The crankpins leverage M0.6 bolts, with nuts buried in housings inside the back of the wheel. Those nuts are really tiny – 1 mm across the flats, and so, I had always thought I would glue them into the back of the crankpins, rather than risk having them work loose and disappear amongst the ballast. The only question was how? This weekend was the pitched … Continue reading Crankpin nuts: a war of attrition
All I wanted was two holes. Two holes for crankpins 1mm in diameter and the right distance from the centre holes in the quartering jig. It seemed simple enough when I conceived of them. But then, how to get the holes the right distance from the centre? So I made a tiny bushing to fit into the hole in the crankpin jig. Okay, that was … Continue reading Just two holes!
I couldn’t think of any reason to keep the frame pan underneath the frame now that the bearing guides are in place. So, I took the jewellers saw and hacked it away. Now the frame begins to look like a locomotive frame. Inspired, I ferreted out the 3D printed ash pan and tested it for fit. Despite having accidentally sawn off most of the nubs … Continue reading Ash pan test fit
Between the extra-long jig axles and some clamping tabs that I etched into the frame pan, installation of the bearing guides was a walk in the park. I had been a little concerned that the jig axles would be a loose fit on the bearings. As it turned out they were a little snug, and I even had to sand one down a hair to … Continue reading Bearing guides installed
At least I think they should be called jig axles. These pieces of Aluminum rod are used with the coupling rods to ensure the bearings are exactly the right distance apart. Essentially, I will pass these rods through the bearings, fix the coupling rods to the outsides, and then solder the bearing guides to the frame. This allows for a frame that isn’t 100% square … Continue reading Extra-long jig axles
This weekend I formed the crankpins. They are turned from brass as I found, when turning the prototype, I couldn’t drill a long 0.6 mm hole in steel. I made them slightly over-length so I can trim them after I see how thick the rods really are. The real trick was the washers. These are only 1/16 inch (1.6 mm) in diameter, with that same … Continue reading Crankpins for 622
Something has been bothering me. I spent a lot of effort to get the hole in the drivers concentric with the tyre, but then who knows what happens when the axle passes through that hole? Indeed, I’m fairly certain the axles are neither concentric nor perpendicular to the tyre. So, as I have to make two more drivers anyway, I thought I would see if … Continue reading Surprising failure in wheel experiment