Tuning my Core XY

[Brandoan]

I have a really great CORE XY build but it is just a little bit off on this calibration cube. What do I adjust to get this dialed in. One of my axis is dead on 30mm and the opposing axis is off. Do I need to adjust the steps per mm of my core xy motors ? I have tried adjust extrusion and scale compensation but it appears to be an issue specifically with just one of the axis. Any light anyone can shed on how to deal with this would be great! Belts were recently balanced. Machine prints great but I am thinking I need to address this differential in the Firmware.

Best,

Brandoan

[Cristian Nicola]

did you do the extrusion calibration? 

https://github.com/mzbotreprap/VORON/wiki/Slicer---Extrusion-Multiplier-Calibration

also late marlin has skew correction (not sure how / if it works).

Chris

[Brandoan]

Yes the extrusion is accurate.

Your advice is to compensate in firmware and not that I need to do anything physical? That's I guess where my question really lies, it sounds like I can address this issue either way? Does anyone know what method I should use? Are there any downsides to correcting this issue in the firmware?

Best,

-B

[Cristian Nicola]

Ideally you would do it in the hardware. I assumed you already checked if the printer is square and that the belt tension is the same - these are the first 2 things i would try.

For belt tension i would go with something like: https://www.thingiverse.com/thing:2230598

Chris

[Brandoan]

If my small calibration cube is showing .25 mm off on one of the axis isn't it safe to say my hardware is not perfectly square? So shouldn't I be looking there for a fix first before compensating in firmware?

If my system isn't perfectly square then how do I detect what to adjust. My first impulse is to loosen the locking screws on my two x rods and adjust the belt tension slightly. But do I loosen the rods on just one of the gantry's they lock into and then adjust the belt tension or all of them, seems like I need to identify whether my A or B motor in my Core XY setup is responsible for the inaccurate axis and address that one?

Any definitive answers on this?

-B

[Johan Jakobsson]

If the printed parts are square your printer/frame should be square. If their dimensions are off that should be another issue imho.

For Movements along X/Y both motors are moving while one motor move and one stays fixed when moving the printhead at a 45 degree angle to X or Y. Therefore i'd try printing a big square - 50*50mm or bigger - at a 45 degree angle to the X/Y axis to identify which of the motors (/belts/pulleys) are causing the issue.