M453 Issue after homing

Ryan Lock

It also affects the Z-Axis. And stops homing of individual axis for the X and Z. For example:

G91 ; relative positioning
G1 S1 Z94 F1500 ; move quickly to Z axis endstop and stop there (first pass)
G1 Z-3 F2400 ; go back a few mm
G1 S1 Z94 F300 ; move slowly to X axis endstop once more (second pass)
G90 ; absolute positioning

Gives an outside machine limits error. Same for the X-Axis. But on the Y-Axis it works, even though it is the same code, except Z replaced with Y.

Ryan

dc42

I'm sorry for the delay in responding, it's been very hectic here with multiple deadlines to meet. I will look into this on Saturday.

dc42

@Ryan-Lock, please post your config.g file so that I can try to reproduce this.

Ryan Lock

Hi David,

Please see attached. I have also attached our homeall file.

Best Regards

Ryan Lock

1_1552643858526_config.g 0_1552643858525_homeall.g

dc42

Thanks. I've reproduced the problem, although with 2.03beta I don't get the out-of-limit message, it just refuses to jog X and Z (in the negative direction) until I jog Y. I'll fix this tomorrow. My guess is that the fix I put in beta 2 wasn't quite right.

Ryan Lock

Hi David

Not a problem. Yes i did notice it didn't display the error but refused to move. But if i remember correctly switching back to the original web control it showed the error. So i presumed that was a bug in the new gui.

A fix would be great.

Best Regards

Ryan Lock

dc42

Hi Ryan,

I have located the problem. Your Y steps/mm is an unusual value, and as a result the Y axis limit of 520mm does not round-trip to motor positions and back again exactly. This results in the user Y position after homing being very slightly greater than 520, although you can't see that because the value is rounded to 1 decimal place for display.

To fix this, I propose to allow commanded positions to exceed the axis limits by 0.05mm. Do you consider this acceptable?

Meanwhile, a workaround is to add either G1 Y520 or G92 Y520 in your homeall.g and homey.g files after the Y axis has been homed.

dc42

PS - is your Y steps/mm exactly 53 and 1/3 mm? If so then there is a simpler workaround: change the Y steps/mm from 53.33 to 53.33333 . With this value, the rounding error does not occur.

Ryan Lock

Hi David,

Sorry for the late response on this.

Yes it is 53 1/3 exactly.

Changing it to 53.333333 did allow movement from the homed position on all axis. However when getting to the other end of the travel, you could never get to your absolute minimum on the axis with 53.333333.

So putting the G92 command in the homing files is the best solution to this.

Best Regards

Ryan Lock

dc42

Ryan, please try firmware 2.03beta3 which I released recently. it implements the additional tolerance that I mentioned in an earlier reply.