# Thread: Rotary Axis Shift Help

1. ## Rotary Axis Shift Help

I am having an issue figuring out how to shift a rotary axis from the zero position. I need to move my rotary axis -4 inches in the y and 7 inches in the z axis relative from zero.

My machine is a 5 axis XYZBC with the C axis on a table and the B axis on the head.I am trying to move the B axis relative to the C. I have the primary set as the C axis and the B axis is secondary. I am using Mastercam X4.

Thanks,
Andrew

2. I still can not figure out my issue. A simpler way of saying this is that when my B axis moves it tilts the table. When this happens it changes the y and z position so my tool is not going to go in the right position. I need to be able to correct the losses in the y and z.

Any help is useful ,
Thanks

3. How do you know it's the wrong position? Did you calculate the 5 axis position for a ball end mill, on a dual pivot machine?

Mike Mattera

4. Are you using the machine as a 3+2 positioning or as a full 5 axis

if as a 3+2 , did you set the origin point in the view manager, it should have sone reference to the WCS you use

if as full 5-axis, does your machine have RTCP ? ( knows where the tool tip is at all times )

or have you not set the WCS to be common on all operations for the setup, T/C planes would then have a refeence back to B0. C0.

5. For Mike: I know it is wrong because we were doing dry runs with the machine. I would zero the machine at the zero position (center of rotation of the c-axis) with the tool tip.Then I would run the code. Everything moves in the right direction axis wise I just can not get the machine to correct for the changes in the tilt table when the B axis moves. My tool is not located centerline of the rotary axis, it is offset, located on a tooling plate connected to the B axis.

I am not sure if I need to insert some sort of transformation matrix to account for this in the post or if there is a just an area I insert a value. It could also be that Mastercam thinks my axis intersect at 0,0,0 when really they do not. I am not sure exactly how to change that.

For Superman,

I am using it as a full 5 axis. My machine does not have RTCP. I have my WCS located at the center of C axis rotation (top view). My T/C planes are located at the same place.

One thing you should know is that we are using 5 axis projection for most applications. So we will follow the path that I tell it to go.

The tool seems to follow the right shape it is just offset from the correct starting position. The code seems like it would be correct if we had the B axis rotating the part instead of the spindle and the spindle only in the Z direction.

Thanks for responding guys, do you have any suggestions that may help.

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