Hello,

First of all, thanks for the answers I understood more in these two days than in a month of homemade research.

Let's start with order:

I counted the teeth on the motor pulley (X & Y axis) and is 15 teeth

On the engine pulleys there are two grubscrews and two "footprints" on the shaft, so as to make everything more stable.

As for the pulleys on the threaded bars the nuts and lock nuts that hold everything are stopped with the threadlocker (like the loctite) and also here they should not go anywhere.

As for precision as a first mention the project was bought so I'm pretty sure it should go (unless of my assembly errors)

There is also a video that shows how it works on youtube, and as I said its author is mentioned a couple of times in this forum or Mirko slepko ...

Tomorrow I will try to set the values for the Z axis in order to verify the behavior ...