I'm really stoked on building some bike frames right now, so I'm using my brief downtime between other projects to build a couple.
Preparing to notch the seatstays. I made a new mitering fixture that allows me to notch both stays simultaneously, which may not sound like much of an advantage, but believe me, it results in a much more accurate cut that doesn't look all cattywampus when it's finished.
Above: Using a center finder to eyeball the center of where I want the cut to be.
Another really nice thing about this new stay mitering fixture is that it allows me to notch both ends of the stays without removing them from the fixture, which makes it so much easier to get everything lined up in the same plane. This frame is already going so much better than my last build, and I haven't even started welding it yet.
Fixturing the chainstays in the jig to cut the bottom bracket shell notch and the dropout slots. I adapted the design of this fixture from a guy on youtube who has a channel called "Pithy Bikes" where he has a video series of him building his first bike frame.
Test-fitting the right-side rear dropout in the slots that I cut into the stays. It fits SO MUCH nicer than the last frame I built, where I did a lot of this fitting work by hand with a file. The dropout is a Paragon Machine Works 12mm thru-axle dropout with a flat-mount disc brake interface on the left side.
Something that I've wanted for a long time is a really powerful belt grinder, but the commercially available machines run around $3,000 for the good ones. It could be argued that that is a reasonable price when I factor in the amount of time I spent on this project, but I had a month of relatively little work (a good thing, sometimes), so I banged this thing out. It will run a 2" x 60" belt at 8,000 feet per minute:
Here is a detail of the belt tension and tracking mechanism. The dark green knob preloads the spring that is used to tension the belt. The yellow knob changes the angle of the tracking wheel, which allows the belt tracking to be adjusted side to side.
The grinder in its nascence.
Fixturing the two halves of the contact wheel frame. The cylindrical members are just spacers to hold everything in place while I welded it all together.
The work rest/table. Extra heavy duty!
The contact wheel and work rest installed. All the fasteners shown here are 1/2". Probably overkill, but I wanted it to be super rigid.
Below are shown some new brackets for the Flanger. These will allow two more booms to be attached to the center hub, so that four people total can ride it.
These box tubes are for a piece of rigging for my neighbor who does live sound and light production. Up to a ton of speakers can hang from these frames.
The mess made by drilling a hundred and thirty-six 3/4" holes. Drilling all these holes allowed me to experiment with cutting feeds and speeds. I think I might have smoked my $70 drill bit, but I learned a lot in the process.
So, it's been a while since I've posted up photos, but I got the Flanger done in time for the Open Streets Festival in Corvallis. It was a big hit!
I had to learn how to work with hydraulics in order to hook up the drive pump and motor. The bicycle in the foreground in the last picture has a hydraulic pump on it, driven by the rear wheel. That pushes fluid through a hydraulic hose to the drive motor at the center. As the bikes gain speed, they fling out. Unfortunately, I had the hoses made a little short, so they pull tight when the riders go too fast, but that's easy to fix with longer hoses.
The Flanger took up most of my spare time over the past few months, so I am now back to working on other projects.
Canoe trailer for a friend.
This is the first time I have assembled the Flanger all the way. It was pretty exciting to see it this far along. I swung around on the arm to see how it would handle my weight, and I'm a little unsure about the bending strength of the center post. Might have to head back to the drawing board. Maybe an internal sleeve to stiffen it.
This is a really heavy duty bumper for a little Toyota pickup. It's got a real stout 2" receiver built into it.
My garage right now: three utility trailers, a bike chariot, a coffin cargo bike and 15 bikes depending on the day.
Boring out the bronze bushing to fit over the center post.
The bronze bushing sleeved over the center post.
Machined end cap that the tapered roller bearing sits on.
Welded onto the top of the center post.
Very jankily truing up the ends of the spreader tubes. The lathe is maxed out at 37.5" and I had to use a boring bar to reach the end of the workpiece.
The lower hub assembly tack-welded to the spreader tubes. I had to be really careful to make sure the heat of welding didn't distort anything and cause a bearing to bind.
The upper hub assembly, upside down on my welding table, being tacked onto the spreader tubes. The main bearing sits inside that square piece of plate that's just under the end of the center post.
Finished lower hub assembly with arms attached.
Boring out the hole in the hub of the flanger to fit around the center post of the base. The cylindrical thing on the far right is an oil-impregnated bronze bushing that will bear the radial load of the upper assembly.
I built this liftgate extension flap (in blue) for a freight truck. It folds down flat to form a larger platform.
My roommate giving my other roommate a ride to work in the cargo-coffin.