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23 Aug 2019 18:47 #142991 by Clive S
Replied by Clive S on topic moving problem
Just to be clear BOTH joints on the gantry HAVE to have -1 ie. not just one of them.

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23 Aug 2019 19:03 - 23 Aug 2019 19:31 #142993 by dgarrett
Replied by dgarrett on topic moving problem

Just to be clear BOTH joints on the gantry
HAVE to have -1 ie. not just one of them.


Incorrect, Please see the docs:
If any joint has a negative HOME_SEQUENCE
value, then all joints with the same absolute
value (positive or negative) of the HOME_SEQUENCE
item value will synchronize the final move.

Ref: linuxcnc.org/docs/2.8/html/config/ini-ho....html#_home_sequence

But, it makes sense to be consistent and use a negative
HOME_SEQUENCE value for all joints intended to have
synchronization of the final homing move.
Last edit: 23 Aug 2019 19:31 by dgarrett.
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23 Aug 2019 19:10 - 23 Aug 2019 19:11 #142994 by dgarrett
Replied by dgarrett on topic moving problem

In 2.8 and 2.9 with tandem homing, do not
jog the machine before homing as it will be in
joint mode so Y1 in your case will jog with
pgup/pgdown buttons, insead of Z axis, causing the
gatry to bend.


This is *not* correct when configured to synchronize
the final homing move by specifying a negative
HOME_SEQUENCE.

Please see the docs:
Joint mode jogging of joints having a negative
HOME_SEQUENCE is disallowed. In common gantry
applications, such jogging can lead to
misalignment (racking). Note that conventional
jogging in world coordinates is always available
once a machine is homed.

Ref: linuxcnc.org/docs/2.8/html/config/ini-ho....html#_home_sequence
Last edit: 23 Aug 2019 19:11 by dgarrett.
The following user(s) said Thank You: BigJohnT, tommylight, rodw, RoberCNC

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23 Aug 2019 19:19 #142997 by RoberCNC
Replied by RoberCNC on topic moving problem
Thanks a lot Garrett for this info,

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23 Aug 2019 20:05 #143002 by tommylight
Replied by tommylight on topic moving problem

dgarrett wrote:

In 2.8 and 2.9 with tandem homing, do not
jog the machine before homing as it will be in
joint mode so Y1 in your case will jog with
pgup/pgdown buttons, insead of Z axis, causing the
gatry to bend.


This is *not* correct when configured to synchronize
the final homing move by specifying a negative
HOME_SEQUENCE.

Please see the docs:
Joint mode jogging of joints having a negative
HOME_SEQUENCE is disallowed. In common gantry
applications, such jogging can lead to
misalignment (racking). Note that conventional
jogging in world coordinates is always available
once a machine is homed.

Ref: linuxcnc.org/docs/2.8/html/config/ini-ho....html#_home_sequence

Thank you , i did notice that happeneing most of the time, but sometimes i could jog it without homing. Did not have time to check why or how as that is a production machine in use every day all day.
Thank you, D.

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23 Aug 2019 21:03 - 24 Aug 2019 20:42 #143012 by rodw
Replied by rodw on topic moving problem

RoberCNC wrote: so with what you say and if I have drawn a correct conclusion from what I am reading it is as simple as adding the "Home_sequence" section within each of the joints in the INI file of the configuration created with the Y tandem and the two assigned to the duplicated axis put -1 which will create me the Home all axis button, will move both simultaneously, and will give me an interface with XYZ after the cycle, the only thing that forces me to always start the machine with Homing.


Thats about it. and get this bit right for your joint order
[KINS]
KINEMATICS              = trivkins coordinates=xyyz
JOINTS                  = 4

The kinematics command is the only thing that connects the axes to a given joint.
You might need to cut and paste the stepgen commands in HAL so you have 4 of them.

You need to make sure the home switch remains engaged all the way to the limits. Linuxcnc costs a fair way when homing if you home at a reasonable speed.
Last edit: 24 Aug 2019 20:42 by rodw.
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24 Aug 2019 07:06 - 24 Aug 2019 07:07 #143060 by RoberCNC
Replied by RoberCNC on topic moving problem
Thank you very much to all for the interest, time and information provided, I will soon see if I can get it. I'm glad to see how this is becoming a meeting point and knowledge exchange :)

Rod, that's one of the things I tried yesterday, besides the information was yours, from another thread around here, I observed that putting the third option or not is what makes XYZ or the joints appear in the GUI.
Last edit: 24 Aug 2019 07:07 by RoberCNC.
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25 Aug 2019 09:11 #143125 by RoberCNC
Replied by RoberCNC on topic moving problem
Let's see ... I have made a new configuration with the dual Y and put the double homing, and by the way added a 4 rotary axis. Just as you said the double homing goes great, establishing the sequence with the sign -, start the GUI, appears as joints, makes homing and shows the axes (XYZA).

Now, the blistering problems of stuck jogging the axis in continuous appear again, I have reviewed the INI and HAL files and I think I have everything as before, eliminating the setp pid.N.maxerror .0005, net N-vel-cmd and MAX_OUTPUT = 0 but, I'm learning a lot but something must escape me.

On the other hand the 4 axis there is no way to work as a rotary.

I attach the files to see if any fresh and more experienced mind finds the fault. Thank you
Attachments:

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25 Aug 2019 10:36 #143127 by rodw
Replied by rodw on topic moving problem
In your ini file under [DISPLAY]
try this:
GEOMETRY = xyza

This is what turns on the DRO's

I think there has been a subtle change so watch for errors on the command line. it might need to be xyyza

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25 Aug 2019 11:09 - 25 Aug 2019 11:36 #143131 by RoberCNC
Replied by RoberCNC on topic moving problem
Nothing Rod, its strange, when homing looks fine, inmmediatly the value goes 0 like a rotary but once homed all the A's behaviour is like a linears one.

I think I'll park the 4-axis theme for the moment, I did it as a test and not to have to edit the configuration again. I am much more interested in the problem of jamming and having an operational 3-axis machine. Let's see if PCW appears with its wisdom and sheds light.
Last edit: 25 Aug 2019 11:36 by RoberCNC.

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