Answering questions from (appreciated) responses:
Steve: It could be a bug, it is old firmware, but it seems unlikely unless it was a “time bomb”, nothing in any settings changed either in firmware or software.
Mark: Yes, I do home at the start of a script - I am schooled to what happens if you don’t…
Here is a more detailed update of my problem after my investigations:
My setup:
Folger Tech Kossel 2020 delta printer running Marlin firmware ©2011 from the kit maker
Running Simplify 3D on a Win 7 computer
Until yesterday, my delta printer was “dialed in” and printing whatever I threw at it. My bed is flat, auto-leveling was working like a charm. I have a part fan that is off for the first layer and set to 50% at layer 4. My bed is at 60 C and my hot end is at 210 C for the first layer and backs off to 200 C for all layers after that. I work in PLA.
Then, total dysfunction.
Problem one:
I found that suddenly all my endstops, leveling data changed. My bed used to measure out (X,Y,Z,0) at 1.1, 1.1, 1.1, 1.0. I am using a zero-offset magnetically attached mechanical switch to do the auto bed-leveling. I then measured the “new” bed level stats at 1.4, 1.4, 1.4,1.3, and the Z offset of the probe obviously moved.
As I re-leveled everything to find the new settings, they changed and finally settled to 1.2, 1.2, 1.2, 1.1.
Huh? Why did these all change, and why did they settle back down (most of the way)?
I updated my configuration.h file and kicked some prints off. This almost worked. If I have flat objects with large contact area-to-height ratios, the print will work. Things that have multiple, smaller contact points will not print, by about the 20th layer the print head will snag on something and pull it off the bed.
This brings up problem 2:
Even flat models now are festooned with “cobwebs”. Gunk gathers and creates “zits” in places and more scars than usual on surfaces. The plastic may warp on a layer and when the print head comes along may hit it and knock it off. Also, it may be dragged around by drools from the hot end. I now see dark sections that look like the plastic got burned while coming out.
OK. I am clueless about Problem 1, I checked my mechanics, no loose or broken rods, my bed springs didn’t suddenly relax and come back, my carriages are solid, no loose screws, my limit switches didn’t move (they’d all have to move at once since the error distribution was consistent at all towers). The belts are the same tension and nothing that I could find was changed on the end effector.
Problem 2 looks like a classic case of the PLA getting too hot: strings, warping, burned spots, drool dragging. But why all of the sudden? My settings over the last two weeks, when I got my printer working, have not changed. Is it possible that the thermistor is failing and the temperature of the hot end is getting hotter than what is being reported?
regards,
DLC
