Saturday, June 11, 2016

Bicycle Trailer ep. 1 - Basic Frame

At last, I got a chance to work on this post! (what else do you do when you wake up at 2AM and can't sleep?) The work on this trailer is about 2 years old at the time of this writing, so I might not remember the exact details of how I did it, but I did take more than enough pictures to make up for it.  Let's go!

My starting materials for this were a couple of bed frames, some 26" wheels from a bike I destroyed, a scooter steering mechanism, and the castor I bought in my first post.  First of all, 26" wheels are pretty large for a bicycle trailer, so I wanted to make sure the trailer frame wouldn't look stupidly tiny compared to the wheels.  Besides, it's my first trailer, so why not make it the biggest and best?

In the 3D CAD world, the frame looks like this:
Now for reality world:
First, I had to take the rivets out of the bed frames.  I tried setting it up in the milling machine to do it.  Now, I don't normally do stupid stuff on purpose, but I just had to try this. This easily qualifies for the worst milling setup award, especially since I had to stand inside the circumference of the bed frame while doing the machining.

Hey look, it's working!
Okay, so maybe drilling them out by hand was easier...
The completely disassembled bed frame steel.
I machined some dropouts to hold the wheels on.
After de burring.
I wanted the trailer to be symmetrical which meant the axles would have to be the same lengths.  Since the wheels were from a bicycle, the rear axle was longer because of the multi speed gearing.  The next post will cover this.
After cutting and sanding to length, and sanding off the paint, I am ready to weld the two bed frame support pieces. I clamped them to an aluminum block to insure alignment.
Interestingly enough, this does not qualify for worst welding setup, it was actually easier to do this weld standing up for some reason.  Pretty convenient that the bed frame pieces were just the width I needed.
Notching some more angle pieces for the inner rails.
Clamping and weld prep for the inner rails.
Making sure to weld the inside seam.
I machined a spacer to hold the dropouts apart at the correct axle distance while welding the whole thing.

THIS IS A PUBLIC SERVICE ANNOUNCEMENT: USE A SHARP HACKSAW BLADE! - IT MAKES ALL THE DIFFERENCE!!

Believe it or not, all of these blades are brand new, one of my greater garage sale deals.
Yes, let's try the most new-looking yellow Starrett one, but all of these are good blades. Remember, fine teeth for cutting steel, coarse for aluminum.
Back to the action: clamping the dropout assembly for welding.
Yes? we have progress.
We have balance.
Now for welding the front portion of the frame:
Then welding it to the rest of the frame.
I think this part was to show the improvement in weld quality from switching to a smaller electrode which my machine could handle easier.
ugly
better
Done for now? We're just getting started!

Part 2 Part 3 Part 4 Part 5 Part 6 Part 7 Part 8

1 comment:

  1. Thanks for sharing this nice DIY on Bicycle Trailer. This is educational.

    ReplyDelete