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Tilted work plane milling G68.2. Fanuc Robodrill

caluche123

Plastic
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Jan 29, 2021
I am working with a Fanuc Robodrill equipped with a rotary table (4 and 5 axis) and I have to mill a part taking into account that this milling must be performed along the perpendicular direction of the flat upper surface of the part. In order to do it, The machine is equipped with Renishaw inspecton probe with the objective of capturing the real angle around the X and Y axes. After getting those angles we would like to compensate them with the objective of getting said perpendicularity during the machining. I am using the G68.2 but i am not getting good results.

I am using the following code "G68.2X0Y0Z0I#953J#954K-90" where #953 is the angle read by the probe around the X axis and #954 is the angle read by the probe around the Y axis.

Is there anything wrong? Should I compensate those angles by using another code?

I would really appreciate if someone could give me an idea of what I am doing wrong.

Thank you very much.
 
G68.2 uses the kinematics parameters #19700-#19705. The center of rotation of your A and B rotaries should be in those parameters. Then, you should be able to probe the two angles in X and Y and store the angles in your G54. Activate G54 and probe your part for the program datum. Then, G68.2 should work as described.

Another way is to use Workpiece Setting Error Compensation (G54.4). But that is a paid option and most MTB's don't give that as standard.
 
G68.2 uses the kinematics parameters #19700-#19705. The center of rotation of your A and B rotaries should be in those parameters. Then, you should be able to probe the two angles in X and Y and store the angles in your G54. Activate G54 and probe your part for the program datum. Then, G68.2 should work as described.

Another way is to use Workpiece Setting Error Compensation (G54.4). But that is a paid option and most MTB's don't give that as standard.

Thank you for your reply, I will check it on monday.
 
G68.2 uses the kinematics parameters #19700-#19705. The center of rotation of your A and B rotaries should be in those parameters. Then, you should be able to probe the two angles in X and Y and store the angles in your G54. Activate G54 and probe your part for the program datum. Then, G68.2 should work as described.

Another way is to use Workpiece Setting Error Compensation (G54.4). But that is a paid option and most MTB's don't give that as standard.

Hello

We have used Axiset to calculate those parameters and there is no change on the results obtained. Upper surface is still not aligned :bawling:
 
Would it be possible for you to share a photo or drawing of what you're trying to do? It sounds like it should be doable with G68.2, but you might need a specific definition to make it work. If I'm understanding right, the "roll, pitch, yaw" method may work if you know exactly what you need to rotate around.

As you may or may not be aware, here are the different options for defining a tilted plane with G68.2:

G68.2 P0 - Eulerian Angles (same as when P0 is omitted)
G68.2 P1 - Roll, pitch, yaw
G68.2 P2 - 3 points in a plane
G68.2 P3 - Using 2 vectors
G68.2 P4 - Using Projection Vectors

I personally have only ever used P0 and P1. But the other 3 give you ways to define the plane with different sets of data. The trick is of course how to come up with that data.

Another option, Renishaw macros have cycles for "leveling" rotary axes with 2 points. Cycle 9818 on Mazaks, not sure if it's different on a Robodrill. That is generally what I do with a workpiece to tram it square to the machine axes. You may be overcomplicating things trying to use G68.2, but it's hard to tell without visuals.
 
Would it be possible for you to share a photo or drawing of what you're trying to do? It sounds like it should be doable with G68.2, but you might need a specific definition to make it work. If I'm understanding right, the "roll, pitch, yaw" method may work if you know exactly what you need to rotate around.

As you may or may not be aware, here are the different options for defining a tilted plane with G68.2:

G68.2 P0 - Eulerian Angles (same as when P0 is omitted)
G68.2 P1 - Roll, pitch, yaw
G68.2 P2 - 3 points in a plane
G68.2 P3 - Using 2 vectors
G68.2 P4 - Using Projection Vectors

I personally have only ever used P0 and P1. But the other 3 give you ways to define the plane with different sets of data. The trick is of course how to come up with that data.

Another option, Renishaw macros have cycles for "leveling" rotary axes with 2 points. Cycle 9818 on Mazaks, not sure if it's different on a Robodrill. That is generally what I do with a workpiece to tram it square to the machine axes. You may be overcomplicating things trying to use G68.2, but it's hard to tell without visuals.



I am using the cycle O9818 as well but the output given by the probe is the angle correction, the Z difference and the axis position. I am assuming that I have to use the angle correction to compensate the initial G68.2 (I tried P0 and P! and it did not work) but maybe it is not correct at all. Should I use the axis position? If so, How should I use it?
Tomorrow I will try to share some photos.
 
You would use 9818 to update your work offset with the rotary location. That would straighten the part to a given axis, the same as indicating that surface to make it parallel to X or Y.
 
If you are trying to level the part using both the 4th and 5th axis then using O9818 wont work as it will only level the part in one axis.
Renishaw do offer and an advanced cycles package that contains a 3 point levelling cycle that rotates both the 4th and 5th axis to level the part.
 








 
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