Rotary axis relative to offset

Hi,

Is it possible to make AXIS to draw 4th axis toolpaths around offset coordinates rather than around absolute YZ zero?
At the moment I have the following in .ini:

[DISPLAY]
...
GEOMETRY = AXYZ

[TRAJ]
AXES = 4
COORDINATES = A X Y Z

When I jog A axis it always moves around the absolute Y and Z zero coordinates rather then around Y and Z zero coordinates set with touchoff or G92.
My rotary axis is not fixed to the machine so whenever I install it on the machine the absolute Y position is different so unless I change absolute Y zero in .ini every time the toolpaths are not displayed correctly. Toolpaths look like this:

kajukcnc wrote: Is it possible to make AXIS to draw 4th axis toolpaths around offset coordinates rather than around absolute YZ zero?

Unfortunately not.
The problem is that there is no way for Axis to know where you want the centre of rotation to be.

If you want to preview machine movement then you could consider setting up a Vismach model of your specific machine. But that is a fair bit of work.

andypugh wrote: Unfortunately not.
The problem is that there is no way for Axis to know where you want the centre of rotation to be.

Thank you, I understand now it is not possible (spent days trying to figure out how to do it) but out of curiosity aren't we're telling Axis using Y and Z touchoffs where we want the centre of rotation to be?

kajukcnc wrote: out of curiosity aren't we're telling Axis using Y and Z touchoffs where we want the centre of rotation to be?

Not necessarily. Consider the situation where the centre of rotation is at the machine zero, but the touch-off is to the surface of the work (engraving on the surface of a cylinder, for example).
The centre of rotation will always be machine zero on some machines, it may be relative zero on some others, and an many it will be neither.

Is it possible (difficult) to add a function to Axis which, like touchoffs, sets centres of rotation for ABC axises?

kajukcnc wrote: Is it possible (difficult) to add a function to Axis which, like touchoffs, sets centres of rotation for ABC axises?

It should be possible, and it is probably all in Pythin code, so you can make changes as they will work without recompiling.

Axis sends the GEOMETRY string to glcanon.py as a variable called "geometry"
I think (but I am not sure) that lib/python/rs274/glcanon.py is where you need to be looking.

Hi,
this topic here is pretty old. Is there a common solution by now?

I just installed a removable rotary axis and recognized, that the center of rotation is the machine orgin, not where it acutually is.

I'm wondering: what is the common way to do this?
* Shouldn't the WCS always be in the center of the rotary axis? Can I enforce it to be?
* How can I touchoff my rotary axis in order to tell axis - well here is the rotational origin

Thanks a lot
BTW my version of linux cnc is pretty old, too (from 2015). If there is a solution, please tell me which version I need.
Schorsch

As far as I know there is no solution.
It isn't a huge problem in some ways, you can still use the preview to see what is going on, it just won't necessarily be scaled correctly.