G68.1 Coordinate System Rotation Help

[SwissPR0]

Hello all,

I've been tasked with the challenge to do some angular milling on our Tsugami BH-20, Fanuc 31-i Control Turret Swiss machine.

I haven't done this before, so getting the correct format is mostly what I'm after.

If anyone has any insight, I welcome any suggestions.
Thank you

[PixMan]

Well Dan, it's been a few years since I used that on the Maier ML-32E machines. All I remember clearly is that it didn't make much sense, but it was simpler than it looks. IIRC I used lots of "zeros" for most of the fields, but the "R" value had the angle of rotation.

I'd start with that. Put the R at the angle you need, and on the cancelling G-code, you be sure to put the same angle. I think (not positive) you had to put the R value of the cancelling G69.1 as a negative ( or opposite) of the G68.1, but all the X, Y, Z, I, J, K, except one was zero.

What I do remember clearly is that once you got it rotated around, it worked beautifully. All the offsets carried, everything worked. I did rigid tapping and helical milling while rotated. I think you had to call the offset of the tool into active before executing the G68.1, but you'll gave to play with it. I think there's enough variation in the way Tsugami vs. Maier may have set up the control to be different. I do know that I had done multiple operations and many tools while rotated, so not sure about the tool calls within a G68.1/G69.1 cycle. I looked through my personal files, but couldn't find anything saved. Nuts.

BTW, the Maier machine used a 160iT control. They eventually made the operation a lot easier by creating a pair of custom G-codes to avoid the confusion of entering in all the zeros. In fact, it was me who did that. Damn, why didn't I keep any of that info!

[arobustus]

This thread is more than a year old, but I am at a similar point, so I would appreciate any help. I do have the format correct in that I got past the alarms as begining the move to the start point. However it does not look as if it is moving to the correct place. In fact the trajectory would have sent the B axis into collision with the sub spindle. At that time the word went out to pack up & go home because of the weather. You may have read about the problems we are having in these parts. I put everything back to where the operator could come in next morning and take right off with the job he was working on.
Here is my code for the tool change, approach and retraction. This only faces the part but if I can get this it should be no problem to code the other operations. An idealized picture is located here:
TinyPic - Angular Milling

M79
M25
M143
M51
(MILL 7 DEGREE FLAT)
G28U0
G151G55
T048248(SGS ENDMILL #30834 IN HORIZONTAL)
M6
M81
G0B173.
M82

M50
M241C2
G0C112.5
M142

G97
G99
S6950M203P3
G55

A0
G17
T0
G68.1X.079Z0Y0I0K0J1R173.
T548
G0Y0
X12.
Z.5
X0
Z0
M86
G1Y0F.003
G0Z-.5
T0
G69.1
G0G28U0V0

As you can see I have J=1 because the Z is the axis normal to the part surface. Should it be J-1 maybe?
Thank You!
-plh

[SwissPR0]

What I did find out when I got into this further is there are 2 kinds of G68.1
There is 3D coordinate system conversion, and there is 3D Coordinate system rotation.
The machine came standard with 3d conversion but not coordinate system rotation. We had to call Fanuc and have them install the option for rotation.
There were some more issues after that regarding cancelling the rotation. But when activated, it was working for multiple tools.