Manual calibration on official website different with manual calibration on printer

[JJ3D 1]

On the official website, it says:

Fine-tuning
"In the next step, fine-tune the position of the build plate using the calibration card. Follow the instructions on the display:

Adjust the thumb wheel underneath the build plate at the back until you feel slight friction when moving the card."

However, on the Ultimaker 3, the first step under fine-tuning instructs you to rotate the button at the front, similar to the first step in rough leveling. Then it asks you to roll and adjust the thumb wheel underneath at the left and right positions not any word about wheel underneath on the back build plate. This seems inconsistent or incorrect.

Does anyone know the correct steps?

Edited November 18 by JJ3D

[ahoeben 2,011]

The idea is to first do a rough leveling with all three screws, and then do another pass with the same screws to do finetuning. If your bed is very unleveled, and you start to fine-tune one screw, going to the next screw will affect the finetuning you did on the first screw. By doing a rough pass over each screw first you mitigate that issue, but it can be worth it to do multiple finetuning passes with each screw in turn.

[CarloK2 9]

Both methods work, but there is a problem with the thumb wheel underneath the buildplate at the rear of the machine. When you repeat the procedure with that rear screw multiple times, then after each procedure, the build plate will rise a little bit further. There is no step in the procedure for tightening the rear screw. Eventually, the back of the build plate will rise so far that it either puts stress on the electric wires to the build plate, or it moves the build plate outside the allowed tension range for automatic bed levelling (40mm if I remember correctly).

 

I remember we changed the procedure to use the front knob instead of the rear screw, but it looks like this was not updated everywere (or the knowledge got lost).

 

So, choose the method that suits you best, but when using the rear screw make sure to add a first step where you tighten it a bit.