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Mach Discussion => General Mach Discussion => Topic started by: tjb1 on June 23, 2018, 07:07:19 PM

Title: Z Axis Machine Coordinates Not Changing
Post by: tjb1 on June 23, 2018, 07:07:19 PM
I've started setup on my table and have shared homing working on X, Y, and Z but after doing "Ref All Home" and moving the Z axis machine coordinate number on diagnostics always stays at 0 while X and Y will update when being jogged.  What is my issue that Z doesn't change? Also, is there a way to set work coordinates to 0 when the machine homes?
Title: Re: Z Axis Machine Coordinates Not Changing
Post by: joeaverage on June 23, 2018, 08:01:25 PM
Hi,
that sounds unusual.

When the machine homes each axis LED should go from red to green as it is referenced. Does the Z axis LED do so?
The next question is about the Z axis home switch. If you manually flick the switch does the LED for the Z axis (M3Home for example)
show up in the Diagnostics page? When the Z axis is homed the machine should drive until the Z axis switch operates and then back up a little until
it de-operates. Is this what happens? I'm wondering if the home switch does not deactivate then the Z axis may be permanently and repeatedly being
referenced to zero because the home switch is still active.

Craig
Title: Re: Z Axis Machine Coordinates Not Changing
Post by: tjb1 on June 23, 2018, 08:04:33 PM
Hi,
that sounds unusual.

When the machine homes each axis LED should go from red to green as it is referenced. Does the Z axis LED do so?
The next question is about the Z axis home switch. If you manually flick the switch does the LED for the Z axis (M3Home for example)
show up in the Diagnostics page? When the Z axis is homed the machine should drive until the Z axis switch operates and then back up a little until
it de-operates. Is this what happens? I'm wondering if the home switch does not deactivate then the Z axis may be permanently and repeatedly being
referenced to zero because the home switch is still active.

Craig

If I press "Ref Z", the light turns red, Z axis moves up until M3 is triggered, backs off, and then light turns green.  After that I have no inputs active and when jogging Z, only "Current Position" updates.
Title: Re: Z Axis Machine Coordinates Not Changing
Post by: joeaverage on June 23, 2018, 08:14:13 PM
Hi,
OK that sounds like its operating normally.

When you say that the current position changes when you jog then some if not all of the numbers that make up the current position must also change.

If you look on the Diagnostics page you will see that the current position is:

Current Position = Machine Coordinate - Work Offset - G92 Offset - Tool Offset.

Its common for the G92 Offset to remain zero for the entire Mach session and unless you are actively using tool offsets the Tool Offset will be fixed or zero for the time being.
Thus if the Current Position is changing then either (or both) the Machine coordinate or Work Coordinate MUST be moving also. Does it do so?

Craig
Title: Re: Z Axis Machine Coordinates Not Changing
Post by: tjb1 on June 23, 2018, 08:15:09 PM
Hi,
OK that sounds like its operating normally.

When you say that the current position changes when you jog then some if not all of the numbers that make up the current position must also change.

If you look on the Diagnostics page you will see that the current position is:

Current Position = Machine Coordinate - Work Offset - G92 Offset - Tool Offset.

Its common for the G92 Offset to remain zero for the entire Mach session and unless you are actively using tool offsets the Tool Offset will be fixed or zero for the time being.
Thus if the Current Position is changing then either (or both) the Machine coordinate or Work Coordinate MUST be moving also. Does it do so?

Craig

The only number that changes when jogging Z is current position.  Machine, Work, and G92 all remain 0.
Title: Re: Z Axis Machine Coordinates Not Changing
Post by: joeaverage on June 23, 2018, 08:37:43 PM
Hi,

Quote
The only number that changes when jogging Z is current position.  Machine, Work, and G92 all remain 0.

That seems impossible to me. I think that your copy of Mach3 may be corrupt.

Craig
Title: Re: Z Axis Machine Coordinates Not Changing
Post by: tjb1 on June 23, 2018, 09:22:00 PM
Hi,

Quote
The only number that changes when jogging Z is current position.  Machine, Work, and G92 all remain 0.

That seems impossible to me. I think that your copy of Mach3 may be corrupt.

Craig

I reinstalled and it's working as expected now, thanks.
Title: Re: Z Axis Machine Coordinates Not Changing
Post by: tjb1 on June 23, 2018, 09:26:02 PM
Hi,

Quote
The only number that changes when jogging Z is current position.  Machine, Work, and G92 all remain 0.

That seems impossible to me. I think that your copy of Mach3 may be corrupt.

Craig

I reinstalled and it's working as expected now, thanks.

Scratch that, switched to the plasma screen and it quit working.  Loaded the default screen and it worked again...seems to not work on plasma.
Title: Re: Z Axis Machine Coordinates Not Changing
Post by: ger21 on June 23, 2018, 09:35:58 PM
It's probably a different DRO #.
Title: Re: Z Axis Machine Coordinates Not Changing
Post by: tjb1 on June 23, 2018, 09:41:10 PM
I opened the screen in the editor and that readout was set to code 86 while the 1024 screenset has it as 85, I changed it to 85 in the plasma screen and its now working.  I'm not sure what 86 is or how to find out but maybe that should be changed so the included plasma screen works correctly?
Title: Re: Z Axis Machine Coordinates Not Changing
Post by: joeaverage on June 23, 2018, 10:28:49 PM
Hi tbj1,
that explanation makes sense, you were looking at the wrong DRO. That does raise the question why the DRO number has been changed for the Plasma screen.

As you may know Mach4 allows for THC control it is in fact enacted by the motion controller rather than Mach. At this time there is only one external motion controller
manufacturer who has devoted the effort to enact THC and provide a custom screen  for its Mach4 controller. Because of the rapidity at which Mach4 software cycles
there may be the opportunity to do THC by scripting within Mach4 with minimal controller support required ie a software solution rather than a realtime hardware solution.

http://www.machsupport.com/forum/index.php/topic,37405.msg255859.html#msg255859 (http://www.machsupport.com/forum/index.php/topic,37405.msg255859.html#msg255859)

The essential idea is that the Z axis remains just that but in addition you piggyback an out-of-band axis on top of the Z axis to wiggle up and down for THC purposes and not
therefore break the axis coordination that manipulating the Z axis directly would imply. It would of course be possible to wiggle the Z axis as if it were an out-of-band axis but the Z axis
DRO would not follow the THC variations. The actual  (total) position of the Z axis would then be the sum of the Z axis DRO proper and the THC variation, possibly in a second DRO.

My suggestion is that the #86 DRO in the Plasma screen is analogous to the second DRO tracking THC variations as proposed for Mach4.

Craig
Title: Re: Z Axis Machine Coordinates Not Changing
Post by: ger21 on June 23, 2018, 10:52:03 PM
http://www.machsupport.com/Mach3Wiki/index.php?title=OEM_DROs

86 is the  A axis Machine Coordinate DRO.