Single Wheeled Bike Trailer

Step 5 Let the Brazing Begin!

After the horizontal supports were cut and fitted, I began the brazing process by brazing the support piece that I didn't taper to the bottom of the frame. In order to increase the surface area and thereby increase the strength of the bond, I flattened out each end of the support (using a vise). (As I said in the previous step, I didn't plan on using this for anything, but it worked out in the end.

Once this was in place, I worked my way down the frame, putting the next horizontal piece in place. (See pictures for the orders in which the support pieces were added.) Once the first "interior" cross beam was in placed, I tapered the angled support bracket so it would fit at a 30 degree angle to the horizontal support. I then put the second horizontal piece on, fit the angled support piece in place and brazed that in place. Once the angled one was done, I brazed the third horizontal support in place.

Other than 8th grade shop, I had never brazed before and you can tell by looking at the joints. The first few I did are butt ugly. The last ones I did, while not commercial quality, are much better. I used MAPP gas (vs. propane) to get a higher temperature and (hopefully) decrease the time it took. I ended up going through ~1.5 bottles of gas. (I took the torch and a few brazing rods with me on our trip in case I needed to make emergency repairs on the trail. It turned out they weren't needed.)

NOTE: Not being an engineer, I have no idea whether an angled support brace is required or not, but I figured I should add it in order to increase the side-to-side strength of the trailer (since it's only a single wheeled trailer). This is also where the bulk of the weight will be when carrying items.

SUB-NOTE: My dad is an engineer though, and he thought it was pretty good idea.

Comments

[k_man93]

would it be possible to avoid all of this and use some other sort of structural support? I know that conduit is probably the most sturdy choice, but I cannot braze it because i do not have immediate access to a torch... any suggestions?

[rangeside]

Hi, sorry to post again. So you had mentioned that you never really brazed before but was able to make it work for you. I'm kinda in the same boat, in that there was a time that I was fairly good at soldering, but its been a few years. I remember playing around with the solder for a week or so before I was able to get a good bond. I was thinking of using JB WELD on this project to get around brazing, but I'm not too sure if it would hold up over time or under any real stress (even assembled) I've read your instructions a couple of times and noticed that you said that you made significant progress on it . This might sound like a foolish question, but would you do try this again( for the 1st time) knowing the time and effort you put into learning how to braze as you went along. ie if I knew it would be this hard/easy, I wouldn't/would do it again? Also, you said you used a grinder to taper the edges of your supports. I'm wondering if you tried a hole-saw bit or even a 1/2 metal drill bit and they didn't work, or if you went this way to cut down on costs? Thanks again.

[samfelis]

Had I known how to braze before I started this project, it would've taken a lot less time, that's for sure. Regardless, I still would've gone through with it due to the costs involved of building one vs. buying new. (Yes, I was taking a chance on the trailer, but I had a backup plan -- a two-wheeled trailer -- if my test rides didn't work out as planned .) I can't see dropping $300+ when I could build my own w/ recycled parts for much cheaper. Going into it I didn't think it would take as long as it did, but I also gave myself a few hours a day to build it over the course of a week. I did try using a hole saw bit, but found the results to be less than desireable. With the grinder, I could get a somewhat perfect match between the two pieces of metal. Once thing I learned during this was that the more the two pieces are in contact w/ each other, the better the result of the braze as I wouldn't have to "fill the gap" with the brazing material. I didn't think about a 1/2" metal drill bit as I don't have a drill press and using my hand drill for that many would probably resulted in a lot of hit and miss. If you have access to a drill press, that might be a better alternative. Don't hesitate to ask if you have further questions. I'm happy to share whatever knowledge I can.

[Calorie]

Be careful when brazing conduit. It is coated with Zinc that makes it corrosion resistant. However, when welding it releases gaseous zinc. Inhaling these fumes creates a temporary sickness that feels like the flu. A welding mask solves the problem. It looks like a paper mask you might wear to block out pollen or dirt. However, this has a zinc filter that absorbs the fumes. I would not weld/braze without one. The masks are cheap, and are far better than throwing up and having flu symptoms for several days.