Programs always exceed positive Z limit at end

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09 Oct 2019 10:47 #147552 by JetForMe
I’m just getting my router up and running, using Fusion 360’s generic linuxcnc.cps post processor to post to the machine, and one thing that always happens is at the end of the run, it trips hitting the soft positive Z limit. You can see it in the attached screenshot, which also shows the tail end of the gcode that ran. It runs normally in G54 with z=0 set to the top of work, more than 200 mm below the top of the Z-axis. Going to G53 Z0 should be fine; I can do it manually without tripping things (I think).

Any ideas? Thanks!
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09 Oct 2019 11:15 #147555 by Clive S

JetForMe wrote: I’m just getting my router up and running, using Fusion 360’s generic linuxcnc.cps post processor to post to the machine, and one thing that always happens is at the end of the run, it trips hitting the soft positive Z limit. You can see it in the attached screenshot, which also shows the tail end of the gcode that ran. It runs normally in G54 with z=0 set to the top of work, more than 200 mm below the top of the Z-axis. Going to G53 Z0 should be fine; I can do it manually without tripping things (I think).

Any ideas? Thanks!


Try bringing the soft limit down a bit . It might be overshooting

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09 Oct 2019 13:03 - 09 Oct 2019 13:09 #147558 by Leon82
Try g90go g49g53.

Do you have a home offset for homeing?
Last edit: 09 Oct 2019 13:09 by Leon82.

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09 Oct 2019 14:57 #147567 by tommylight
In gcode you have 15mm, in the screenshot it is at 208mm ? How ? Why ?
Do you have a G21 at the top of gcode ?

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10 Oct 2019 02:18 - 10 Oct 2019 02:18 #147607 by JetForMe

In gcode you have 15mm, in the screenshot it is at 208mm ? How ? Why ?
Do you have a G21 at the top of gcode ?


Yeah, I've attached the program. The Z15 is in G54, which has z=0 set to the top of work.
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Last edit: 10 Oct 2019 02:18 by JetForMe.

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10 Oct 2019 02:19 #147608 by JetForMe

Try bringing the soft limit down a bit . It might be overshooting


Wouldn't the machine know to slow as it approaches the target position? It does that for all other moves.

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10 Oct 2019 07:33 #147616 by JetForMe
The homing configuration for the Z axis looks like:
HOME = -5.0
HOME_OFFSET = 5.0
HOME_SEARCH_VEL = 25
HOME_LATCH_VEL = -5
HOME_SEQUENCE = 0
HOME_USE_INDEX = False
HOME_IGNORE_LIMITS = True

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10 Oct 2019 08:15 #147618 by Clive S
What are the soft limits set at?

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10 Oct 2019 09:30 #147623 by tommylight

JetForMe wrote:

In gcode you have 15mm, in the screenshot it is at 208mm ? How ? Why ?
Do you have a G21 at the top of gcode ?


Yeah, I've attached the program. The Z15 is in G54, which has z=0 set to the top of work.

That is all good, but how did you get Z to go up to positive 208mm ? I do not see any offsets active in that screenshot.

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10 Oct 2019 20:53 #147649 by JetForMe

tommylight wrote: That is all good, but how did you get Z to go up to positive 208mm ? I do not see any offsets active in that screenshot.


I've attached the full .ini file. I'm pretty sure that's 208 mm in G54.
[AXIS_Z]
MIN_LIMIT = -340.0
MAX_LIMIT = 0.0
MAX_VELOCITY = 200
MAX_ACCELERATION = 1000


[JOINT_3]
AXIS = Z
MIN_LIMIT = -340.0
MAX_LIMIT = 0.0
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