Works On My Bench
Project

DIY Dethatcher Attachment for a Rear-Tine Tiller

How I built a DIY dethatcher for my rear-tine tiller from steel tube and spring steel wire, and pulled 2.5 cubic yards of moss out of my lawns.

Looking down over the tiller handles at the tiller on a lawn, with spring steel tines and a small wheel on each side of the red hood

The problem

I had super heavy moss in the yard and wanted it out before overseeding with a grass and Microclover mix.

I could have rented a dethatcher, but with the hassle of needing a truck/trailer and having to rush against the clock to get it back I figured I could build my own. I already had a rear-tine tiller, a Troy-Bilt Super Bronco CRT that could provide the power. Also, it looked like a fun project!

What I built

The tiller parked on a lawn with the dethatching tines and a small wheel on the side of the red hood, and strips of pulled-up moss and dead grass on the ground around it

A set of dethatching tines that replaces the tiller’s tilling tines. There’s one unit for each side of the tiller. Each slides over the axle shaft and is held by a cross bolt, the same way the tilling tines are.

Each unit is a pair of nested steel tubes with 3/16 in music wire (spring steel) running through matching holes in both. A 10 in Harbor Freight wheel on the outer end holds the tines up so they can’t dig in.

Swapping between the two means undoing the bolt on each side, pulling the tilling tines off, putting these on, and unbolting the reverse stop arm.

The build is split into three parts:

  1. Design in CAD: the tube-in-tube clamp that holds the tines.
  2. The build: a printed jig with hardened drill bushings, then welding.
  3. In action: a grid of passes, and 2.5 cubic yards of moss.

How it works

The main idea is how the wires stay in. The holes in the inner and outer tubes line up, so the wires slide straight through both. A bolt in the far end of the outer tube then pushes on the inner tube, which puts tension on every tine at once and holds it in place. That same bolt carries the support wheel.

The wheels matter because the tiller’s tines are counter-rotating. Without them, the tines dug in.

What didn’t work

Tines and tree roots. Away from the trees the tines mostly held up fine, with no major bends. Once I got under the maple trees, big roots hiding just under the surface caused major bends in a number of them. Slipping a pipe over a tine for leverage bent them readily back into place, so it was an easy fix.

I also ran it without wheels at first, and had to keep the back of the tiller lifted up to stop the tines digging in. Adding the wheels fixed that.

Cost

Part Source Price
1 1/4 in OD x 0.12 in wall DOM tube, 36 in Online Metals $45.48
3/4 in OD x 0.109 in wall DOM tube, 36 in Online Metals $13.54
Shipping and tax on the tube Online Metals $20.11
3/16 in x 36 in music wire, 2 packs of 4 K&S Metals $29.98
10 in solid rubber wheels, 2 at $7.99 Harbor Freight $15.98
7/32 in drill bushings, 3 Zoro $23.98
7/32 in drill bits, 3 Zoro $7.80
3/32 in 6013 welding rod, 1 lb Zoro $9.91
Tax on the Zoro parts, approximate Zoro $3.93
Total about $170

Files & links

Parts

  1. Design in CAD

    Nested steel tubes with matching holes and a clamping bolt: how one bolt holds every spring steel tine in place and carries the support wheel.

  2. The Build

    Tacking the tubes together, drilling the hole pattern with hardened bushings in a 3D-printed block, then welding the end caps and nut for the clamp.

  3. In Action on a Mossy Lawn

    Two passes in a grid, mowing up after each, for about 2.5 cubic yards of moss and grass bits, and what the tree roots did to the tines.