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Author Topic: Safe Z (again)  (Read 2514 times)

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Offline Davek0974

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Safe Z (again)
« on: August 01, 2014, 10:04:42 AM »
Hi

could someone spare a minute to explain what safe-z actually does or should do in respect to a plasma table??

I have been seeing the "safe-z turned off......" message today, but it makes little sense. I have tried various settings in the safe-z screen but nothing seems to do what i would expect it to, probably my fault ;)

When is safe-z called?

I have tried the "make safe-z an incremental rise" but that seems to do little :)

Any advice would be helpful, even if its just "turn it off" as long as that is followed by how to turn it off :)

Dont forget this is a plasma so Z DRO is zeroed at the top of the workpiece NOT the top of Z travel, this effectively means that Z machine co-ords are never zeroed, currently it seems to think that machine Z zero is at table surface -4mm !!!
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Hood

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Re: Safe Z (again)
« Reply #1 on: August 01, 2014, 05:44:17 PM »
Safe Z  is used if you do a RFH and also if you press the GoToZ button.

How useful in Plasma I dont know, will depend on how you restart I suppose.

Hood

Offline Davek0974

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Re: Safe Z (again)
« Reply #2 on: August 02, 2014, 03:33:10 AM »
Hmm, I read about this gotoZ button but my screen set not seem to have it.

I do have a goto zero button is that the same?

Looking at it another way, if I don't have it then I probably don't need it as I never knew it existed.:)

Is RFH ref home or all ? If so the my z axis does not move when doing doing a ref all, it can't as there could be nothing under the torch and it will simply plant itself in the slats.

My Z axis machine coordinates never gets zeroed and seems to be at some arbitrary point about 5mm below bed level?

Is there a way to zero machine coordinates manually?
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Hood

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Re: Safe Z (again)
« Reply #3 on: August 02, 2014, 04:52:12 AM »
RFH = Run From Here.

Regarding your Z not zeroing, if you have a home switch and have it enabled then it should move and zero. The only reason it would not zero is if you do not have the Auto Zero chosen in Homing and Limits OR you have a value in Home Off (Home Offset) box.

Having said that however, you may not be homing the Z on a plasma, maybe you are doing a probing routine to find the material surface and setting the Z work offset.

Hood

Offline Davek0974

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Re: Safe Z (again)
« Reply #4 on: August 02, 2014, 07:07:42 AM »
Yes that's exactly what it does, I use a probing routine in SheetCam to find the surface before every pierce happens.

Have not used run from here yet :)

I don't really know if the odd value for my Z zero machine DRO matters, I know the work DRO get zeroed each time it probes.

It does have a home switch but that's at the top and just functions as a limit switch now incase I rack the z up manually too far. No point in homing a z axis on a plasma as it's always changing with material thickness and warpage etc.

Is there a way to manually zero a machine DRO?
« Last Edit: August 02, 2014, 07:09:13 AM by Davek0974 »
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Hood

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Re: Safe Z (again)
« Reply #5 on: August 02, 2014, 03:54:08 PM »
I do not know the setup and routine you have so not sure whether having the Z home or not would matter.
If you wanted the Z to home then you could just set the switch,  you currently use for a limit, as a home switch. Then when you press RefAll the Z should raise up to that switch and set machine coords zero there.

You can set the axis zero via script but easiest way is just do as above but as said whether you need to or not will depend on your routine, probably you dont need to.


If you dont have any home switch defined for the Z Home then when you press the RefAll button it should set machine coords for Z to zero at that point.

Hood

Offline Davek0974

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Re: Safe Z (again)
« Reply #6 on: August 10, 2014, 11:51:32 AM »
Thanks Hood,

I'm not convinced having it zero is important at all, the only thing that's annoying me is that the machine coordinate for z zero is meaningless at present, being some 5mm below the table surface.

I will check what setting I have for homing on z and see what can be done.

For plasma the machine DRO means very little, it always zeroes the working DRO on every pierce and that DRO is all tha matters I think.

Will have another play when I get a chance.
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives

Offline Davek0974

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Re: Safe Z (again)
« Reply #7 on: August 11, 2014, 06:03:04 AM »
Had another look and the z axis limits screen is set at +/- 5000 so that's not being used, when I started using the probing option for each pierce, the Z zero was removed from the Home-All button code so now that button only homes & zeroes X and Y, Z just remains at it's last parked position which is set in sheetcam as 20mm above the last known probe-zero point.

If i press GotoZero though I still get that annoying warning re safe-z being turned off and ignoring it, can that be stooped?
Bridgeport Mill, Mach3 V062, CSMIO-IP/A controller, AC Servo Drives