4th Axis not rotating, throws errors

[MajorFrantic]

I'm using the recommended UGS to operate the Mega V with a 4th axis.

The axis motor 'activates' when the system powers up (the chuck can no longer be spun by hand), but the motor will not move further under command.

On occasion, when homing the machine, the 4th axis will momentarily turn a few degrees like a twitch of movement. It immediately stops and does not move further.

This is the error that shows up when you try to jog the A axis manually.

>>> $J=G20G91A10F400
[Error] An error was detected while sending '$J=G20G91A10F400': (error:15) Jog target exceeds machine travel. Jog command has been ignored. Streaming has been paused.
Any advice or suggestions from the hive mind?

Thank you.

[MajorFrantic]

A quick update. Big shout-out to Millright's support team for answering emails over a holiday weekend during a pandemic. Remember to take your time for family and breaks, but as a customer I really appreciated the help.

This one was entirely user-error in not understanding the functionality of the axis and how it interacts.

I got instructions to try two different commands.

G0 A300
G0 A-300

The first resulted in the same error I've been seeing.

The second spun the axis 300 degrees.

That's when the 5-watt bulb in my head went on.

I was mistakenly thinking of the 4th axis in terms of a continuous rotation, i.e. being able to exceed 360 of rotation in any direction.

The 4th axis run from -360 to zero on the DRO. It will only make one controlled revolution.

I kept trying to move it in a positive direction, where it had no degrees left to rotate, thus the error.

I hope this helps someone else, who like me is just learning how to think like a CNC programmer.

Thank you,

Jeremy

[Bruce]

Thanks for the post on the A axis operation.

[MajorFrantic]

I may have spoke too soon, Bruce. The second email from support indicated it should be able to rotate much further. However, I can't change the setting they suggested, i.e. $133=5000. It's locked.

We'll see what tomorrow brings in terms of clarity.

Anyone else with a 4th Axis able to chime in on their setting for $133 and what they have experienced with the rotation limits?

[MajorFrantic]

OK. Another learning moment. I was able to make changes to the settings by exporting, editing the text file and then importing back into UGS.

I set the rotation ($133 = 5000) and it does allow greater than 360 degrees of rotation now for the A-axis.

[Bruce]

You should be able to just type in the console: $133=5000 <ENTER>
To change the GRBL setting.

[MajorFrantic]

Apr 15, 2020 22:25:30 GMT Bruce said:

You should be able to just type in the console: $133=5000 <ENTER>
To change the GRBL setting.

That doesn't work for me. I get an error that the settings are locked and to contact Millright.

Support said there was a way to unlock the settings, but didn't provide specifics.

I couldn't find anyway to unlock in the UGS interface or menus, but did get the export/import function to work as a functional workaround.

Jeremy

[Bruce]

Oh, this must be a 4th axis function. Thanks.

[Derek the Admin]

At the top of UGS if you go to tools/options there is a sender settings section where you can unlock those.