I had the need for a larger bike trailer, but little funds, and minimal tools in which to build one. I already owned a bike trailer that was once one of those "kid cart" type trailers that I had taken the cover off and reinforced with various pieces that once held the top cover/roof.
My project in mind was to take a welding cart and make it into another bike trailer, and that's when I decided that instead of making all new hitch parts for the welding cart, I would just combine the two carts into one for a longer trailer that could give me a bit more capacity, with the minimal amount of work necessary.
My main concern when building the trailer was that it would not be too flimsy as to warrant it unusable, yet easy enough to build that I would not have to seek out someone with welding equipment, either.
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Step 1: Carts Galore
The first bike trailer need to be taken apart so as to remove the top portion and make it as skeletal as possible for practical use. After doing that, I took one section of the metal bar that was once the top support and flattened the end of it so as to connect it to the cross beam in the front; I did this for added stability and to also have a bar that ran through the middle for internal structural support.
The original trailer conversion I also added wood to the top of it for a flatter platform.
Step 2: Joined Carts
This is to give you an overlooking view of how the two carts came together. I took these photos after the fact, but you can get the idea if you've looked at any of the other cart building instructables or anything else similar online regarding this subject, as this one is quite straightforward.
The silver colored cart is the original, refurbished children's stroller cart. The angled beam is actually only connected on the original child's cart, which all sits underneath of the red welding cart. Both carts are joined together by 1" U-bolts, with the exception of the solitary silver EMT conduit beam that runs along the left side of the red welding cart, which is also bolted onto the underlying silver cart with a 1/4" galvanized bolt.
Step 3: Bolted Connection
This is a closer view of how I took the EMT conduit and flattened the end so as to bolt it to the original underlying cart. In the lower right of the picture you can also see the same thing that was done with the reinforced bar from the original cart top piece.
Step 4: Further Detail
These photos just clarify a little more the connections made with the U-bolts. Also, you'll notice that the EMT conduit is somewhat "weaved" through the red cart's horizontal pieces so as to increase the integrity of them somewhat. You'll also hopefully be able to see the where the EMT conduit passes over the top section of the red cart (where the cart's handle joins) I flattened it a bit so as to get a flush fit of the conduit over the cart. It kinda just looks like an extra shiny area in the photo, sorry.
Step 5: Finished Cart
The time involved with making this cart was quite nominal. I bought the child's trailer used from craigslist, and I found the welding cart for $25 at a flea market. There is a parts tray that also came with the welding cart, that I omitted from the finished product.
There are few bolts attached, and very little drilling, since the cart is mostly being held together with U-bolts, and seems to be quite stable. It's overall length is just over 5 feet long, and the hitch from the original cart made it even easier to assemble, since I didn't have to make a hitch from scratch. You'll also notice that I attached the welding cart's handle with the curve facing inwards towards the cart; the reason for this was to create a little extra strength for the inside as well as to prevent the bar hanging downward any more than necessary.
I hope that you found this, my first, instructable to be of some use. Using a bike for transport and to move large items with a trailer is a very environmentally responsible choice in our current world situation, as well as it's a great way to get others to notice that it is possible.
I welcome any and all suggestions, critiques, donations of other carts (PLEASE). And thanks for looking
Leave the SUV at home and get out there and ride!