RazEr rEVolution: Concrete-wheel-be-gone

Continued from last time, I’ve finished installing the 5″ Colson wheels onto RazEr rEVolution.

This was how RazEr was meant to be. Seriously, why didn’t I just start it off with Colsons initially? While it’s still not as smooth over the average sidewalk seam as, say, a pneumatic tire, it is a marked improvement over my surplus forklift tires.

The story continues…

The first order of business after the can was completed was to install the magnets. Foreseeing another potential stray magnet spacer herding episode like the first build of the motor, I went ahead and cheated by 3d-printing a small magnet spacer thing. This must have saved at least an hour or two of diddling with little wooden sticks.

The magnets were first located using rubberized CA glue wicked into the gaps.

Next, I mixed up my favorite concoction of West System 105 epoxy with 109 hardener and a ton of phenolic fluff filler. The filler adds volume and thickness to the epoxy and prevents it from running everywhere.

Make-a-Bot has actually been instrumental in the creation of RazEr. Not only did it 3d print the entire front fork, but now it’s serving as a convenient epoxy curing oven. I set the head and platform temperature to about 50 celsius each, and left the can on it overnight. This temperature isn’t enough to damage the magnets, but ensures that the epoxy sets thoroughly.

Seriously, what did I do before this thing? It’s really in need of an update.

The next day, it was time to pop back over to the Edgerton Student Shop (where Nice Things exist) to make the internally threaded wheel locking ring. They had the only internal threading bar that I knew of…and that wasn’t broken.

This recent build should probably be entitled “Charles samples a different lathe on every part”: The machine of choice of the shop is the revered Monarch 10EE, the later type without the big round knob. It’s nice.

Maybe next time I’ll pop over to the CSAIL Machine Shop for their Hardinge HLV-H.

The internal threaded Ring of Wheel-Retaining.

I actually had to make this twice, too. For one reason or another, my motor can was turned on 22 threads per inch, not 24 like I thought. I might have just been off by one gear after looking at the selection grid from the wrong angle. Regardless, my x24 thread did not fit, so I had to cut off a chunk and start over with a x22.

And this is how it goes on.

This is actually the wrong direction – the correct direction is with the chamfer facing outwards away from the wheel. What I discovered, though, is that it will thread on just fine in this orientation, but can only make it 3 or 4 threads facing the other way before it just locks up solid. The threads are definitely not crossing, since the initial engagement is smooth and there’ no resistance for several turns. But then it suddenly becomes very high friction – not even thread lubrication helps, and I’ve definitely cleaned this thing 5 times over.

I made a thread diode. What the hell?

Oh well – another engineering pass in the form of “let’s just keep it this way” is pulled.

While reinstalling the stator, I lost control of it under the magnets’ massive pull and it ended up slamming into the far endcap, shearing 4 of 5 sensor wires. Fortunately, this happened at a point which was outside the motor, so I was able to quickly repair the broken wires.

Instead of fixing the can in a drill press vise and slowly lowering the stator into it using the quill, I just held the two. Maybe it worked for tiny motors, but it definitely does not work for a motor like this, and I could have sheared off a fingernail or broken a bone.

tl;dr don’t beast large motors by hand.

And the wheel reinstalled. Black and gray wheels coordinate with the color of the scooter better, IMO.

Pursuant to this, I stole the front wheel and fork off the temporarily defunct Straight RazEr. So here is the finished conversion, except still with its shady-e-bike-troller tumor since I have not gotten around to repairing the melontroller yet.