Machine Home Readout in UGS

[tazman]

All,
Let me start out by saying that I have completed the assy of my Mega V and it works good so far.  I initiated a homing cycle and it worked as planned with one exception.  The readout after it finish's the homing cycle for the machine zero is correct at -5.00 in Y and Z, but the X shows a large number like -895.00 I thought it should read -5.00 like the other two axis's. Am I missing something?  It did go into the switch first, back off, and go back in slowly and then come back out like it should.  I did the G28.1 command but I do not feel this has anything to do with it.  Thank you in advance.

[btreichel]

from wat I know its all relative, however 895 mm is about the size of the 35 x 35 V. Baxk the axis off a couple of inches, and run home again.

[Bruce]

Make sure you know the difference between the Machine Position and Work Position. After you run the home routine the Machine position should be -5mm on each axis or whatever the pull off value is set to after hitting the limit switch. The Work Position could be any number until you set it for your workpiece zero point.

$H - Run homing cycle
This command is the only way to perform the homing cycle in Grbl. Some other motion controllers designate a special G-code command to run a homing cycle, but this is incorrect according to the G-code standards. Homing is a completely separate command handled by the controller.

TIP: After running a homing cycle, rather jogging manually all the time to a position in the middle of your workspace volume. You can set a G28 or G30 pre-defined position to be your post-homing position, closer to where you'll be machining. To set these, you'll first need to jog your machine to where you would want it to move to after homing. Type G28.1 (or G30.1) to have Grbl store that position. So then after '$H' homing, you could just enter 'G28' (or 'G30') and it'll move there auto-magically. In general, I would just move the XY axis to the center and leave the Z-axis up. This ensures that there isn't a chance the tool in the spindle will interfere and that it doesn't catch on anything.

[tazman]

Thanks Bruce. I have tried the $H command and it does the same thing. I do have experience with CNC machining and would have suggested the difference between home and work position as well. I may have to hit up UGS to see if I can find anything to help with this issue. I am wondering if anyone else running a Mill Right CNC has had this issue come up. May have to contact Derik about this. I appreciate your feed back and have found your other posts insightful and useful as well. Thanks again for taking the time to respond.

[garymkrieg]

You could also install Open Builds Control and try that instead of UGS, to see if you get the same results.

[tazman]

I might just have to do that.

Thanks,

[tazman]

Gary,
I tried the Open Builds Control and it showed the same thing. So either it is something in the controller not set right or I have something not right when I plugged everything in. The machine homes like it should, and travels in the correct directions so I do not think this is the issue.

Thanks again,

[Bruce]

Are you sure the X axis limit switch is working? Do you see a green LED light up on the MillRight breakout terminal board when you trigger the limit switch?

[tazman]

Bruce,
Yes it is working. I received an email back from support at Mill Right and was told that this is correct / normal. I will post the complete response later for archival purposes incase someone else has the same issue. I am surprised no one else has asked this before with all of the Mega V routers out there.

[tazman]

Jun 23, 2020 22:42:41 GMT tazman said:

All,
Let me start out by saying that I have completed the assy of my Mega V and it works good so far.  I initiated a homing cycle and it worked as planned with one exception.  The readout after it finish's the homing cycle for the machine zero is correct at -5.00 in Y and Z, but the X shows a large number like -895.00 I thought it should read -5.00 like the other two axis's. Am I missing something?  It did go into the switch first, back off, and go back in slowly and then come back out like it should.  I did the G28.1 command but I do not feel this has anything to do with it.  Thank you in advance.

As promised, below is the quick response that I received from Mill Right Support.  It makes sense to me now.

"This is because the readout is displaying the homing pull off cycle plus the programmed limit value. The X axis is homing to the low side of travel whereas the Y and Z home to the high side. It is indeed normal. Machine coordinates matter very little. It's all about your work coordinate anyway."

Thanks to all for your help and to Mill Right Support.  Happy milling!!!