More help with two steppers on one axis please

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11 Jul 2017 10:08 #95650 by aaron
aaron created the topic: More help with two steppers on one axis please
Hi
i have upgraded linuxcnc to 2.7.9 and almost configured my Router to run Gantry-hs with two steppers on the x axis gantry. I have a couple of major problems.
Homing, I can zig zag the gantry back close to the sensors and then run home on the individual joints, but I am not happy with this method there is too much wracking on the gantry. Please, can someone tell me how can I get the the joints to home at the same time.

When I jog individual axis in joint mode I get good fast movement. After homing all joints and switching to world mode when I try a fast jog of an axis I get a joint following error. Also, when I did a G0 command for the x axis ( the one with two motors) the diver for the 'A' axis, or joint 4, cut out with and error light. (worrying)


I am not good at editing files and would rather use some kind of configuration tool if it exists. Is it easier to do this in the 2.8 version? and how stable is it (this machine is my main business)

Thanks for any assistance

Aaron
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11 Jul 2017 14:43 #95669 by Todd Zuercher
Todd Zuercher replied the topic: More help with two steppers on one axis please
Yes,
2.8 is stable from the regard that it works fine, and there are lots of people running machinery with it.
Often in the Linux community a development branch is refereed to as not stable, because it is in a state of flux, with new features continually being added and developed.
It means that if you perform a software update, you could introduce a change that could break your configuration or introduce a bug. This is the case with Master (2.8-pre)
It does not mean that the software will run in an unstable fashion and crash unpredictably.

So If you install Master and set up a configuration for your machine, and it works fine for your application, There is not much to fear. (so long as you don't update.)

If you use Master for your machine and you find a bug for your application, report it and it should quickly get fixed.

When (or if) you update a Master system, be sure to carefully observe machine operations for a time to make certain nothing awful happens.

For these reasons I prefer not to run Master on a machine in a production environment, unless features only found there are required for that application. (I am not currently running any machines with Master, but I have in the past when 2.6 and 2.7 were considered the Master branches, and I never had any real problems.)
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11 Jul 2017 17:34 #95678 by rodw
rodw replied the topic: More help with two steppers on one axis please
Aaron, I have a near finished gantry machine running on Master which includes the joint axis (JA) code which is exactly what you need to fix your homing problems. In fact I'm using another experimental branch with features that I want to use for my plasma cutter so it lags behind master a bit. This has been a slow build for me and I can vouch for the stability of the build. I've found a few bugs and as Todd has said, they've been fixed quickly. I think JA had a fairly significant impact on the LCNC internals and from what I can see, the bugs I've seen have mostly been in the GUI's (Axis and Gmocappy) as they have had to make changes to catch up with the new JA core.

About six months ago Gmocappy had problems which could rack the gantry. Fortunately, my gantry motors were just sitting on the floor at the time so no damage was done. I reported it and it was fixed pretty quickly. Last weekend, I finally got my homing switches working and it was a few minute job to square the gantry by altering the homing offsets in the ini file. Now, I can push one side out of square, home the machine and it is squared again. The gantry support has been flawless.

All you need to do is to set the homing sequence to be the same negative number for both sides of the gantry and you are in business. This is all well covered in the V 2.8 homing sequence docs.

Also check the KINSTYPE entry in your ini file
[KINS]
JOINTS = 4
KINEMATICS = trivkins coordinates=XXYZ

If it says something like
[KINS]
JOINTS = 4
KINEMATICS = trivkins coordinates=XXYZ kinstype=BOTH

Try deleting the KINSTYPE setting as that enables joint mode jogging and homing which you don't want on a gantry machine. That is something I found was a requirement when I found my bug. I'm not sure if that helps in V 2.7
The following user(s) said Thank You: joel0407
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13 Jul 2017 13:00 #95755 by aaron
aaron replied the topic: More help with two steppers on one axis please
Hi
Thanks very much for your replies to date.
I have updated to 2.8, run stepconfig wizard and tried to edit the ini and hal files to match some example files, but it I think it is beyond me. I am trying for an XXYZ machine with an A (rotary) axis
Currently I am getting the Axis window up, but I cannot click the power button (on the screen). When opened from the terminal i am getting this error:

Individual axis homing is not currently supported for
KINEMATICS_IDENTITY with duplicate axis letter <X>

Could I ask somebody take a look at my config files? I would be very grateful if you could tell me where I am going wrong.

Kind regards

Aaron
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13 Jul 2017 14:33 #95758 by Todd Zuercher
Todd Zuercher replied the topic: More help with two steppers on one axis please
I think you have to specify a home sequence number for all of the axis. (you don't have one for Z and A)
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13 Jul 2017 19:47 - 13 Jul 2017 19:47 #95774 by rodw
rodw replied the topic: More help with two steppers on one axis please
Here is a working Joint axis .ini file. But it does not have the A axis. There are a few more settings for each joint becasue I am using a MESA 7i76e. Good luck. It will be something simple.

File Attachment:

File Name: Spaceship_..._PID.hal
File Size:21 KB
Attachments:
Last Edit: 13 Jul 2017 19:47 by rodw.
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13 Jul 2017 20:55 #95775 by Clive s
Clive s replied the topic: More help with two steppers on one axis please
Rod I think you have attached the hal file instead of the ini.
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13 Jul 2017 22:45 #95776 by rodw
rodw replied the topic: More help with two steppers on one axis please
Sorry, Try this one

File Attachment:

File Name: Spaceship_...PID1.ini
File Size:7 KB
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14 Jul 2017 20:06 #95803 by aaron
aaron replied the topic: More help with two steppers on one axis please
Hi
So, I am still struggling with configuring this. The one thing that is really bugging me is, no matter what I do there is still an A axis shown on the Axis screen. How do you map the A axis (generated by stepconfig) to the new X2 Axis? Please could somebody point me to some simple xxyz stepper hal and ini files.
Kind regards
Aaron
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14 Jul 2017 21:16 #95806 by Todd Zuercher
Todd Zuercher replied the topic: More help with two steppers on one axis please
What is shown on the display and what is X2 are not necessarily the same thing. And there are two places in the ini file that pertain to this.
If your joints are X-0, Y-1, Z-2, and X2-3, in the TRAJ section there should be a line
COORDINATES = XYZA
(or something like that). This designates the axis letters that are displayed. There can be no duplicate letters on this line. Change it to:
COORDINATES = XYZ
to only show those axis letters on the DRO.

The other place that pertains to this is in the KINS section. This is where you connect the axis letters to the joint numbers.
KINEMATICS = trivkins coordinates=xyzx
(or something simular)
The coordinates= part of the line matches the axis letter to the joint in numerical order. In my example X is connected to the 1st and 4th joints (Joint0 and Joint3).
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