cpkmc

I am running Linux Mint 18, and have a Prusa i3 printer. When I open Cura 2.7 (64 bit), it does not recognize my USB printer. I tried to just print with an SD card, but that gave me crazy results (didn't heat bed or nozzle, printer moving around 5 inches above bed...). Should I be using an earlier version of Cura? I had previously (successfully) been using 15.04 with an old Windows 7 machine, so I tried to install that earlier version in the new Linux system. But after I uninstall the Cura 2.7, the older version (15.04) of Cura does not want to install. I'm stuck!