Mazak 5 axis mill with tool center point control g43.4

Hello all,

I have what seems to be a lack of understanding of the two coordinate system options when using G43.4 on a 5 axis mazak mill (specifically this is one of the new VCU mazak machines with B and C axes). According to the manual, G43.4 can be used where x,y,z are given in a table coordinate system, where the x,y,z values are always relative to the part, in other words the coordinates are given assuming you are viewing them as if you are sitting on the part and rotating with the c axis (this is with F85 bit 2 set to 0). The other option is to program in a work piece coordiante, where x,y,z are specified in a fixed orientation (F85 bit 2 set to 1), as viewed if you were standing outside the machine. I have a really great postprocessor for my Integrex machine, which uses the second option, so i am trying to make use of that for my new 5 axis mill as well. I have made all the required post changes and everything is working great, except for full 5 axis simultaneous axis cutting using G43.4.

I have tried some simple tests that are making me think i am missing something with regards to how G43.4 is supposed to make the machine move. I will describe what i am seeing and would ask that anyone who understands these functions please help explain this to me more clearly.

I set a workoffset to some location on my machine (not table center) that is just above the top of my work piece. I turn on G43.4 then move the tool to x0y0z0. Then i rotate the tilt axis, B, to B45.

In table coordinates (F85 bit 2 = 0), the machine moves x and z while rotating B such that the tool tip always stays just off my part. This is exactly how i expect tool center control to behave.

Now here is where i am getting lost. When i switch to work piece coordinates (F85 bit 2= 1), i get a significantly different motion. I had to stop the machine immediately because the tool was heading right into my part. I bumped up the work offset so i could see what was happening and X and Z appear to actually be going in the opposite direction as they were in the previous case. So my tool tip is not pivoting relative to the work piece in any way that i can understand. From what i can gather from reading the manual, the differences in table/workpiece coordinates should really only effect the motion due to c axis rotation, not b axis rotation. Am i missing something? Is this an error in the control? Mazak has been pointing me toward using G54.2, but this would require a complete post rewrite and would require my tool path be broken into very small sgments, which i would prefer not to do. Any info that can help me understand this better would be greatly appreciated. Thanks.

-Kevin

It is amazing how little truly good 5 axis info there is, especially regarding TCP. If you never got this one answered, I can answer this one.

I don't know if the original poster got an answer, but I have a similar situation & would like to know the answer.