Prusa XL X motor  

RE: Prusa XL X motor

The XL is a Core XY printer so I Believe it uses both motors to cause X and Y movement

one motor alone will drive the extruder at 45 degrees in one direction the other motor, alone will drive the extruder in 45 degrees in the perpendicular direction 

regards joan

RE: Prusa XL X motor

Hi,

Yes that is what I suspected by moving the gantry. What I am really trying to figure out is that when I run the the input shaper cabibration it come back with the Y direction having a freq match but the X direction belt tension is "loose" even though both sides of the XL pass the tuning test at 80HZ using the phone app. Since each belt has a different tension adjustment( Left side /Right Side)  in the front was trying to figure out what tension adjustment should be adjusted when there is a loose X belt. 

RE: Prusa XL X motor

That is a confusing report, maybe someone who has an XL can help.

regards Joan

RE: Prusa XL X motor

I suggest using the Homing Tower to get the right belt tension: https://help.prusa3d.com/article/adjusting-belt-tension-xl_401793

RE: Prusa XL X motor

Just to close this out the Right Side is the Y axis and the Left Side is the X axis when doing the adjustments. (When looking at the XL from the front) You can also verify this by very very  gently touching the different belts when the calibration is be run to feel the vibrations.

RE:

When adjusting the tension screws, it's important to move the gantry to the end positions and retry/check again, until the tension is correct. (the homing tower does exactly this after each layer). I had the best results, when moving the gantry via the steppers instead of pullling/pushing it by hand.

Furthermore, you need to take care that the gantry is in parallel by checking whether both sides touch the end stop in the front position. It's possible to have a correction tension of both belts, while having a misalignment of the gantry. Therefore it's an iterative process until alignment and tension are perfect.

RE: Prusa XL X motor

It's possible to have a correction tension of both belts, while having a misalignment of the gantry. Therefore it's an iterative process until alignment and tension are perfect.

I had this exact issue, so I'd love a detailed guide on the correct way to iterate through it. I somehow stumbled into fixing it without really understanding how.

RE:

Adjusting belt tension (XL) | Prusa Knowledge Base (prusa3d.com)

RE: Prusa XL X motor

The description in the knowledge base is not really detailed in my opinion. To move the gantry push/pull the gantry in its middle. I'd start with the gantry in the front endstop position, adjusting the screws so that the gantry is touching both endstops and both belts have a comparable tension (verification for small gaps can be done by pushing the side of the gantry against its endstop by hand- if there is a slight "bumping noise", then there is a small gap).

Then starting the adjustment process according to the description in the knowledge base (as linked above by Brian) in an iterative way, until everything is perfect:

• Adjusting/checking tension with the screws
• Move the gantry to the back then to the front endstops
• Adjusting/checking alignment of the gantry to the front endstops
• Repeat until perfect

RE: Prusa XL X motor

With the screws you generate force on the belts be adjusting the position of the pulleys (easy spoken along the screws). They should have nearly the same position on both sides, so the routing of both belts is symmetric. In worst case, one pulley is positioned near the end of the screw while the other is positioned near the start of the screw. This leads to asymmetry in the routing of the belts and therefore misaligned gantry.

RE: Prusa XL X motor

In worst case, one pulley is positioned near the end of the screw while the other is positioned near the start of the screw.

Yea I followed the KB, but like you said it is vague. Several attempts always ended up with one end having a gap regardless if I did the alignment step first or not. At some point I tried different things like if the right-side was over-tensioned then I unscrewed the left-side instead of the right, or conversely if right-side was under-tensioned then I tightened the left-side instead of right. And at some point of doing that 'randomly' for a few hours I got rid of the asymmetry. There were several attempts where I just went full slack and started at zero. Maybe that full slack belt realignment helped. I'm really not sure.