[PoppaJim]

Hi - hoping for some guidance on setting up an ABB IRB120 for Milling. Did my first test by milling a simple 100mm circle in some foam. The curve was generated in Fusion. Everything works well except there seems to be a calibration issue: The circle is 5mm different on the X Y plane.  I thought maybe I should recalibrate the Robot and did that no change. So I am assuming that the issue is in calibrating Robodk to the real world - the base frame. Can find any references for doing that. Can someone point me in the right direction, please?

[Albert]

We need more information to better help you:

1. Can you share your RoboDK project?
   
2. Where do you see these errors?
   
3. How did you calibrate the tool and coordinate system?
   
4. If you bring your robot to all joints at the 0 position, do you see the robot within the joint markers? Each joint has a marker/slot that shows the 0 position, otherwise, you can update the revolution counters at this position.
   

[PoppaJim]

We need more information to better help you:

1. Can you share your RoboDK project?
   
2. Where do you see these errors?
   
3. How did you calibrate the tool and coordinate system?
   
4. If you bring your robot to all joints at the 0 position, do you see the robot within the joint markers? Each joint has a marker/slot that shows the 0 position, otherwise, you can update the revolution counters at this position.
   

Thanks for that Albert - project attached.

The distortion is evident when you run on the robot - measuring a curve's actual size against the path size. 

I Calibrated by re-zeroing all axis and updating the rev counters with the markers in the correct position as you describe.

[Albert]

How did you calibrate your tool?
Can you share the RDK project?

[PoppaJim]

How did you calibrate your tool?
Can you share the RDK project?

Ok I think the issue is the calibration. I recalibrated the joints and reset the rev counters but I gather I need to calibrate to the base planes as well? The distortion seems to come from the Z plane not being verticle. Whats the best way to fix that? Calibrate reference ?

[Albert]

Once you update your revolution counters you should teach your coordinate systems again.

If you defined your coordinate system using 3 points with the robot, the plane will not be accurate and it would explain the errors you see.

[PoppaJim]

Once you update your revolution counters you should teach your coordinate systems again.

If you defined your coordinate system using 3 points with the robot, the plane will not be accurate and it would explain the errors you see.

Hi again! Going back to this thread as I still have the same issue. I have recalibrated the base frame after updating rev counters as you suggested but I am still getting the same discrepancy! Its driving me nuts. Any suggestions are appreciated.

[Albert]

Did you update your revolution counters properly? This helps the robot remember where the joint "zero" position is.

Once the revolution counter update has been properly done, can you move the robot to the home position (all joints at zero), and take a picture of the slot marks on each joint that show the zero position? It should be within the marks.

Please note that if the robot does not have battery left and you reboot your controller you lost this revolution counter update (there is a small battery in the robot arm to remember the revolution counters).