I started this project with a goal in mind: test microswitches. Specifically, test the brand of microswitch that I chose for an exhibit I worked on last year. When I was younger, my dad used to have a subscription to Consumer Reports and I remember years ago reading about how they tested things, like using a machine that opened and closed laptops repeatedly to see how many times it could be done before it broke or wore out. One of my goals is to do that sort of thing, but with things we build for exhibits. This is a start. (And yes, I’ve considered just buying/building a robot arm to do these things… I may still do that!)
Meanwhile, since I’m 3D printing again (a lot!) I figured I’d design and print the parts for this machine. Not all the parts… some parts are scrap wood, and (in a recent version) home-made recycled HDPE. The first iteration was a total hack job, and it worked. Sort of. I get in this habit of trying to do press-fit parts, but then I remember that’s a bad idea, so… upgrades happen.
The first version used a PLA plastic arm. Eventually it started to scrape and wear away, and squeak a lot. It was annoying. (Bearings got added to a later version, along with a proper set screw.)
One thing I found out about the cheap microswitches is that the metal arm would bend, and then stop pressing the switch. That’s no good (but good to know.) Then I found times when the switch just wouldn’t trigger the Arduino to advance. Switch failure after just a few tens of thousands of presses? Maybe.
I also had Arduino problems! At some point the cheap eBay Arduino UNO clone from China gave up the ghost and just stopped working reliably. Then I could no longer upload code to it or connect to it at all. Replaced that too!
I also played around with the switch angle… as demonstrated in the above and below photos. I also considered a spring-arm sort of thing the switch could ride on to allow some flex, which would be interesting, but probably less of a real-world test. Maybe.
Here’s a video compilation of some of the testing from early on. This is when I actually thought I could just slap something together and it would work reliably. I’ve since been proven very wrong. I’ll be writing more posts about the changes this machine has gone through and where it stands today. In the meanwhile, if you check out my Instagram or Facebook account, I often post in-progress/sneak-peek photos and short videos.
1 reply on “A (not quite) Useless Machine”
Cool testing machine!