At this point, I doubt I’ll have time to get to Pop Quiz<\/a> at all. I thought Nuclear Kitten had required only a re-magneting, but it turns out the motor needs a total rework. Additionally, I need to reconsider the drive motors, since I went through two gearboxes last year and do not have any spares at the moment.<\/p>\n The insect status for Dragon Con<\/a> is therefore tenuous.\u00a0 NK is a second priority after \u00dcberclocker, and only if I think the design is going to be solid. Two events of last-minute rushing have sent me the message that last-minute rushing makes robots not fun.<\/p>\n Hell, if \u00dcberclocker doesn’t make it, I’m just going to D*C for the sake of going to D*C. Maybe I can actually take some pics this time.<\/p>\n The build has pretty much reached the point where I’m the only bottleneck. That is, I have to fab all the rest of the part, and I’m slow compared to a CNC anything.<\/p>\n Yeah, I consider that “slow” now.<\/p>\n It’s time to start filling in the pretend-o-bot!<\/p>\n The “shocks” for the springy front legs. These are, like on \u00dcberclocker 1, post-op’d waterjet parts. I actually had to rework this design on the fly because I ordered the wrong kind of shoulder screws – 5\/16″ diameter instead of 1\/4″. The problem was that my springs had a 1\/4″ rod-fit size.<\/p>\n Ever machine a spring? It’s not pretty, but a 5\/16″ carbide endmill chucked in a lathe tailstock made pretty short work of it. I was expecting some epic disaster with the spring unwinding or just exploding out of the chuck.<\/p>\n This is the leg arrangement with the ‘shocks’ in place. I thought 100 pound\/inch springs were going to be too stiff, but the high lever arm ratio of the linkage means the whole thing is still pretty bouncy.<\/p>\n More little shiny round things are now appearing around the robot. These are the drive “standoffs”, which function as dead axles. I formerly made these part of the robot structure, but it was an epic pain undoing the screws which held the body rail\/panel to the standoff. Therefore, I just made a shoulder which sits in a bore on the outside walls of the robot. It’s not entirely structural, but will resist cave-ins (from impacts) to a degree.<\/p>\n I did end up putting a threaded hole on the outside end just in case I changed my mind.<\/p>\n The standoffs were made from 12L14 steel, which is something like two beans and a lollipop per six foot rod on McMaster. I have a new appreciation for this stuff – it’s like… steel, but it machines like aluminum.<\/p>\n Then again, how much should I be trusting steel<\/em> which machines like fucking aluminum<\/em>?<\/p>\n Hubs!<\/p>\n Well, these are actually functional prototypes of hubs. It was easier to pop four off in one cycle than to switch back and forth between machines, completing one at a time.<\/p>\n Completed hubs, with sprockets. Remember those sprockets with the weird double-D shaped bore? Now you know why.<\/p>\n Simple retainment and power transmission with the aid of the DD and a snap ring. I used to hate retaining rings (snap rings, C-clips, etc…) with a flaming magnesium passion. But after getting a set of snap ring pliers<\/em> I realized they were the most compact and cheapest way to keep something axially where it should be.<\/p>\n So now I love snap rings. The cool thing is that the sprockets are easily removable, so I can press the wheel on later. This was just an assembly test.<\/p>\n … but wait, what do you mean the chain doesn’t go in my sprocket teeth?<\/p>\n I highly doubted it was a pitch\/scaling issue, since some times the chain was able to wrap all the way around and other times not. I suspected that it was more a building up of small incremental errors made by the waterjet as the c hain went around the circle.<\/p>\n The solution was as simple as giving each tooth a really quick flick over the open section of a belt sander. After that, it was still sort of rough, so…<\/p>\n … this is TOTALLY LEGIT GUYS I PROMISE.<\/p>\n I am under no circumstances endorsing this kind of behavior.<\/p>\n Yeah. Right. Anyways, chuck one hub in a powered spindle of some sort (I had a convenient one 10 feet away), and put the other hub on a little axle that you can grab onto.Link the chain between the two sprockets and power the machine on.<\/p>\n Assuming you haven’t been sucked into the spindle yet, pull on the axle, hard<\/em>.<\/p>\n This sort of grinds the chain into the sprocket teeth and forces it to round out imperfections just by virtue of being under balltastic tention. I was only limited in the pull force by the fear of the whole lathe rolling over onto me.<\/p>\n The sprockets ended up pretty smooth.<\/p>\n\u00dcberclocker Remix<\/h2>\n
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