Auto_Bed_Leveling: Enhanced G29 command

[Roxy]

G! X5.0 Y5.0 put it in the front left corner.

Between, and Before Probings is at 4 and 4.

So you need to activate the #define for the FRONT LEFT corner! And then see what the Topology report says. You should be able to get things very close to level if you correct the worst corner each time you run it. And when things are little be more flat, doing it with a 4x4 grid will help you see if you have high and/or low spots on the bed.


But your corners are not crazy. It should print well the way it is.

[DarkAlchemist]

If I touch anything on that bed it gets very bad very quickly and I do believe I changed that to front left the last time I was in the configuration file as I issue G29 and it heads straight for that corner.

I tried for 2 weeks solid (16 hour days some times) with a dial indicator and could not level this bed. I can get the corners level to 0-3 (.01mm per) from middle but then the rest of the bed is really non flat and bad off (7-10).

[Roxy]

Can you post a 4x4 Topographical map of the bed? Let's see if we can see any 'unflatness'.

[DarkAlchemist]

I can do better than that I will go do an 8x8 which is what I was going to do in a few minutes anyway.

[DarkAlchemist]

>>> g28
SENDING:G28
>>> g29 u 8 T
SENDING:G29 U 8 T
Eqn coefficients: a: 0.00 b: 0.00 d: -4.06
Correct +.14 with one clockwise turn.

Bed Height Topography:
+0.00700 +0.05450 +0.09825 +0.12150 +0.14600 +0.15850 +0.16950 +0.18225
--0.02250 +0.03025 +0.06875 +0.10050 +0.12275 +0.13725 +0.16725 +0.16675
--0.05775 --0.00625 +0.04000 +0.07225 +0.10050 +0.11675 +0.13250 +0.15175
--0.10150 --0.04550 +0.00150 +0.04150 +0.07225 +0.09200 +0.10475 +0.12800
--0.15650 --0.09350 --0.04175 +0.00125 +0.03350 +0.05725 +0.07625 +0.10100
--0.21700 --0.15300 --0.10300 --0.05575 --0.01525 +0.01175 +0.03650 +0.07125
--0.26400 --0.20600 --0.15300 --0.11000 --0.07100 --0.04200 --0.01750 +0.01325
--0.31425 --0.24575 --0.20825 --0.16475 --0.12725 --0.09075 --0.06800 --0.03500

planeNormal x: -0.00 y: -0.00 z: 1.00

Bed Level Correction Matrix:
0.999999 0.000000 0.001433
0.000000 0.999998 0.001805
-0.001433 -0.001805 0.999997
echo:endstops hit: Z:-3.61

That looks flat to me (thanks to the boro glass I bought).

[Roxy]

Yes! That does look flat. Did you set the number of points for Auto Leveling at 8? I'm not sure there is enough stack space to have that much local storage. I've never pushed it to see where the limit is. But it does appear that the values are fine and the code ran to completion!

[DarkAlchemist]

Yes! That does look flat. Did you set the number of points for Auto Leveling at 8? I'm not sure there is enough stack space to have that much local storage. I've never pushed it to see where the limit is. But it does appear that the values are fine and the code ran to completion!

Yes, it is at 8 for now.

I still want to know how I can tweak X and Y to be sure the probe really is blah blah mm away AND I don't understand what this "Correct +.14 with one clockwise turn." is telling me?

[Roxy]

That 'Correct +.14mm' is for me... I should have deleted that when I crossed your configuration information over to my code base. That is so I don't have to think. If I have a corner that is +.14mm too high, I need 1 turn of the screw to lower it that much.

Can you explain in more detail what you want to tweak on the X & Y? Are you trying to set the X & Y Probe offsets from the Nozzle?

[DarkAlchemist]

Yes, I tried to eyeball it as best as I can but I know I am not 100% spot on accurate but would like to tweak it to be.

[Roxy]

Yes, I tried to eyeball it as best as I can but I know I am not 100% spot on accurate but would like to tweak it to be.

Well, the good news is the X & Y Offsets to the nozzle don't have to be perfectly exact. This is a simple function of the fact the bed is fairly flat to start with. So however much the Z-Axis needs to be compensated as you move around on the bed, the X & Y correction is very very small. Maybe somebody else can jump in here, but mathematically the sin(theta) approaches 0.00 as theta approaches 0.00 And the angle of your bed is less than .5 degrees out of kilter going kitty corner. Just holding a ruler up to the center of the nozzle and where the switch is going to get pressed in both the X & Y direction is going to work fine. And actually... If I remember right, those offsets are used to correct the Z height, not the X & Y. The reason is, where the probe measured is different than where the nozzle is, so it corrects the nozzle height based on how far away in the X & Y the probe is.

If it is working well... More accuracy on the X & Y offset won't help.