel               2mm                     20% Gyroid                  No

2          Washer                          2mm                     20% Gyroid                  No

Additional Parts (non-printed):

( 2 pcs ) 3/16" steel dowel - One cut to 1-1/16" and the other cut to 2-3/16" length.

( 16 pcs ) 6mm dia Airsoft BB's

( 11 pcs ) Socket Head Screw, M5 x 8mm length

This model does require cutting threads in holes post printing, you will need an M5x.8 tap.

Additional Info:

There are many aspects to this model which are pretty cool on their own. For instance, the ball bearings, these are so cool I made a couple of other videos completely about them. They require their own form of sub-assembly inside of this grass seed spreader. If you'd like to learn more about them just check out my YT channel.

Another cool part this has included with it is the rotary valve to dispense and meter the seed as it makes its way down from the hopper to the slinger wheel. The gearing was pretty neat on this one too, these were models I downloaded from supplier websites and modified (of course I didn't want to draw them, this model was already getting too involved as it was).

Assembly:

As mentioned above, there are two videos on YouTube where I'm putting this together piece-by-piece. If both videos are unable to be posted to this description, follow the link in the description of the first YT video to get to the second part, or visit my YT channel page to see both parts of this one and all the other videos I've posted of 3D modeling and printing.

Condensed assembly instructions:

1- Assemble the bearings (might want to watch either these videos or the dedicated bearing videos for this part)

2- Place bearings in bearing housing with inner race's lip facing outward on both.

3- Slide the metering wheel into the bearing housing

4- Place the handle on the drive shaft

5- Place the drive shaft into the bearing housing, through the first bearing, through the metering wheel, and out the second bearing.

6- Place bevel gear on end of drive shaft

7- Install C-Clip to end of drive shaft

8- Install C-Clip to drive shaft between handle and first bearing

Bearing housing is complete (A.K.A. Rotary Valve Assembly)

9- Place completed bearing housing onto lower housing, install screws.

10- Install slinger wheel with washer below it, using the 2-3/16" long piece of 3/16" dia dowel

11- Install compound gear with washer below it, using the 1-1/16" long piece of 3/16" dia dowel

Lower Unit Complete

12- Install Hopper to Lower Unit.

Done, Go Spread Some Grass!

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For lots more info, including an assembly walkthrough, background info on the design/inspiration, and to witness the testing performed please watch the videos above in the description.

Thank you for checking it out!

*Update 2-19-26 - Added STEP Files in a compressed format to 'Other Files' for people to mess around with it.