I built this out of mostly trash. The wood all came from concrete form boards. The plastic tote was something my neighbor threw away for city wide cleanup and the bike wheels came from a bike thrown away from a different neighbor.
I have about $25 dollars total in this project. It may be hard to find all this stuff for free but the 2x4s are not too expensive and I'm sure the bike could be found used or in the trash. I don't know if people throw away these totes often or sell them used but I think a quick Craigslist check will find you something. I know used 50 gallon plastic drums are easily availible and this project could easily be changed to use those instead.
Step 1: Build Wood Frame
The bottom frame consisted of a box with two extra cross members. All my measurements came off the tote NY laying the wood next to it and marking with a pencil. With the rounded edges of the tote and it being very bent up and out of square just marking a length and building it square was easier than measuring with a tape.
The tote is roughly 44 x 59 inches. A pallet may work great for a bottom frame that may be easier than building one.
Step 2: Vertical Members
To dump the cart I plan to just tip it upside down. I made the rear vertical piece about 10 inches taller than the edge of the tote to allow for grass clippings to fall out easily. I bought some wheels from harbor freight to put on the top so that when upside down I can roll it to clear all the clippings. In theory this sounds great but as of yet it is untested.
There is also a rear bumper designed to create a rocking motion to make tipping upside down easier.
Step 3: Bicycle Wheels
For starters the thread pitch on this bike was unmatchable at my local hardware store. Not any flavor of fine/coarse threaded standard or metric seemed to fit right. I planned to just use a long full threaded bolt as an axle. An important thing to know about wheel bearings on a bike is that they are a held in place by a special machined nut. (see photo note) If the special nut only threads onto the original axle stud then the only way I could (quickly, easily, and cheaply) use the bike wheels was to use only the original hardware.
I wanted new hardware because the original axle was too short to span through two 2x4s. To solve this problem I switched 2x4 lumber with 1"x3/16" steel bar. I bolted the steel to the 2x4 frame and drilled out a large recess behind the axle to fit the nut and a socket in the 2x4.
Bike wheels are designed to be supported on both sides. To accomodate this I used a longer peices of the 1"x3/16" bar ran vertically to the top wood framing.
This two sided design should be as strong as it was on the bicycle. The bike could hold 250 plus pounds (my big butt) so I expect the trailer should be able to gross 250 plus pounds as well. The empty weight of the trailer is around 100 pounds I guess so I should be able to pack in over 100 pounds of clippings. I hope to be able to mow both yards twice before having to empty the cart.
One other thing I learned about bike mechanics is removing the gears off the rear wheel. I did some utube research and found that there is a threaded lock ring holding the gears on most bikes. This cheap bike may or may not have had this. I couldn't get it without the special tool which is a spline drive socket and a chain whip to keep the gears from spinning. For a cheap project I wasn't going to spend money on special tools so I just used my angle grinder with a cut off disk and removed the gears that way. Make sure to clean the metal shaving out of the bearing if you follow my lead and chop off stuff.
It was cool to learn and I tried the utube trucks but ultimately for my project/patience I went quick and dirty instead of proper. Job finished is still job finished though.
Step 4: Trailer Hitch
Then on the other end I welded 2"x1/4" plate with two holes drilled into it to bolt to the wood bottom frame.
I made the hitch tounge 6ft long to use as leverage for tipping the trailer upside down. It maybe a little too long but I can always trim it down later.
This hitch is designed to hook to a receiver hitch that only has a hole not a ball hitch. The only hitch I have is a cheap harbor freight that has the ball welded to it. Instead of paying 20 bucks for a hitch with a hole in it I bought 1 foot of 2x2 inch square tubing and used the 2x1/4" plate to build my own hitch that fits in a standard receiver (that's what my four wheeler has) for around $7.00. Most lawnmowers and many four wheeler don't need a receiver to make this work.
Please don't judge my ugly welds too hard. I am way out of practice. I only weld for about 20 mins twice a year until this came up.
EDIT...I added to peices of 3/4 x 1/8 angle iron in a triangular support to the hitch tounge. The angle iron starts back near where the wheels mount and goes 2/3 of the way up the tounge. This really stiffens the hitch and helps to better distribute the weight on the frame to the coupler.
Step 5: Final Thoughts
I have a painting project coming up soon so I plan to use the leftover to put a coat of white paint on this trailer to make it last outdoors longer. I will try to update once it's painted. Also I hope to put up a video of it in action as well.
(5-27-17 final note: I created this entirely with my phone and thr android app. Soon when I'm on a real computer I will add tons of photo notes. I am a visual learner and get way more from the photos in general. I will update this note when I get a chance but I want to publish now for anyone needing a spring project.)