Changing 4th Axis rotation direction?

[Dylan]

Does anyone know if it's possible to change the direction that the 4th Axis rotates?  Here's why I ask; I've mounted my 4th (A) axis in alignment with the Y axis with the stepper motor/chuck assembly on the negative/front side of the table.  I'm in the midst of milling out a 4-sided project, the gcode for which was generated in DeskProto.  The problem is that the A Axis is rotating counterclockwise when it should be clockwise.  I'd noticed this when jogging the A axis in UGS even before starting to cut my current project.  I've looked in both UGS and DeskProto for a setting to flip the A axis rotation but haven't found anything.  I'd like to avoid having to place the 4th axis chuck on the other side of the table, if possible, because of the inconvenience of being able to reach it.

I'm using UGS 2.0.14 and DeskProto 7.1

Any help would be appreciated.
Dylan

[bLouChip]

Yes, A axis direction of rotation can be reversed.  I do this for the same reason.

$$ command will display the grbl configuration. $3 is the axis direction register for all axes. Its a decimal value representing a binary value. To reverse direction of A axis, simply add 8 to your current value of $3, which is likely the decimal value 2, which reverses the Y axis. If that is the case, then adding 8 + 2 = 10.  Issue command $3=10.  It should be immediately affective, but to be safe, disconnect and connect UGS, and rehome the machine.

more info here: github.com/gnea/grbl/wiki/Grbl-v1.1-Configuration#3--direction-port-invert-mask

The A axis is not shown in this link because its config help for 3 axis machine, but A axis is the next bit to the left after Z, hence the decimal value 8.

[Dylan]

Thanks for the info! I'll give it a try in the morning. I knew there had to be a setting or something in one of the softwares that could do it, I just didn't know where or how.

[Dylan]

That did the trick. So easy and simple when you know what to do. Thanks for the help.