Lathe Z axis/joint not homing after updating to 2.8

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22 May 2019 20:20 #134607 by vmihalca
Hi guys,

In my attempt to use gmoccapy 3.x on my mill, I've updated to 2.8.
The mill software works fine, however when I try to home the lathe, the X axis homes fine, the Z axis does not home. If I click home axis again, it says "this joint is already homed". The homed icon does not appear near to the Z axis.
If i try to execute an MDI command it says that it cannot execute command while not homed.
Also the pendant does not seem to work anymore.

Here are my configs:
github.com/85vmh/LinuxCncConfigs/tree/master/configs/test_setup

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22 May 2019 20:32 #134610 by rodw
There seems to be a fair bit missing from your config files as there are only 2 joints configured. (X & Z)

I think i would make a totally new config with pncconf that at least moves your axes. Then merge in your custom config from your existing files

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22 May 2019 20:50 #134612 by vmihalca
Since its a lathe, its normal to be only x and z.
Is there something missing for these axis?

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22 May 2019 20:52 #134613 by rodw
Sorry, you said mill in your first post so I missed the lathe part.

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22 May 2019 20:56 #134615 by cmorley
i have seen this behavior on a test lathe. i have not looked into it yet,I had another way to start the homing behavior - so I expect it's an AXIS problem.

Chris M

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22 May 2019 21:07 - 22 May 2019 21:12 #134617 by rodw
IN your ini file you seem to be missing coordinates= here so LinuxCNC can't map joints to axes.
# from my gantry machine
[KINS]
JOINTS = 4
KINEMATICS = trivkins coordinates=XXYZ

I'm not sure if you can set this up using joints 0 and 2 as you have as that line maps the axes to the joints so I suspect you may need to move your Z axis to joint 1. I have not looked at the syntax to skip one (ie X?Z) so you need to check the docs before you hack into the wiring.
Last edit: 22 May 2019 21:12 by rodw.

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22 May 2019 21:11 #134619 by rodw
It seems from the docs you can't use joint 2 without a joint 1
linuxcnc.org/docs/devel/html/config/ini-...g.html#_traj_section

I wonder if this was thought about when the joint axes code was added?

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22 May 2019 21:49 #134621 by Clive s
In the ini file you have axis = 3 but you only have X and Z !!

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22 May 2019 21:54 #134622 by rodw

rodw wrote: It seems from the docs you can't use joint 2 without a joint 1
linuxcnc.org/docs/devel/html/config/ini-...g.html#_traj_section

I wonder if this was thought about when the joint axes code was added?


What I mean by this comment is that this potentially will break any lathe config when its automatically converted to V2.8 which moves from fixed mapping between joints and axes to independent axes as there is no method to skip a joint in the kinematics statement.
Seems like we need to support something like
KINEMATICS = trivkins coordinates=X-Z
in the coordinates string so the existing config works correctly as I don't think you can reorder the stepgens on a Mesa card.

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22 May 2019 21:58 - 22 May 2019 21:59 #134623 by rodw

Clive s wrote: In the ini file you have axis = 3 but you only have X and Z !!


This is part of the problem, potentially a bug (or at least an undesirable feature). He needs 3 axes to get a joint 2 to suit his hardware but he can't tell his config to use stepgen2 so he has to move his motors to stepgen 1 as it stands now.
Last edit: 22 May 2019 21:59 by rodw.

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