bed still not levelled after G29

Hi everyone, I have an issue with my SmartCore (RepRap, Marlin) 3D printer. It has the G29 feature to level the bed according to a probe, but it does not compensate for what it should at the back of the plate.

- I tried to over "de-level" the bed (like 2cm and it still compensates so the G29 command works) but in any case, the back is too close to the head, and the front is fine.
- I replaced every pieces of the X-Y axis yet the issue remains.
- I use aluminium tape under my glass bed for probing.
- It is a Core XY printer (see image attached for more details)

Do you have any idea, even the smallest, to my problem ?
Does an individual offset for each 4 points probed exist in the firmware ?


Thanks a lot guys


pictures of the problem here :
overall printer :


bed from front


bed from above


Edited 2 time(s). Last edit at 06/05/2018 05:04PM by golfox2.

What happens if you de-level the bed downward in the back so it it too low in back. Does it then make the front too close to the bed? Where does it start leveling? Front left? Front Right? Back Left? Back Right?

-os3dp

The cable guide looks pretty rigid. Does the inductive probe tilt, when you are probing at the back of the bed?
Do you still get bad level, when you move the MK3 heated bed elsewhere? It might have some influence on the probe...

Hi, sorry I didn't precise, it probes front-left, then front-right, then back-right, then back-left. 4 points in total.

Quote

Does it then make the front too close to the bed?

It does not change anything, if I de-level, in any way, the printer still compensates, but will do the same problem even with a maximum tilt angle.

Quote

The cable guide looks pretty rigid. Does the inductive probe tilt, when you are probing at the back of the bed?

I thought about that being an issue, I tried without and it was not any better. So I put it back.

Quote

Do you still get bad level, when you move the MK3 heated bed elsewhere?

Indeed that could be something, I'll try it asap, thanks for the idea

Thanks guys, I hope we will be able to solve this

Edited 1 time(s). Last edit at 06/06/2018 05:04AM by golfox2.

Check the glass thickness too, your measuring the bottom and printing on the top, or rotate the glass to see if it changes

The thing I don't understand is that it was working a few weeks ago, and suddenly, stopped working.
In fact, my hot-end fixation just melted after the fan didn't start one time. So I thougt that was the issue, and I replaced the defective parts. But no result.
Yes I also tried to rotate 90, 180, 270° de glass plate, same, no improvement.

Do you guys think something exists to set an offset for each probe point here in the configuration.h of the software ?
I'm in linear auto bed leveling

#if ENABLED(AUTO_BED_LEVELING_LINEAR) || ENABLED(AUTO_BED_LEVELING_BILINEAR)

  // Set the number of grid points per dimension.
  #define GRID_MAX_POINTS_X 2
  #define GRID_MAX_POINTS_Y GRID_MAX_POINTS_X

  // Set the boundaries for probing (where the probe can reach).                
  #define LEFT_PROBE_BED_POSITION 5
  #define RIGHT_PROBE_BED_POSITION 130
  #define FRONT_PROBE_BED_POSITION 15
  #define BACK_PROBE_BED_POSITION 145

That would surely solve the problem I guess

hey, up =)

Do you guys think something exists to set an offset for each probe point here in the configuration.h of the software ?
I'm in linear auto bed leveling