Need insight from guys use to C-axis programming.

[g-codeguy]

I've done some C-axis programming, but nothing fancy. I have a job that I programmed from the center of a 7/32 inch ball mill. No tool comp. Set-up person has to subtract .109 for Z-axis and .218 for X-axis after touch off.

He didn't even tho it says to in 3 separate places in the header. Okay then, I'll just subtract these values from the program. Easy enough, right? Wrong!

Z-axis works, of course, but the X-axis is close only on the C0 slot. It cuts too much off both sides, tho not equally. The other 3 slots are way off, and, in fact, the 180 slot doesn't cut any chips.

Why??? Obviously I am not understanding something that is basic to those familiar with C-axis programming. As I'm thinking about it, the thought occured to me that maybe I should have added .218 instead of subtracting on the 180 degree slot. Problem is the zero degree slot didn't come out right either.

I modified program back to the original figures, and job is now running. I'd like to understand how to program it from the sides of the tool so the set-up person doesn't have to remember to move the offsets. (I realized too late that I should have left the Zs alone so only X-axis would need an offset. Easy to change, tho.)

[HuFlungDung]

Would it not be a matter of standard course, to set up live tooling so that the centerline of the live axis is the reference for that tool? Otherwise, you'll have to 'pretend program' the feature location farther along the part than it actually is, by the radius of that tool.

As for the depth, you could maybe figure out something from this thread if you don't have access to a CAM program to help you get the depths based on tool tip instead of tool center:
http://www.cnczone.com/forums/showthread.php?t=61238

[g-codeguy]

Mr. Hu, the tool gets touched off on a probe. That is why I was looking to change my program. To avoid extra work for the set-up person.

We have Mastercam. I layed out the part in mill, offset for roughing, defined .218 dia. arcs tangent at a mid-point, analyzed, doubled the X-value, typed values in my program using the Y value for C.