5 Axis ParPort Stepper Setup with RTCP

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26 Sep 2015 02:55 #63003 by marq_torque
how i could be dumber ... ?? i didnt remember that i need to "0" the W axis before i get to work... :) so everything is fine just ...

ok so main problem is i need to break link with C when it rotates 180degree other movements are strange ... :dry:

now trying to figure out which lines affecting it ...

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17 Sep 2017 13:32 #99056 by marq_torque
Hello Members,


After long long time i am back some routine struggle and all, at present working on machine. did setup everything on machine physically and now trying to configure linux, as expected stuck at kinematics, here is situation

1) I learned to configure step axis, and configured all axis and its live and working as expected. tried jogging in world and joint mode no any errors nothing

2) i tried to install latest kinematic file, but its throwing error with joint 3 follow error, and even if federate in this latest kinematic is very slow this throws error and installed old kinematic which i attached in this thread previously, now problem is its jogging and switching without any errors but main problem started showing when i started moving w axis, it started moving in Y axis which is not present in my machine as its only rotary head with B axis and C axis is rotary table. now scratching head where i gone wrong. i havent had tested W axis movement before only tested b axis rotation and it was working fine.

any help ?

attached here old kinematic which is running smoothly without any errors,

and latest kinematic file from dev folder. any help much appreciated.

marq
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17 Sep 2017 13:47 #99057 by marq_torque
These are differences between Latest Kinematic and old kinematic if anyone could save me please?


Ankit
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17 Sep 2017 20:01 #99067 by andypugh
I think that any RTCP machine will always have a Y axis.
The XYZ coordinates define a position in space and the machine joints move to accomodate that.
Unless you live in flatland , every position in space is defined by XYZ. :-)

Which version of LinuxCNC are you using?

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18 Sep 2017 04:16 #99073 by marq_torque
Hello Andy,

Thanks for response, I am using 2.7.11
i have found one thing that modifying kinematics to remove link between C axis and Head rotation works fine, but it need to modify for this Y axis movement, when issued W axis move, Y axis moves automatically to that W amount, regardless what degree B and C have even in 0 Position of both rotary when i issue W axis command it moves both Z and Y axis. Z is working fine without any problem as it should, but Y is moving which should not, now thats causing me real problem because i am on the way to setup head type 4th axis Router with W axis. dont know what to modify in kinematics. !

Ankit

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18 Sep 2017 06:32 #99075 by andypugh
Possibly you need to reconsider what RTCP means?

It may be that this page in the docs helps to explain it.
linuxcnc.org/docs/devel/html/motion/5-axis-kinematics.html

I think that you might be confused about the the difference between axes and joints. (which is understandable, because LinuxCNC 2.7 is confused about the difference too). 2.8 will make the distinction much clearer, that documentation link above is actually to the 2.8 (development) version of the documentation.

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19 Sep 2017 14:14 #99121 by marq_torque
You Sir,

Very true, i studied and studied last time also. but now i found solution to 4th axis head router is to configure all 5 axis as per sample and leave c axis 0 from cam processor and thats it. but now i am curious that what is difference in Old Kinematics and new kinematics as seen in my previous post with screenshot and red marking i am noob to understand. can you help me ? :)

thanks
Ankit

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21 Dec 2017 12:10 #103427 by marq_torque
Hello Andy
Update : Everything working good except one thing. Is when I command head to move forward or reverse. It completes motion overshoots and comes back to position especially at higher feed. When feed is low there jump but not measurable it requires one program to test on workpiece. Can you explain what m I missing here

Second thing is I want to use G38.2 to adopt tool length difference in W tool offset. I am tired of fiddling with. But this command seems useless for tool height touch sensor. When I command w axis to move forward to touch probe. It touches and stops motion. But getting values in opposite
For example I have command w to move -100 it finished touch at -80 now if I add -80 in tool offset its wrong because it's 100-80=20 so how to add this subtract function? And thing is I need to be at specific Z co-ordinate as a start point for probe move. Or else pivot distance will not be calculated. Now I am pulling my hairs.

Pardon my English

Any help ?

Thanks
Ankit

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21 Dec 2017 13:55 #103429 by andypugh

Hello Andy
Update : Everything working good except one thing. Is when I command head to move forward or reverse. It completes motion overshoots and comes back to position especially at higher feed.


I think I recognise this problem.
I think that you get this when [TRAJ]DEFAULT_ACCELERATION is not set
linuxcnc.org/docs/2.7/html/config/ini-config.html#_traj_section

Though it could also be bad PID tuning.

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22 Dec 2017 08:14 #103456 by marq_torque
Thanks Andy,

Thing is i am running Pulse Sign Configuration so PID Tuning in EMC make any difference ?
second, i read this

"DEFAULT_ACCELERATION = 2.0 - In machines with nontrivial kinematics, the acceleration used for "teleop" (Cartesian space) jogs, in machine units per second per second. "

So isn't it effective for jog move only ? While in my setup jog move it does same as MDI command.

Any help regarding tool offset ? I have Er25 Collet dircet drive spindle so changing all time tools. not the holder so i cant measure tool length all time.


Ankit

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