BLTouch - Help Needed

[Alessio3d]

Hello everyone
a few months ago i bought a BLTouch sensor ,installed it and flashed the new firmware to enable it (Marlin 1.1.9) without having big problems.
From firmware I enabled the auto bed leveling function in linear mode specifying that 9 points of the plan must be tested; I also set the various x y and z offsets between the nozzle and the probe.
Made a few small prints (about 5 centimeters wide) adding G28 and G29 to the start G-code and had no issues, the z axis was moving while printing to compensate for the not perfectly level surface

Today I tried to print an object with a much larger surface and the problems started here:
during the printing of the first layer, it was clearly visible that the thickness was different between the various areas of the printing plate,
in some areas the nozzle was too close to the glass, preventing the right amount of filament from coming out while in other areas the quantity of filament was perfect.
To make sure it wasn't a random problem, I re-launched the same print 3 times, always getting the same result, so I decided to change the firmware settings by increasing the calibration points from 9 to 16, carrying out 3 tests for each point of calibration and calculating the average value, also I also added a small delay at the beginning of the test at each point as recommended on some forums.
I then launched the print again and got the same result

What am i doing wrong?
Any help?

Regards

Alessio

[e415ldc]

I would suggest using Bi-Linear instead of Linear. No real reason other than this is what was suggested in Marlin for 2.0.x. I have been using Bi-Linear for a few years without issue. Also I use the suggested three points by 3 points grid and sample twice on each. I have had success with first layers as thin as .2mm and as thick as .5mm using .2mm nozzle for the .2mm layer and .5mm nozzle for the .5mm layer.

I have also swapped my glass build plate for an aluminum one with a magnetic build surface to allow for easier part removal with the thinner first layers. Materials I've had success with are PLA, ABS, PETG and TPU.

Good luck.

[Alessio3d]

Thanks for the tip, I set the bilinear mode and so I solved my problem

Regards

Alessio

[LoBoHEAT]

Hi,

it´s impossible for me open a new thread for ask about the autolevel, readings the installation instructiosn says:

Step1. Remove the Z max connector from the board and replace it with a 3Pin Straight Pin. You need to use soldering iron here.

I see in my control board 3 pins besides the Thermistor extruder 1 connector, and I see in some wiring diagrams that they are for connect the sensor, but I don´t know how to connect it.

Best regards.
Javier.