A little bit of progress on everything
I have nothing finished to show, but I have progress on the deck, cargo bike, and my bicycle jig.
The deck is half done. We were hoping to finish it this weekend but the 90F weather kept us off of the roof. We’re also waiting on 5 more boards to be delivered. The new decking is Tigerwood (from Ecohaus) and I really like how it looks so far. We’re using hidden fasteners called EB-TY. It took us a little while to figure out the best way to build the deck (especially because we are doing it in sections so that it can be disassembled), but now it is going pretty fast. Hopefully we can finish it up next weekend.
I’m embarrassed to show these photos of the cargo bike and fixture in progress because they show how much of a slob I can be about my workspace. The basement is a disaster, but I never feel like stopping work to tidy up.
The CAD drawing has been updated. There are a few changes and I switched the drawing to much easier to work with software (TurboCAD, I was using QCad).
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Real progress on the cargo bike is occuring on two fronts. The first is building tooling that will be used on any frames that I built. I have most of the front triangle fixture completed. I’m building my fixture around a milling table that is 9 inches by 36 inches with 3 T-Slots running the length of the table. This table is accurately machined flat (not as perfectly as a surface plate, but well enough for bicycle frames) so I can also use it as an alignment table.Everything will be modular so that I can use the same base for building forks, rear triangles and other things.
Here is the table setup as a front triangle jig:
The bars under the seat tube and head tube are made from pieces of 80/20. They have T-slots in them too and are connected to the table using some brackets that I made. The brackets connect to the 80/20 usingT-Nuts that 80/20 sells and to the T-Nuts for the milling table. The milling table T-Nuts are setup for 1/2-30 bolts that are huge, but I bought some reducing bushings from McMaster-Carr that let me use smaller bolts. I can adjust them to any angle (using a protractor to check the angle) and then lock them into plate.
The tubing is held in these towers which are also primarily 80/20 with tube holding cones that I made on the lathe. I got the idea for these towers from a bicycle jig on Instructables, but changed the setup to be height adjustable. I shouldn’t need to adjust it once the whole thing is dialed in.
The bottom bracket is held in place with a vertical post and cones which sit on it. This is sort of an exploded view, with the top cone loosened. Everything is clamped in place with two clamping collars.
The other progress is on the cargo bike itself. As you can see in the first photo the donor frame has had it’s paint stripped (where I need to braze to it) and the headtube and downtube have been cut off.
The cargo tube on the cargo bike has some really tricky mitering. I built a fixture to do this miter (and others) on the lathe. This is what the mitering fixture looks like: (I’ll take some photos of it in use next time I’m using it).
It mounts to a T-Slot in the lathe’s compound slide. I can set the angle to on the compound slide to my miter angle and then use a hole saw to make the cuts. That block was made on the lathe and boring a 1.75″ hole took a long time. I’ll be able to use it for other tubing sizes with some reducing bushings that I need tomake. The mitering fixture works really well,but I need to tweak it a bit to get it better centered. Right now the miters are about 1mm off of center.
In that photo you can also see one of my test joints (I’ve made three of these and cut the other two apart). I’m pretty happy with the brass penetration that I’m getting,but the brazing looks a little sloppy and will require cleanup work. I’m getting better with practice, these big joints are a lot different than the little ones that I make for racks.
The joint is neat because the smaller tube completely pierces the larger one. When looking at it from the end you can see light coming around the smaller tube:
Remarkable, Alex. I can”t believe how far your fabrication skills have come in such a short time. I only wish you were in Portland so I could drop by your basement from time to time.
Keep good notes. As you refine this cargo bike design, I can imagine this repurposing of old frames really taking off in the DIY bike community. Maybe this will be the new tall bike–certainly more practical.
Could the machined parts be reproduced through something like emachineshop? I guess that would still leave the mitering work for those without access to a lathe.
Thanks again for writing up these reports.
best,
joe
Joe — There aren”t many machined parts required for the frame conversion. Pretty much everything is for building my frame jig. I was going to try and seperate those two stories (building the frame jig vs building the frame), but right now they are intertwined in the basement so the stories are intertwined as well. I don”t think that a frame jig would be necessary for this project, but I want one for building full bikes too.
The only joint which really benefits from machine mitering is the through hole for the cargo tube. This could probably be done by hand with files and a hand drill, but I wouldn”t want to attempt it.
I agree that repurposing of old frames is a great way to go. When I first got into bicycle related metal working I could think of many more repurposing projects than “build from scratch” ones. It’’s also saving me a decent amount of money and time to use an existing donor bike.
THanks for posting this, Alex. I”m following along, especially for ideas on converting old machine parts into fixture bases.