by RetireeJay » 2018-May-Sun-13-May
I have occasionally had both Repetier and Cura (or another User Interface) program open at the same time, but I'm always very careful to not allow more than one program access to the printer simultaneously - even if only one program is actively running a print. 99% of the time, I only have Repetier open. I only open up Cura to try to analyze problems posted here. Why would you have both Repetier and Cura open? Repetier gives you access to the "Cura engine" for slicing (at least, the Windows version of Repetier does; I can't vouch for the Mac version).
That said, I've never seen a "k" message. A loss of communications could stem from a problem with your USB port or cable; it could be a side effect of a power supply that's overloaded or failing. Or you might have a thermistor wire that's becoming slightly intermittent due to wire fatigue, although normally that causes an immediate and complete shutdown.
Come to think of it, I'm pretty sure the communication protocol between the computer and the printer involves the printer responding with an "ok" message after each line of G-code is received and successfully executed or buffered. So if there is a poor communication connection, maybe the "o" is getting lost and only the "k" shows up. Repetier doesn't show you all those "ok" messages because it knows about them, but if it sees just "K" then it doesn't know how to interpret that and probably would show it to you. Which leads to the question of whether you have something else going on on your computer that might keep the CPU so busy that it misses incoming characters now and then.
Printrbot Plus operational January 2013
Brass threaded rods (5/16" X 18) & nuts for Z axis
GT2 belts & pulleys
Cable chain to reduce probability of fatigue failure in wires
E3D V5 Hot End, 0.4mm nozzle, also 0.8 and 0.25 in use occasionally
PB fan mount + 40mm fan -- using printed mount adapter, not the E3D supplied fan
Injection molded extruder gears
Optical Z "endstop" (custom designed and built)
Have used many pounds of T-Glase filament. Now also doing some work with Ninjaflex SemiFlex
Print on glass with Scotch Craft Stick or other glue stick
"My next printer is..." Prusa i3 MK3, upgraded to MK3S