Well, it’s not actually new to the University, but it’s new to me. I’ve known we’ve had it for awhile but I’ve never had a chance to play with it. Before now, pretty much every project I’ve needed to create was better made on a CNC, lathe, or 3D printer. That changed when I broke the legs on my hexakopter last week and new ones are too expensive.It seems like the legs that came with the kopter were designed to reduce as much weight as possible. This would make sense if we were really worried about weight, but the motors are strong enough that a few more ounces wouldn’t make a difference. If you land perfectly, they’ll work all day, but if you land while coming in sideways, you’ll lose a leg every time. So far I’ve broken three legs and balancing on two is unsurprisingly difficult.
After the accident last week, I flew without legs for awhile but this is playing with fire and I’d prefer not to keep doing it. New legs are $20 a piece which is way more than I want to pay when I know they’re going to break again. I could print the legs on our 3D printer but I think it’s just a little too small and they would cost almost as much as legs from the factory. I could mill them out of aluminum but that would be about $15 a piece. Milling them out of plexiglass would be cheap and easy, but I’d have to file down some of the corners. Not a big deal but… if I’m using plexiglass anyway and it’s a two dimensional part, why not learn a new skill.
I found some spare plexi in the machine shop (FREE!!!) but there wasn’t a ton of the correct thickness so I didn’t want to waste it and decided to practice first. I went into my creative folder and pulled out two old files: one that would make a good solid piece cut out and another to engrave.
We are using an Epilog Mini 35 watt laser that is hooked up to the computer as a printer with special drivers installed meaning that you can engrave or cut from any program. If a line in a program is less than 0.007 inches in width, it is treated as a vector and is cut. If anything is larger than that, it is treated as a raster and is engraved. There are separate settings for engraving and cutting to determine speed, power, and frequency.
For the engraving, I don’t remember the exact settings, but I ran it through three times in order to get a deep enough engraving. If I had known it was going to turn out this well, I probably would have engraved something more important, but hey, that’s what tests are for. This is my “Super Ketchup” logo I made a while back while first learning Adobe Illustrator. The white area is that area cut away from the acrylic. After three passes it’s about 1/16 of an inch thick.
Next, I had to figure out the right settings to cut through a 9mm piece of acrylic. The most our laser has ever been used for is 5mm so it was a little tricky. We ended up doing two test pieces before finding the right settings. Really, it was very simple, we just treated it as three pieces of quarter inch plexiglass so we did three passes at 4% speed and 100% power with 400Hz frequency. We got very little scorching and the edges look fabulous.
So, while I’m far from an expert, I am definitely learning. If you’ve got any questions or ideas for me to try, let me know.