7 More Days To Zero-G: Parts!

I’m once again writing a blog update after 11pm, so unfortunately this is going to be super brief. I’ll actually take time to get pictures and videos up tomorrow, but here’s the highlights:

  • We finally got to meet Forrest in-person. He’s now out here for the remainder of the sprint, and then will be joining us again a few weeks later as our intern this summer.
  • Colorado Plastics here in Louisville got all the plastic pieces we ordered yesterday turned around quickly. We got the acryllic pieces solvent welded together, and everything else fit up pretty well.
  • The sheetmetal arrived from San Jose. We used a company, Hill Manufacturing that had done a lot of work for us in our Masten days. They did a great job other than a qty I miscommunicated, which got us two of one part we only needed one of, and one of one part that we needed two of. We found a local sheetmetal fabricator who we’re having make us a replacement bracket, and in the meantime it turns out we can kludge a stand-in by dremeling out the extra one of the other brackets. It isn’t perfect, but it should at least allow us to do testing while we wait for the replacement part.
  • Thanks to my friend’s suggestion, we were able to get sources for the two drive components we forgot to get sourced last night. We gave him the drawing this afternoon for a rather complicated bracket that ties the face of the gear motor to the sheet metal while still allowing space for a pulley/timing belt, and he turned it around by this evening. Probably can’t always count on that fast of turn around, but it’s good having another machine shop that we can count on for quick turnaround prototyping.
  • For the human interface “joystick” we need to make, Forrest suggested the cool idea of hacking* a Wii Nunchuck controller. It has the forward/back potentiometer we wanted to control boom deploy/retract speeds, and it also has two trigger buttons like we needed. We’re going to see if we can remove the digital smarts, and directly patch into the analog outputs from those switches. We’ll also need to find a way to mechanically attach this to the boom deployer. In case that doesn’t work, we also ordered some structural tubes and switches to make a less cool looking but lower risk backup.
  • AJ finished up the design and detailing of the 2B gripper design, and we got details worked out for getting those parts made and the pads made for them too. Right now it’s looking like Tuesday for integration and testing for the gripper and EA pad components. That barely gives us a little time in case we need to do another iteration, but at least does give us that margin.
  • We also got the ribbon cable ordered that we want to try out for connecting the boom-end electronics to the boom deployer. The boom we got has a “Cordura” type cloth covering over most of it, except for about a strip down the middle of the inside of the “tube”. It looks like the ribbon cable will be thin enough that it may actually be below flush with the Cordura cloth. We still have to do some work on how that terminates on the boom end, and the exact implementation of how we do the transition in the boom spool can, but it looks like this may be resolved soon.
  • We missed the McMaster deadline last night by about 30 seconds, but ordered in all the drive components we need for delivery tomorrow.

Ok, tomorrow is a big integration/test day, so hoping to hit the hay soon. Videos/Pics tomorrow!

* I’ll go more into what I mean by hacking, but someone offlist pointed out to me that hacking has some negative connotations to non-engineers. Basically we mean modifying the Wii Nunchuck to do something it wasn’t originally intended for. Stuff like routing wires to bypass the internal microcontroller, making structural modifications to turn this into a fixed-mount joystick, and changing the output connector to something non-proprietary. Perfectly legal and above-board stuff (unlike the sort of “hacking into networks” kind of stuff you may see in the movies), but when you make those sorts of modifications, engineers often call that “hacking”.

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