The next stage of development is in progress – I got most of the code running on the test jig this week, and once I got it to a point that most functions seemed to work – it was time to put it into a practice jig. But before that happened, I got two micro switches to use to detect when the drill platform hit the far right and left points. Originally, I was just going to mount these so that I could tell when the drill platform hit the ends of the carriage box. Now I’m thinking that it would make more sense to attach the switches to a movable arm to set the ends of the pen blank. That way I can manually set the cutting length – and not have to write code to set the endpoints each time the blank is changed.
The carriage box has a minor modification to the way the drill platform is raised and lowered. Originally, a square shaft was going to have a cam installed on it, that would slide with the platform, and the cam action would raise and lower the platform when the square rod was twisted. As we thought about it, the likely hood that the cam would bind on the shaft when moving seemed pretty high. So instead, a servo (tiny one!) is mounted to the back of the platform, and the arm presses against a simple round bar in place of the square bar. (We could have just left the square bar, but the round bar seems like it made more sense (and it cost less to do it that way as well 🙂 ).
So, as you can see, the carriage is assembled now – and the next phase of testing is underway. The biggest issue we have right now, is that the current rotation speed for the drive screw is just too slow. I need to investigate this to see if it’s my programming, a drive shield issue, or just something we’ll need to address with another hardware/gearing solution. In the mean time, the rest of the programming for the various patterns is underway. I plan to turn a simple cylinder out of an acrylic, and tape paper around it – instead of the drill, I’ll clamp in an ink pen to more easily visualize the patterns. Once I’m happy with those patterns – I’ll work on installing the drill for the final testing of prototype #1!
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