Robotics Weekends: Jan 26-27 & Feb 2&3

Written two months ago:

“Jan 26-27 weekend was pretty productive, although very long. I started by going to pick up lumber. I figured it would take maybe half an hour to go there, throw lumber in the back, and drive home. NOPE. The person I arranged the deal with wasn’t there, so no one was expecting me. It took ages to get the lumber pulled, and then they very, very kindly chopped everything in half so it would fit in our car. Except the 4×4 sheets of plywood wouldn’t fit in our car. Luckily we had top rails and crossbars so that we could put them on top, but it took ages and ages to get them tied down and secure because the top rails are not actually meant for tying down. The side rails are flush with the top of the car. Great for a Thule, I guess! Made things far more complicated for us. Whatever. G went and bought rope, handed it to me, and I went nuts. And failed two or three times because there are many possible dimensions of movement, and the things I tried weren’t effective in all of them. We FINALLY got everything loaded up. Then we FINALLY got all the paperwork done. Then we FINALLY got on the road. The whole trip ended up taking an hour and a half, but by gum we got the dang lumber! Now the kids could continue building the game pieces we need to test the robot that was nowhere near done being built! Yet.

Once we got back to campus and unloaded the wood, it was time to start putting parts on the chassis we’d completed previously. We needed to get two gearboxes mounted, and they had to be precise to the holes we milled. The team struggled to cut holes that were perpendicular, so I ended up needing to create a jig to help us cut the holes all the way through the 2×1 as straight as possible. Gearboxes done, motors done, we’re nearly ready to put on wheels. Woo! Except that the gear box didn’t have a shaft long enough, so we spent a ridiculously long time trying to figure that out. We ended up using a pulley as a shaft coupler on the drive wheels. That was was the most challenging everything to get together because there was so little room to see for alignment. I made the holes for the bearings on the mill to exact size in hopes that they would stop falling out. Turns out making them the exact size of the bearing made them almost impossible to get in, but once they were in, they fell right out. Son of a gun. Lesson learned. EITHER make them a little bigger and collar clamp those suckers in, or make them a little smaller and actually press fit the damn things.

But! Drive wheels on! Pulleys and belts on! Now it was time to put on the front and back wheels, which should be easier, right? Because there’s only one pulley instead of two, so there’s way more room! Hilarious. There’s more room, but so many things were either a tight fit and nearly impossible to get installed OR so loose that they wouldn’t stay where you put them, plus with the bearings already in getting the shaft lined up with the added tension of the belts in addition to all the things being kept aligned made it nearly impossible. There were three of us working on it, and we traded out three times each on each wheel before I finally got it to fit in just right. I don’t know how I became the shaft/bearing whisperer, but I would really like to give someone else that job. By the end of Saturday, which was 5.5 hours AFTER the rest of the team left, we had gotten three of six wheels installed. And then were super duper done.

Sunday, we got back in the trailer and kept on keeping on. It took many more hours and quite a few improvised tools, but we finally got the other three wheels on. To get the wheels tensioned enough to let us line up the shafts, we first tried clamps. That worked ok (as in it worked after hours of shouting at it) for the two back wheels, but would not work at all for the two front wheels. I ultimately made a tourniquet out of some strapping and a spare piece of 2×1. Twisting the 2×1 shortened up the strapping and pulled the wheel over enough to make it do what it was told. There was also a lot of things being stuck and not easily moving, so we had to try a ridiculous number of options before we figured out something that would work: use collar clamps instead of spacers so there’s more shaft exposed, and then use those collar clamps to hold up the things on the shaft, force it down just a little further, move everything up, and then move up the collar clamp, effectively walking the wheel and pulley up while walking the shaft down. It was brutally tedious and required a lot of me laying flat on my belly in the floor of the trailer, but IT GOT DONE. NOT DONE PRETTY. BUT IT WORKED.

And holy smokes will we make some different choices next year. So many different choices. All of them.

The week was spent testing electronics on the drive train and making new parts before we reached a new impasse that required welding. The weekend was a bit of a wash, because there was another storm and no power, so we couldn’t get the welder in to help us out on Saturday. Sunday was another four hours in the trailer trying to get absolutely everything ready and set up to be welded. It was a lot of milling and measuring and s”

I have no idea what else I was going to say about these weekends, but there’s what I had in my drafts from two months ago. Figured I’d get these cleared on out and get started again next week without a backlog.

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