I think I have found the mistake. the heatbed is higher at the corners than in the middle, it hangs through. I have ordered a new one now. I hope that works then. did someone already have this mistake?
Maybe the bed screws are all too tight, that can cause distortion or warping of the bed plate. Technically you only need 3 points to level a bed, but since we have 4 screws, it is over constrained and easy to warp.
Well, glass is normally perfectly flat. It may be that the aluminum bed warps when heated, this is common for cheap rolled aluminum (cast aluminum doesn't warp when heated). Or it may be that the springs and bed screws are warping the bed.
Over constrained systems will always be imperfect - for example, if you try to draw three dots in a straight line by hand, and then join two of the dots, the third dot will not be perfectly in line with the other two. Two points define a line, three points means the system is over constrained. For a plane or a flat sheet, you only need three points to support it. But on this printer we have 4 screws - so it means that unless all 4 screws are perfectly positioned, they will be exerting a warping force on the bed. In some ways this is good, as it may allow us to correct for any warping that occurs during heating, but it also makes achieving a level bed more difficult.
A good article on problems with overconstrained systems, with some simple diagrams can be found here:
Sam, does the babystepping require to be enabled additionally somewhere? My "baby Z+" and "baby Z-" switches are gray (maybe it's normal) and I can't see any effect of working.
I haven't change anything in the code related to this, the section remains as downloaded the firmware:
#define BABYSTEPPING #if ENABLED(BABYSTEPPING) //#define BABYSTEP_XY // Also enable X/Y Babystepping. Not supported on DELTA! #define BABYSTEP_INVERT_Z false // Change if Z babysteps should go the other way #define BABYSTEP_MULTIPLICATOR 5 // Babysteps are very small. Increase for faster motion. //#define BABYSTEP_ZPROBE_OFFSET // Enable to combine M851 and Babystepping #define DOUBLECLICK_FOR_Z_BABYSTEPPING // Double-click on the Status Screen for Z Babystepping. #define DOUBLECLICK_MAX_INTERVAL 1250 // Maximum interval between clicks, in milliseconds. // Note: Extra time may be added to mitigate controller latency. //#define BABYSTEP_ZPROBE_GFX_OVERLAY // Enable graphical overlay on Z-offset editor #endif
Also don't catch what efect should have with double-click. When do double-click on the status screen (well, maybe I don't know which one it is) - not any reaction. Can find baby switchec in More menu but as said - seem don't work.
Here I also have a bit strange effect. When having pronterface connected then start printing from LCD - the bed heater starts but heater extruder (it runs when I take off the usb cable). Heater extruder always starts when printer is stand alone. Ok I will check it tomorrow (it's 2am here) to start printing stand alone (LCD) then connect pronterface to test babystepping..
But can you tell me pls:
- status screen is the first screen apearing after "start print" and if I tab it twice the screen should be redirected to the screen with baby switches??
- baby switches what colour shoud have? Gray or blue - it seems to me I saw blue on your video. Gray means "mot active" or it is just gray without any meaning?
I did not even know about that option! I think that may be for printers with a rotary dial, but I am not 100% sure. I don't know if it applies to our situation. Yes, you need to flash the LCD again.
Regarding to the thread name I have the question how in fact is (or should be):
- making HOME we store the Z as Z0 level
- at this position we do leveling using paper or 0.1mm feeler gauge. So bed is at Z-0.1
- now we create slicer gcode with first layer thickness 0.1mm. In gcode file I see the first layer is printed at Z=0.1. So nozzle is 0.1 over zero and bed is -0.1 under zero. So distance bed to nozzle is 0.2 while layer is calculated to be 0.1mm.
The question is how it is possible to print layer 0.1mm being 0.2mm over the bed? Is it proper distance or I have something wrong generated by slicer? Should be not first layer printed at Z0 in this case?
I think when you level so there is some friction between the nozzle and bed, the paper is actually pushing down on the bed ever so slightly (z= -0.1), but after removing paper, the bed rises again (z= 0.0). That's my theory....
I also thought 80GSM Paper is a little less than 0.1mm, closer to 0.07mm.
I think part of this reason is also that the flow out of the nozzle needs to have some small additional height above the surface for the filament to curve and flow, from travelling straight down, to being deposited in lines.
Comments
All four screws are easy to screw in both directions.
#if ENABLED(BABYSTEPPING)
//#define BABYSTEP_XY // Also enable X/Y Babystepping. Not supported on DELTA!
#define BABYSTEP_INVERT_Z false // Change if Z babysteps should go the other way
#define BABYSTEP_MULTIPLICATOR 5 // Babysteps are very small. Increase for faster motion.
//#define BABYSTEP_ZPROBE_OFFSET // Enable to combine M851 and Babystepping
#define DOUBLECLICK_FOR_Z_BABYSTEPPING // Double-click on the Status Screen for Z Babystepping.
#define DOUBLECLICK_MAX_INTERVAL 1250 // Maximum interval between clicks, in milliseconds.
// Note: Extra time may be added to mitigate controller latency.
//#define BABYSTEP_ZPROBE_GFX_OVERLAY // Enable graphical overlay on Z-offset editor
#endif
e.g.
maybe the print is paused?? I'm not at my printer right now sorry.
Best,
Sam
I think part of this reason is also that the flow out of the nozzle needs to have some small additional height above the surface for the filament to curve and flow, from travelling straight down, to being deposited in lines.
Great questions @netzmark!
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