MPG working with joint but not with axis ??? [solved]

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17 Aug 2022 01:18 #249925 by JPL
Mystery Solved!!! 

The reason why the MPG was not working with 'axis.x' is simply because ALL the axis should be homed before that. Not just the single axis controlled by the MPG. I did not realized that on my (lathe) config since I had only one motor connected for the x axis and did not even tried to home the z axis because of that.

More specifically it appears that jogging axis is allowed only in teleop mode while jogging joints is only allowed in Joint-mode (aka Free mode)...

But this, for example, will allow jogging in both mode: (although not recommended)

setp    axis.x.jog-vel-mode 0
net x-jog-enable         =>  axis.x.jog-enable
net x-jog-count          =>  axis.x.jog-counts
net selected-jog-incr    =>  axis.x.jog-scale


net x-jog-enable         =>  joint.0.jog-enable
net x-jog-count          =>  joint.0.jog-counts
net selected-jog-incr    =>  joint.0.jog-scale

sets x-jog-enable    true
sets selected-jog-incr     1.00000

 

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17 Aug 2022 01:28 #249926 by JPL

I think all axes likely need homing before your MPG is used..
 

Aka Rod was right
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17 Aug 2022 02:54 #249928 by cmorley
Ahh that what Rod mentioned.
What do you meN nor recommended?
I am surprised pncconf did not connect Hal in that way actually.

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17 Aug 2022 19:28 #249968 by JPL
AFAIK most (if not all) industrial robots do not allow jogging before homing all the axes. I have an older Adept cartesian robot as well as a Yamaha cartesian robot and neither of them allow any motion before homing.

I can see a few reasons why:

- The position is unknown before homing (except with absolute encoders). Software limits are then useless, DRO is then useless too. Limit switches may not work if you're past the detection point.

- With gantry machine, or any machine with more than one joint per axes, problems may happen if a single joint is moved (ex racking)

- With a correct homing procedure there is simply no need for jogging before homing and in fact LinuxCnc has everything needed for that.
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18 Aug 2022 06:23 #249999 by sprintertrd
Interesting, I have a old CNC mill that allows axis jogging before homing and does not have absolute encoders. You can even set a 0 XYZ work position run G code but at a reduced maximum feed rate.

I would guess that on initial setup of the mill the home positions are set, the XYZ travels are hard coded in the software and from there on the position of the axis are saved in memory. If it is turned off it knows where it is on the next power-up.

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