Gantry movement problem

[Steve_K2400]

Hi!
I hope you don't mind if I ask my question here. I'm hoping to leverage the expertise of your community regarding CoreXY printers.
I'm not new to 3D printing but absolutely new to CoreXY printers so, I have some problems troubleshooting my build.
I'm building a Proforge 4.2 which is as I know based on a Voron design.
I'm not able to find the problem why my gantry is moving so abruptly (and banging loud) when changing direction on the Y axis.
You can see it in this video.

I checked my X rails, they are completely parallel. The Y rail has right angle to the X rails.
The rails are not 100% super smooth but without the belt the gantry moves smoothly and evenly.
I tensioned the belts the best I could.
The Proforge has 4 motors for the XY movement. (2 for each direction.)
Could there be a problem with synchronization?
I would be happy to hear any advice.
Thanks.
Steve

 

[Steve_K2400]

Just as an info: in the meantime (the approval of my first post took some days) I got some tips in another forum: properly retighten my belts and synchronize the 4 motors.
I'm waiting for a belt tension gauge to arrive, then I will try to do those things.

 

[NoGuru]

I can't see the video at work but I have a 4 motor Voron 2.4.
Syncing the motors should be done but not 100% critical. There is two ways to do this, one is mechanical and the other logical. Lookup Vez3D on youtube and find his video for syncing motors.
On top of that I use a motor sync macro you can find here https://github.com/MRX8024/motors-sync

And the last suggestion would be make sure the motors are all working together by going though the startup here and the Stepper motor checks.

Initial Startup

Voron Official and Community Documentation

docs.vorondesign.com