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Author Topic: Z constantly sets itself higher than it was zeroed at.  (Read 724 times)

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Z constantly sets itself higher than it was zeroed at.
« on: February 28, 2018, 06:36:16 PM »
I'm on a Taig Micromill running a custom fusion 360 post processor. When I zero my Z and then hit cycle start, the processor has the Z go up and hit the soft limits for a tool change, then asks to resume, which it usually does so by going down and hovering .6" above the part, then waits for me to cycle start. I am on the latest version of Mach 3 (I hear that an older version works better?) So like 50 percent of the time when the tool goes down to it's .06" hover, it will either stop 2" above the part, seemingly having reset itself to a new Z, or it will try to bury itself into the work.

This issue seems to occur more after I have been working for a while, loading a few different programs, having Mach open for an extended time. If I restart mach, or sometimes the whole PC the Z issue clears up. Also, sometimes after a while when I try to jog my pendant wheel in .001" increments all motion will lock up.

Any ideas? Should I go to the older version of Mach 3?  Also, can I do that if my software is licenced under the person I bought the system from?

Thanks
Ben
Taig Micro Mill. 1/4-20" lead screw. Powered by 1.25hp router with a 4:1 pulley reduction. Driven by Ethernet SmoothStepper to a Gecko 6540. Nema 23 motors. 3 Axis.
Re: Z constantly sets itself higher than it was zeroed at.
« Reply #1 on: February 28, 2018, 06:57:07 PM »
Hi,
does the Z DRO correctly reflect where the axis ACTUALLY is or where it SUPPOSED to be?

Craig
My wife left with my best friend...
     and I miss him!
Re: Z constantly sets itself higher than it was zeroed at.
« Reply #2 on: February 28, 2018, 07:02:55 PM »
The DRO reads .6” but it’s actually more like 2”

Also sometimes when I hit start I see a flicker of what might even be a value of the x or y axis n the z DRO. Could be my imagination. But for sure, somehow, values are getting added to Z after I set it to zero and cycle start.
Taig Micro Mill. 1/4-20" lead screw. Powered by 1.25hp router with a 4:1 pulley reduction. Driven by Ethernet SmoothStepper to a Gecko 6540. Nema 23 motors. 3 Axis.
Re: Z constantly sets itself higher than it was zeroed at.
« Reply #3 on: February 28, 2018, 07:28:27 PM »
Hi,
sounds like Mach is trying to drive to the correct place but the axis is not following.

I think a series of MDI commands excersising the Z axis up and down is in order. I suspect you will find that
the axis is missing steps.

G1 Z50 F500
Z0
Z50
Z0
Z50
Z0

should see the z axis go up and down 50mm at 500mm/min. If it doesn't end up where it started then you are losing steps.

Craig
My wife left with my best friend...
     and I miss him!
Re: Z constantly sets itself higher than it was zeroed at.
« Reply #4 on: February 28, 2018, 07:34:22 PM »
Thanks! I’ll try this next time I get out there. So even though I hear or see no issues, Z could still be losing steps?  2” worth of steps?
Taig Micro Mill. 1/4-20" lead screw. Powered by 1.25hp router with a 4:1 pulley reduction. Driven by Ethernet SmoothStepper to a Gecko 6540. Nema 23 motors. 3 Axis.
Re: Z constantly sets itself higher than it was zeroed at.
« Reply #5 on: February 28, 2018, 09:22:52 PM »
Hi,
could be, won't know until you try.

Craig
My wife left with my best friend...
     and I miss him!