Robot follows spinning table CNC

This is sort of out of the left field question, but, I was having a conversation with someone the other day and they said that no matter what they do, the robot arm follows the spinning table when they try to CNC something.
And… let’s say you have a standing figure, the software will not create tool paths till that figure is on its side. (Not sure if this has anything to do with the first part) In any case, it seems to me that if you have a spinning table, the robot arm should be standing in place and only move up and own, not follow the table, because, of course that won’t work for long. Also, if you have a standing figure, it would be easier to CNC on a spinning table while it’s standing.
Any ideas as to why this would be happening?

Sounds like there is an issue in the controller/post processor or potentially the CAM software doing the programming. Can you give some more insight into what CAM software is being ran?

Its very possible to program the robot to do what you are wanting but I cant identify where exactly is issue is without more info - and

Oh goodness… I don’t know anything about it:) All I know is that if the table was spinning like in the 1st video, all would be fine, but the table is on the floor, spinning like in the 2nd video. He mentioned that he thinks there’s a workaround by making the tool-path that rotates around the z-axis. Guess he’s trying to do that now. I just thought I might be helpful:)

That should do the trick, assuming a 4 or 5axis program (basically he needs to run it like a millturn). If it doesnt I would be curious to see what the G-Code looks like and if its being posted properly

Hello Izabela,

Usually, a robot and an external rotary axis are kinematically linked, so that when you turn the turntable, you basically rotate the entire coordinate system. Therefore, the robot also “follows” the rotary axis.
This means that if you want to mill the back of a sculpture as in your example, you actually need to program the toolpaths on the back, and then use the rotary axis to turn the sculpture towards the robot so that it can reach there without colliding with the object. You can of course “unlink” the axis, but I would not recommend doing so.
So from what I’ve read, everything seems to be working as intended and it’s “only” a matter of programming it. In case he’s using KUKA|prc I’m happy to help, but it sounds more like a CAM software to me, in which case it can be a bit more tricky as the robot-specific functions are often not that perfectly integrated.
Compared to a five-axis machine where there is only a single way of reaching a given frame, a seven-axis robotic system gives you infinite possibilities for each position, which complicates things (but also gives you more possibilities!)


Laimis had a quick question: “If the tool path was created using y as a rotating axis (as it seems a lot of software’s are created to only do that), can the robot be adjusted to accommodate that? What I tried was I put -90 the for external axis base, which flipped the x up, but the robot wasn’t rotating correctly. Anyway, I am just curious if there is something that I am missing, or do I just need to create my tool-paths around rotating axis z (which doesn’t give me a lot of options in fact only one option can create that and its called surface tool-paths). Thanks for your help.

Hello Izabela,

The question is slightly tricky as it depends on how you generate your robot code.
Let’s assume that your software generates 5-axis code (e.g. XYZ and AC) and then adds the rotation of the external axis in a next step (as would be the case when using e.g. KUKA SimPro & CAMRob). Creating a local coordinate system where Y is facing upwards shouldn’t be a problem at all. With a KUKA, you create a local coordinate system simply by moving the tool to three points in space: The origin, a point on the X-axis, and a point on the Y-axis.

The system becomes less flexible if you e.g. generate 4-axis G-code (e.g. XYZ and A) and the A is directly mapped to the external axis. If that is the case you’d have to reconfigure your turntable accordingly.

In order to give you more advice, I would to know need some more details on your workflow.