equals zero

Over the past few days I’ve been mostly hanging out at the Georgia Tech Invention Studio. I was nominally there as “guest lecturer”, but I don’t quite think their own 2.00EV is organized yet to the point where I can feel comfortable with that title. All the ‘students’ are actually lab instructors (similar to our MITERS keyholders), so there wasn’t that much ‘teaching’ to do. I did hold some impromptu lecture-like things and generally advised people on their builds where needed (and fixed the waterjet?). Regardless, some… interesting products are coming out of it:

It’s literally twice as long as some of the other scooters.

I’m back now, and one of the first things on the agenda is getting the half-assembled repackage of RazEr up and running. I sort of left this in the middle of construction when I zipped off to Atlanta for the weekend. I had the frame ‘box’ assembled to test fits, but I pretty much had to take it apart again to actually install stuff. My direction was essentially assemble the major subassemblies first (make the fender, reinstall the motor, attach the front end) and then lob the electroncis back in as-is, since it worked fine before.

Here’s the fender in place with its leaf spring installed.The ‘sheet metal work’ was done on a vise, then fitted in place using just tightening screw pressure. 5052 aluminum bends very easily, especially in 1/16″ thickness, so I was literally just leaning on the part to get the bends I wanted. To do the large radius sweep at the top, I bent little by little in ‘facets’ which weren’t drastic enough to be seen as disrete (though you can kind of see it).

Now that I’m a little more comfortable with making sheet metal geometries compatible with other 3d solid parts, I might incorporate it into more builds in the future.

The fender is just mounted on a chunk of 1/4″ threaded rod. Nothing fancy at all this time – no spacers, even. The pressure of the leaf spring alone is enough to keep it in place reasonably.

More progress has been made on frame assembly, with the folding joint  reattached now. I traded the former front end for a new A3 type front that was part of the leftovers from my 2.00EV. It’s substantially less beat to shit and doesn’t wobble as much, and I swear it’s a little taller than the one I had before.

I had a left over new fork from building Straight RazEr (whose wreckage has since been donated to Kramniklabs) which I dug out for this build.

I forgot to take a picture of what’s going on with the 5″ colson wheel, but there is actually a type 1614 bearing bored into each stock Delrin bushing. The Colson comes with a 5/8″ bore bushing  that has a 30mm OD (which presses in to the 30mm bore of the wheel itself). I tried to find a > 30mm bearing that wasn’t of a ridiculous axle diameter so I could bore it into the wheel directly, but gave up and went the other direction instead.

A ‘stock check’ of bearings I had turned up some R8 type and 1614 type bearings. Both were 1 1/8″ outer diameter, which I could bore into the Delrin bushing, but I settled on the 1614 bearing since I easily located a stock 3/8″ bolt to serve as the axle pin.

The job itself was done on tinylathe, which is probably one of the handiest tools I’ve ever worked with.

Moving on to the electronics deck now, I put together the ‘switch panel’ which holds the charge and controller ports as well as the annoyingly bright blue LED endowed power switch. The idea is to have BAT and PWR jumped externally with a Deans ‘patch cable’ so I could jack in a flow-through measuremen device like a Wattmeter if needed. Else, the switch is to serve as the primary turn-on mechanism.

It’s better than the yank-the-battery-connector setup RazEr Rev has used since forever, but I’m wondering how long until this switch falls victim to no-precharge arcing damage like the very first switch arrangement.

The interesting part is on the back. Instead of connecting the switch’s built-in LED to ground directly, I threw a 100 ohm resistor on it. This should prevent the light from exploding right away, as it happens when you try running 12v rated switches on 36 volts… Otherwise, there are just a few select wire jumps which bridge the two Deans ports through the power switch. Note the back-to-back soldered Deans connectors on the right…

With the switch panel done, it’s time to load all the electronics back in. The same shell-less Jasontroller appears, bolted to the aluminum frame directly for some heat sinking. There’s a bit more space for batteries this time, since they can reach all the way under the folding joint, but unfortunately it isn’t enough to actually add more cells – just maybe some padding. If I wanted more battery energy about the only good option is moving to prismatic cells.

With everything wired back to the way it was, I shoved the 3d-printed front endcap on. This was one of those pieces made on the Lab Replicator™.

And the repackaged shot. Unfortunately I gave away my only other black Colson wheel, so it’s gray for now. When I get another one (or get it back), the bearings are transferrable.

This frame rides significantly lower than RazEr Rev – too low, actually. This is likely due to a difference in head tube length between the A3 I got like 5 years ago (for the original RazEr!) and now. RazEr Rev rode slightly ‘nose up’, but this one is definitely nose down. The clearance at the front is about 3/4″, decreasing to less than 1/2″ when I’m actually riding it and the rubber block is compressed.

Not going to work. I’ll compensate by making the two wheel fork sides a little longer. In the mean time, it is rideable, and handles just like it used to except with more stopping. And less exposed wires – check out the 3d printed wire guide at the lower right.

I mentioned last time during the Great Project Purge that RazEr rEVolution was due for a rebuild very soon. I don’t actually plan on calling it RazEr Repackaged, but that’s pretty much what’s going on here. Like the rebuild of Kitmotter, it’s intended as a literal repackaging of parts I already have – a case mod, I suppose. The goals of this rebuild would be to update the frame to a new construction style that I’m favoring more, as well as to clean up some other design loose ends like adding a brake (mixed-up priorities, anyone?) and building in support for the Jasontroller.

The new frame is of roughly the same dimension as RazEr Rev(1?), but it is no longer made of 1/4″ plate for the sidewalls with exposed T-nuts. Instead, the whole structure is 1/8″ aluminum now. Not only does it save weight by reducing unnecessary material use in the side walls, but it opens up the interior volume a little more. The “cavity” for controller and battery is also about half an inch longer. The 1/8″ plates will be attached together with corner blocks similar to those I used in NK.

Additionally, there’s no more structural vs. nonstructural top plate. The black Garolite deck of Revolution is gone in favor of a single top plate and the silvery metal look (changeable with selective application of grip tape or paint).

The first subassembly I put details in is the thing that RazEr Rev never had: a fender brake. By that, I mean it neither had a rear fender (until I appended one crudely) nor a mechanical brake. This being the revision that I hope to address shortcomings, it’s going to get a brake.

I finally spent some time to figure out the way that Inventor processes sheet metal geometries so I could make properly mating sheet metal parts. The side of the sheet metal that you make features on really matters, as does the role of sketched bend lines (start-of-bend, centroid of bend, etc.). Yes, I’ve used Inventor for like 7 years without really touching sheet metal features in depth.

Not shown in the above image (but in the one below) is the spring for the fender – it uses a simple bending plate of spring steel instead of a torsion spring due to the limited space under the fender.

There’s other trimmings to be added too. Instead of a Deans shaped hole in the side plate, I’ve just opened up a big rectangle and will be using 3d-printed electrical panels. Right now, the configuration is for two Deans and a switch. One connector is a battery connection and the other goes to the controller – this way I can easily jack in a Wattmeter or similar. Should I decide to change wiring arrangements, the electrical panel is reprintable.

The motor wiring will be hidden behind a 3d printed cover. While not Apple-like, this at least cleans up the exterior wiring of the vehicle substantially. I’ve been entertaining the idea of a “kit-class” scooter based off RREV for a while, so maybe this rework will move towards that a little more.

The front fork remains the same from the old frame, since it is a solid design. Here’s the front posed roughly where it should be. One of these days, I sweeeeaaaar I’ll model up a handlebar from a Razor scooter.

I cut the frame out of 1/8″ 5052 aluminum. One of the main reasons for moving to all 1/8″ on the frame was the fact that I could get the sheets for much less – they tend to show up more on the surplus channel for one reason or another, 5052 even more so. 5052 is about 2/3rds as strong as 6061-T6, but the vertical height of the material is still more than sufficient to carry the loads I need. 1/4″ 6061 just didn’t make sense any more in the side plates.

This time around, the attachment for the front folding joint is done through a “clip” which makes a material-to-material interface. This opens up space underneath the folding joint which would normally be taken up by a giant nutplate, but this time I can scoot the batteries forward under it. The method is decidedly less stiff, so a “backup plate” of another 1/8″ thickness is also clamped underneath.

1/8″ is too narrow to hold T-nuts directly, so I’m using some 1/4″ to make corner blocks.  I probably didn’t need to use this many either, but it was an easy linear pattern to make. The backup plate is seen at the lower right.

Another Classy Thing I’m putting on this version is a 3d-printed “endcap”, similar to the ones found on stock Razor scooters. For this version, I just used the theoretical outline of the corner blocks and internal plates, which means it doesn’t actually fit if the frame is fully tightened and assembled since these dimensions are compressed a little. It’s not supposed to be waterproof; just a splash guard.

Once the frame is done, I should be able to throw it all back together in a day.