Mesh bed and bltouch

bartolomeus

If you are getting different results every time, I can see two likely causes:

1. Your bltouch is not triggering at a consistent height.

2. Your motion system is not repositioning the probe at a consistent position and height.

Here is a script (my thanks to Russ Gries for it) to test the reproducibility of the probe trigger height, by probing the same point 32 times:
; Probe testing single point. 
G30 P0 X0 Y0 Z-99999 F2000 
G30 P1 X0 Y0 Z-99999 F2000 
G30 P2 X0 Y0 Z-99999 F2000 
G30 P3 X0 Y0 Z-99999 F2000 
G30 P4 X0 Y0 Z-99999 F2000
G30 P5 X0 Y0 Z-99999 F2000 
G30 P6 X0 Y0 Z-99999 F2000 
G30 P7 X0 Y0 Z-99999 F2000 
G30 P8 X0 Y0 Z-99999 F2000 
G30 P9 X0 Y0 Z-99999 F2000
G30 P10 X0 Y0 Z-99999 F2000 
G30 P11 X0 Y0 Z-99999 F2000 
G30 P12 X0 Y0 Z-99999 F2000 
G30 P13 X0 Y0 Z-99999 F2000 
G30 P14 X0 Y0 Z-99999 F2000
G30 P15 X0 Y0 Z-99999 F2000 
G30 P16 X0 Y0 Z-99999 F2000 
G30 P17 X0 Y0 Z-99999 F2000 
G30 P18 X0 Y0 Z-99999 F2000 
G30 P19 X0 Y0 Z-99999 F2000
G30 P20 X0 Y0 Z-99999 F2000 
G30 P21 X0 Y0 Z-99999 F2000 
G30 P22 X0 Y0 Z-99999 F2000 
G30 P23 X0 Y0 Z-99999 F2000 
G30 P24 X0 Y0 Z-99999 F2000
G30 P25 X0 Y0 Z-99999 F2000 
G30 P26 X0 Y0 Z-99999 F2000 
G30 P27 X0 Y0 Z-99999 F2000 
G30 P28 X0 Y0 Z-99999 F2000 
G30 P29 X0 Y0 Z-99999 F2000
G30 P30 X0 Y0 Z-99999 F2000 
G30 P31 X0 Y0 Z-99999 F2000 S-1
Save it as a macro and run it. If X0 Y0 is not a good point to probe on your printer, change those coordinates in every line to something that is.

F2000 is the speed right? Isn't that too fast for the bltouch?

I have found that if you want to run G29 consecutively, for the next run you should first Disable Bed Compensation and then re-home Z. Else, you will get different results.

dc42

I don't know the BLTouch, but i agree, F2000 is rather high. Try 300 or 600.

gideon

Hello i will try F3 a 600. Towmorrow. Thanks for the advise

gideon

Hey,
I ran the macro,
see here what came out
F300
G32 bed probe heights: -0.007 -0.002 0.000 -0.020 -0.010 0.010 0.007 0.007 0.010 0.010 -0.007 -0.012 -0.007 -0.012 -0.007 -0.002 -0.007 -0.012 -0.010 -0.010 -0.010 -0.012 -0.012 -0.015 -0.002 -0.020 -0.025 0.002 -0.007 0.002 0.042 0.023, mean -0.004, devi
I do not think this is all right, I see the same value a number of times but also many different ones
does anyone have an idea where it can be,

F100
M98 P0:/macros/test
G32 bed probe heights: -0.060 -0.035 -0.032 -0.062 -0.032 -0.040 -0.037 -0.047 -0.037 -0.062 -0.040 -0.030 -0.060 -0.055 -0.045 -0.067 -0.045 -0.060 -0.062 -0.060 -0.060 -0.062 -0.065 -0.060 -0.060 -0.070 -0.050 -0.060 -0.055 -0.060 -0.053 -0.037, mean -0

bartolomeus

Here's mine with:
F100:
G32 bed probe heights: 0.038 0.041 0.042 0.048 0.040 0.043 0.039 0.040 0.040 0.038 0.043 0.040 0.039 0.033 0.036 0.016 0.033 0.040 0.041 0.041 0.041 0.041 0.042 0.038 0.040 0.048 0.043 0.040 0.039 0.046 0.039 0.042, mean 0.040, deviation from mean 0.005

F150:
G32 bed probe heights: 0.039 0.041 0.044 0.043 0.038 0.039 0.040 0.041 0.040 0.042 0.042 0.040 0.040 0.044 0.038 0.043 0.044 0.038 0.041 0.045 0.048 0.042 0.039 0.041 0.044 0.043 0.044 0.043 0.046 0.044 0.044 0.039, mean 0.042, deviation from mean 0.003

I also did some testing with higher F values, however, as my Z speed wax maxed at 200mm/min, the higher F values were also maxed at 200mm/min and not being used.

dc42

@gideon, it looks like your bltouch (or clone) isn't giving reproducible results. Some other users have reported this problem too.

gideon

with you the differences are less great than with me I see,
I am thinking about testing one with the ininductive sensor
see what it does,
whether the differences are still so great

whosrdaddy

@gideon:

with you the differences are less great than with me I see,
I am thinking about testing one with the ininductive sensor
see what it does,
whether the differences are still so great

if you want accurate, repeatable probing, just use a piezo sensor, I can assure you, I tried all other options, but nothing beats its performance and ease of use (not even close).
https://www.precisionpiezo.co.uk/

gideon

@dc42 Hey,
I am now going to try to see a proximity sensor to see if it works better,
if not, I will order the ir probe

totalitarian

The BLtouch should be more than accurate enough. Of course, it depends how rigidly you have mounted it. Another good test it to check how mechanically sound your machine is. Set your height a sheet of paper using the nozzle, raise and lower the head by 5mm, check if you still get the same gap between the bed with the paper;.

gideon

I have now even mounted a proximity sensor, I think this is better. or is it still nothing
M98 P0: / macros / test
G32 bed probe heights: -0,600 -0,600 -0,600 -0,602 -0,602 -0,608 -0,605 -0,605 -0,602 -0,602 -0,602 -0,605 -0,600-0,602 -0,605 -0,605 -0,605 -0,605 -0,608 -0,600-0,600 -0,602 - 0.605 -0.608 -0.608 -0.605 -0.605 -0.608 -0.605 -0.602 -0.605 -0.605, mean -0

bartolomeus

That looks a lot better.

I just re-run one of my tests with the bltouch, as probing at higher speeds made no sense as my z speed in config.g was limiting the probing speed. So I now set my Z speed and probe speed to 250. This was the result:

G32 bed probe heights: -0.001 0.003 0.003 0.007 0.001 0.005 0.002 0.006 0.003 0.004 -0.001 -0.004 0.001 0.004 0.003 0.001 0.001 0.005 0.005 0.003 0.004 0.006 0.007 0.009 0.000 0.009 0.003 0.003 0.009 0.003 0.003 0.001, mean 0.003, deviation from mean 0.00

gideon

12:06:43M98 P0:/macros/test white F100
G32 bed probe heights: -0.205 -0.200 -0.200 -0.200 -0.203 -0.203 -0.203 -0.200 -0.200 -0.198 -0.200 -0.198 -0.200 -0.200 -0.203 -0.203 -0.200 -0.198 -0.203 -0.200 -0.200 -0.200 -0.205 -0.200 -0.203 -0.200 -0.200 -0.203 -0.200 -0.200 -0.200 -0.200, mean -0