Update: 02/08/2019 - use the updated files. they work fine. !
I also added the x end stop and Y endstop! enjoy :-)
The x-axis sits on the 2020 profile with the mini v wheels. when I mounted the original I had a lot of play 3- 4 mm.
So to solve this issue, I enlarged the x-front and x-back parts so that the bottom rollers can be adjusted to the desired tension with the 2020 profile. Doing so the x front and x back will be spaced out. To counter correct this the slot was shortened so that the x-axis front and back are closer to the profile.
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Biqu 3D PLA