Regarding UVW as axis 6,7, and 8

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06 Jul 2019 14:01 - 06 Jul 2019 14:02 #138736 by GaryLa
I have seen many mentions of UVW being "arbitrarily-assignable".

I have also seen many mentions of them being considered "parallel" to XYZ. Is this for the sake of displays?

I am trying to conceive some automation projects in my shop and would love to have 3 more axes that I could utilize independently from my use of XYZABC.

For example, I have a bunch of parts to make for a project. I would like to first build a little part-loader and activate it similar to how M6 is used for a tool change.

I like the idea of having UVW -- via GCode -- to drive this part changer.

Can UVW truly be used as 3 "arbitrarily-assigned" axes driven by GCode without having any affect on XYZ ?

Thanks in advance.
Last edit: 06 Jul 2019 14:02 by GaryLa. Reason: Typo

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06 Jul 2019 14:36 #138738 by pl7i92
Hi
linuxcnc
is PID orientaded
so you can also have a NON Axis letter Joiunt
moving by gcode
saying M150 Palet 0 in
M151 pallet 1 in
...
behind the Mcode is a simple Gcode that moves the changer

but you can also configure 9 Iso axis and only show 3 xyz
there are many things idees you can go with

you may also look on YT linuxcnc pallet changer

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12 Jul 2019 11:40 #139163 by andypugh

GaryLa wrote: Can UVW truly be used as 3 "arbitrarily-assigned" axes driven by GCode without having any affect on XYZ ?.


Yes, normally you can do anything you want with UVW and the commanded value will appear on the joint.N.motor-pos-cmd pins, corrected for homing offsets, backlash and any UVW offsets in the tool table.

Some Kinematics might do special things with them, W as a tool length is not unknown in 5/6 axis configs.
But for trivkins they can point in any direction without penalty.
The following user(s) said Thank You: GaryLa

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13 Jul 2019 12:28 - 13 Jul 2019 12:36 #139247 by GaryLa
Thanks for the answers. I was with you up until you wrote, "trivkins".

Is "trivkins" refering to the typical operating mode most people use or is this a mode I need to use in order to use UVW as I mentioned?

I have seen the word "trivkin" many times before, but I never really looked into what it exactly meant.
Last edit: 13 Jul 2019 12:36 by GaryLa.

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13 Jul 2019 13:00 - 13 Jul 2019 13:00 #139248 by andypugh

GaryLa wrote: Thanks for the answers. I was with you up until you wrote, "trivkins".


Every LinuxCNC config uses a kinematics module. It converts the XYZABCUVW G-code commands into motor positions.
For something like an industrial robot, or a Stewart Platform there is quite a lot of mathematics involved in the calculations.
For a typical machine tool there is none, X => motor 0, Y => motor 1 and that is all there is to it.
For such machines the HAL file will contain "loadrt trivkins". Trivkins is the simplest of the kinematics modules (trivial kinematics) and is one that allows you to control motors completely freely and independently.
If you don't know what kinematics your config is using it is probably using trivkins.
Last edit: 13 Jul 2019 13:00 by andypugh.
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13 Jul 2019 15:51 #139261 by GaryLa
You are right, of course.

I was hoping as much, as I've finished with the part loader and can't wait to run it.

I had also been thinking of possibly using 2 different LinuxCNC boxes and tying them together with a simple I/O handshake using M codes to perform the I/O.

Using UVW is better.

Thanks again!

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13 Jul 2019 17:27 #139264 by andypugh
One advantage of UV~W is that they can be part of the homing sequence.
There is a development of LinuxCNC that has a way to add "extra joints" that are not controlled by G-code words but still partake in the homing process.
github.com/LinuxCNC/linuxcnc/commit/542a...0ceb89fe050ead6d25e7
But that is not yet in any released version.

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