Struggling with X & Y motion in my Duet-powered CoreXY [SOLVED]

I'm getting close to completing my new CoreXY printer (G&C Printer) and this morning powered it up for the first time.

All seems fine apart from the X and Y motion, which is giving me a headache. No matter what I do with the M569 commands in the Duet's config.g file, I can't get them to move properly. Here are the relevant lines in the config.g file:

; Movement section

M569 P0 S0							; Drive 0 goes forwards
M569 P1 S1							; Drive 1 goes forwards
M569 P2 S1							; Drive 2 goes forwards
M569 P3 S1							; Drive 3 goes forwards
M569 P4 S1							; Drive 4 goes forwards

Ignore all the bits about "Drive n goes forwards" - I'll retype those when it works.

In this current configuration, the carriage will move correctly in the Y axis, but the X axis is reversed. Changing the M569 instruction to fix this is not so simple, as in CoreXY both motors work together to move in a straight line in either axis. This means that changing the direction of 1 motor just changes the error. I've tried reading all the documentation about M569, but that's not particularly helpful when considering CoreXY. I've had to assume that P0 is the X motor, and P1 the Y motor. P2 seems to affect the Z motor, and that's working properly.

I've looked at Filipe's (the designer's) config.g file, and that's only slightly different - he had P0 S1 and P1 S0, but that just changed the error around for me. The result was that the carriage moved correctly in the X axis, but was reversed in the Y. I've also tried P0 S0/P1 S0 and P0 S1/P1 S1, but that just made it worse.

Maybe the CoreXY code needs "reverse X axis" and "reverse Y axis" commands! (or maybe these already exist and I've missed them in the G code lists)

Can anyone offer some guidance in the meantime?

Edited 1 time(s). Last edit at 11/07/2015 02:25PM by David J.

Does reversing the wiring to one of the motors fix it?

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

Hi,

The configuration for me was very easy and straightforward, you must have something wrong you are not looking at.

It appears only the x movement is not correct. But you need to consider there is not an correct direction. The correct direction depend where is your 0 point and the 0 point is defined by the endstops.
Have you checked if the configuration of your min endstop is correct? I think if you change the x endstop position to max or vice verse will solve this.

you can to checked if the motor x and y cable are correctly installed in the board, can you send an photo of the motor cables connected to the board?

digital_dentist - I shouldn't have to play with the motor wiring, as the M569 command should be able to reverse each motor from the config file (and it does). The connectors are polarised anyway, so reversing the connection is deliberately not easy!

filipe - where do you have your X = 0, Y = 0 point on your machine? I'm working on the assumption that the 0,0 point is front-left of the bed, when looking at the front of the machine. The Duet is wired according to this diagram, with the X motor being the motor on the left as you look from the front. The diagram doesn't show the X end-stop, which is plugged in to the right of the X motor.



I'll recheck the wiring, and also my config file, in case there's something I missed.

Quote
David J
In this current configuration, the carriage will move correctly in the Y axis, but the X axis is reversed.

I had this problem, only with the axis swapped: i.e. X was moving fine but Y was moving in the wrong direction.
The only way I managed to fix it was to invert the Y axis scale like so:

M667 S1 Y-1.0

I hope this works for you (obviously by using X instead of Y).

Hey - that looks interesting. I'll give it a try this evening.

From [reprap.org]:

Quote

The X motor moves the head in the +X and +Y directions when it runs forwards. The Y motor moves the head in the -X and +Y directions when it runs forwards.

I think you need to swap the X and Y motor connections (with the power off!), then play with the S values on the M569 P0 and M569 P1 commands to get the right motion. You can send the M569 commands from the gcode console on the web interface, no need to restart the printer each time you change them.

Edited 1 time(s). Last edit at 11/07/2015 11:11AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Sorted in the G&C Printer thread - David was correct!

Thread closed...

Hey David,

What was the solution? I'm running into the exact same problem!

What David (dc42) said above - I had the X and Y motors swapped. It's not obvious in a CoreXY printer... it's a shame they're called "X" and "Y" as their action doesn't really match their name.

In corexy they are more commonly referred to as A and B motors (see [corexy.com]), or alpha and beta (if you use a Smoothieboard). The motor drivers on the controller boards are usually referred to by, and sometimes labeled as X, Y, and Z because conventional Cartesian type printers are the most common, hence the confusion.

Edited 1 time(s). Last edit at 01/08/2017 09:01AM by the_digital_dentist.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

The problem comes when you have to decide whether the 'A' motor is plugged into the 'X' or 'Y' socket on the controller board, and whether the 'B' motor goes into the 'Y' or 'X' socket.

It's even worse with deltas!