Joints_Axis help

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29 Aug 2016 14:29 #79657 by oddwick
Joints_Axis help was created by oddwick
I was wondering if somebody would be willing to post a working sample ini and hal for a xyyz joints_axis setup for a stepper driven machine?

my problem is thus:

i have been using linuxcnc for some years now around 90% "out of the box" so to speak on several different machines and have loved it. of course the alternative is windows, which falls into the category of things i avoid (bubonic plague, great white sharks, microsoft, etc). i have recently built a large format router and the idea of being able to square it through software was intriguing.

the wall that i am running into is that linuxcnc's documentation is spartan even by linux standards. and conflicting. i have scoured these forums and google and you would think that as common as gantry routers are, there would be easier to find examples.

right now i have upgraded to 2.7.6 from 2.4 on precise and that went without a hitch. i tried with no success to get my hands on JA14, but couldn't seem to get it to work, but then i read that it was integrated into the master branch. so far, using the sample configs and a lot of google, i have managed to get a working configuration that homes the y on separate switches, but it uses a xyza setup which is far from pretty!

in addition, now it ignores my settings in the ini for max_velocity on the z and tries to spin it at full jog speed even though it can't turn that fast! so now i have to toggle the jog speeds overtime i move a different axis. (no more vulcan death jog!) and if i forget and move the z and it seizes, then i have to toggle back to joint mode and re-home my z while remembering NOT to jog the y before switching back to teleop or risk seriously racking the machine. i rather liked it when it was power on, home, cut.

i have seen snippets of JA ini's and that looks to be an elegant solution. the problem is that i can't seem to find anything beyond snippets of ini's and hal's to go off of. what would be really nice would be an actual guide on how to set up a multi motor machine rather than a few lines in a change log saying that there a are some differences between JA and master. different from what? where do you begin? stepconf only gets you so far. would anybody more knowledgable please help me out?

on a side note, is there any way to turn off warnings when you hit soft limits now? before, the machine just stopped, now i get errors and it powers down when I'm not paying attention to keyboard orientation and jog y wrong way after homing.

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29 Aug 2016 14:36 #79658 by andypugh
Replied by andypugh on topic Joints_Axis help

what would be really nice would be an actual guide on how to set up a multi motor machine rather than a few lines in a change log saying that there a are some differences between JA and master.


The INI file docs have been updated:
linuxcnc.org/docs/devel/html/config/ini-config.html

See specifically the sections on [KINS], [AXIS] and [JOINTS]

There is a suggestion to read the kins manpage there, too, but that is also here:
linuxcnc.org/docs/devel/html/man/man9/kins.9.html

Again, it tells you everything you need to know, not one iota more, and assumes you know absolutely everything else already :-)

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29 Aug 2016 14:37 #79659 by andypugh
Replied by andypugh on topic Joints_Axis help
And here is a sample INI file, as part of the sample Gantry config.
github.com/LinuxCNC/linuxcnc/blob/master.../sim/axis/gantry.ini

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29 Aug 2016 14:49 #79661 by oddwick
Replied by oddwick on topic Joints_Axis help
thank you so much for the quick reply. that ini is totally different than the one that is included in the sample configs. it uses an xyza and gantrykins, which is what i was trying to avoid because it seems cumbersome.

Again, it tells you everything you need to know, not one iota more, and assumes you know absolutely everything else already :-)


and that is where my problem is, i needed a bit of a more ground up approach, being neither developer or machinist, but somewhere in-between!

again, thanks for the reply and as soon as i get back to the shop, i will give it a whirl.

also any clue as to why it is ignoring my max velocity on each axis? or is it just the gantrykins implementation in general?

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29 Aug 2016 14:51 #79662 by seb_kuzminsky
Replied by seb_kuzminsky on topic Joints_Axis help
The local hacker space has a big gantry machine running the LinuxCNC development branch (aka "master"), which as you say now includes the Joints/Axes work.

The git repo with the config is here: github.com/SolidStateDepot/ssd-shopbot

The config was auto-converted from a working 2.7 config. The auto-converted config mostly worked, but needed a few manual tweaks. The git history for the project shows exactly what we changed (interspersed with other, unrelated changes). From memory, i think two things needed updating: the "extra A axis" problem you noted, and [TRAJ]AXES.

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29 Aug 2016 14:55 #79665 by seb_kuzminsky
Replied by seb_kuzminsky on topic Joints_Axis help

on a side note, is there any way to turn off warnings when you hit soft limits now? before, the machine just stopped, now i get errors and it powers down when I'm not paying attention to keyboard orientation and jog y wrong way after homing.


After including the JA changes, your homed gantry machine should never run into its soft limits. Are you sure you're not running into your joint limit switches (aka hard limits)?

Our gantry machine had that problem after updating, and i tracked it down to a mismatch between the [JOINT_*] limits and the [AXIS_*] limits in my ini - the axis limits were larger than the joint limits, so the soft limits (aka axis limits) would not protect the machine from running into its hard limits. Making the axis limits just slightly more restrictive than the joint limits fixed this issue for us.
The following user(s) said Thank You: oddwick

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29 Aug 2016 14:57 #79667 by Todd Zuercher
Replied by Todd Zuercher on topic Joints_Axis help
First thing, you have to be running the current Master branch (or an older JA experimental branch) to use the new JA style joint mappings, 2.7 can't do it. Are you in fact running Master now?

To get rid of the spurious A axis, in your ini file you need to change the Coordinates = line in the [TRAJ] section.
If your joints are 0=x, 1=y, 2=z, 3=y your coordinates line should be:
COORDINATES = X Y Z Y

If you are running Master, there should be example simulation gantry configs that you can load, run, and look at. Unfortunately I think the sim hal files are rather confusing for a beginner. (they use hal TCL)

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29 Aug 2016 15:21 - 29 Aug 2016 15:53 #79669 by dgarrett
Replied by dgarrett on topic Joints_Axis help
With joints_axes it is especially important that ini settings are consistent.
Ref:
linuxcnc.org/docs/devel/html/getting-sta..._axes_specifications

When trivkins is specified without a coordinates= setting, the trivkins
module uses a default set of coordinates, namely xyzabcuvw assigning
consecutively to joints 0,1,2,.. This default is _not_ appropriate for a
gantry that uses multiple joints for a single coordinate letter.

Note that there will not be an extra or spurious A axis when ini settings
are consistent:
[KINS]
KINEMATICS = trivkins coordinates=xyzy kinstype=BOTH
JOINTS = 4
...

[TRAJ]
COORDINATES = XYZY
...
Last edit: 29 Aug 2016 15:53 by dgarrett.
The following user(s) said Thank You: oddwick

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29 Aug 2016 16:23 #79671 by andypugh
Replied by andypugh on topic Joints_Axis help

thank you so much for the quick reply. that ini is totally different than the one that is included in the sample configs.


Actually, it is exactly the one from the sample configs. But from the 2.8 / JA sample configs.

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29 Aug 2016 16:51 #79672 by oddwick
Replied by oddwick on topic Joints_Axis help
i just went and took a look at the ini you linked to and it is totally different from the one included in the gantry sample! this is what i was looking for and this is the first time ive seen the shared home flag. i would have failed spectacularly with that one.

do you by chance have a sample hal with that?

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