@mrehorstdmd said in Cannot for the life of me figure out how to use M556:

The belts look pretty close to parallel to me, but the print looks over extruded, but closer look finds gaps between every other solid fill line. It looks like the extruder lays down a line, then doesn't shift far enough when it comes back along that line creating excessive overlap and then it moves over to lay down the next line and that leaves a gap. That implies some backlash in the mechanism. Are the belts tight and approximately equal in tension?

The extruder carriage looks pretty narrow- is there any play in the carriage -does it wiggle on the guide rails? Grab the hot-end and try to wiggle it. Check for play in the Y axis bearings, too. Nothing should wiggle.

Thanks! I think I might have found it, there was wiggle in the Y idlers. The x carriage, even though it’s tiny, is quite stiff so I think it’s fine.

That should explain the over/underextrusion on the model.

@dc42 said in Cannot for the life of me figure out how to use M556:

It may be because of the camera angle, but section of the belt at top left of the first image between the stepper motor and the Y carriage looks like it may not be parallel to the rod.

Hmm, I’m not sure either. I took everything apart to fix the y idlers which had a bit of wiggle in them. I’ll be careful for that when I re assemble.

Thanks for all the replies!

@mrehorstdmd I’ve attached a pic of my mechanism. The belts seem to be parallel. However, I haven’t tried printing my circle test model at different points on the bed to see how positioning, and therefore different belt tension in places would affect them.

It’s in a rougher shape now as I’m troubleshooting.

Below I’ve also attached a pic of the circles.

@dc42 thanks! I’ll dive deeper, the first quick search I did didn’t seem to bring anything up.

Hi everyone,

Long story short I’m struggling with not having perfect circles on a home made CoreXY machine. I’ve tried everything, and now the bots are tight and equal, the motion of the carriages on the smooth rods are super smooth, accelerations and jerk settings are very low so the only thing left to do in my head is square the frame.

Unfortunately that is not a solution at the moment and I wanted to use orthogonal axis compensation.

I have no idea how it works. I printed the parts and have the S parameter, but how do I get the x y z Paramus. I cannot find a single forum post or article on the internet explaining this and the old guide from reprappro is no more. My values are large like 6.3 my vs the 0.7mm I see floating around.

Thanks for the reply!

I don't quite understand what G31 S-2 does. Looking at the wiki the S parameter is for temperature calibration?

I'm going to try it out anyway and see the results.

Regards,
Adrian

Hello everyone,

I'm trying to set up a semi-automatic probe offset Macro for my self built CoreXY printer.

Essentially, the process is to home, send a G30 command to probe the bed. After that I zero the height with G92 Z0 and send M208 S1 Z-100 so I can use the jog controls to go below 0.

I then use a piece of paper to find the correct nozzle height and then I put that Z height (changing its sign from - to +) in the G31 command in the config.

However, I do not know how I can automate this.

1st Macro will look like this:

"
G28 X
G28 Y
G1 X110 Y110 F6000
G30
G92 Z0
M208 S1 Z-100
"
I would then to the paper thing and I want another Macro to read the Z height value and save it in the config. Is there any way I can do this?

Macro 2:
"
G31 Z"M114 Z"
M500
"

Regards,
Adrian