co-ordinate rotation on a tombstone?

[seven3]

I need a macro to rotate the co-ordinate system as I rotate a tombstone on a 4th axis vmc. I thought it would be farly straightforward but now I,m ready to throw nyself down the stairs!! I did'nt take into account quite what was involved, if the part is not exactly over the center of rotation this affects the output and how in the world do I deal with negative rotational positions?

can anyone please help?

[mfgbydesign]

K&T Gemini controls had an "implied offset" where you could pick up the offset at one index position & the control would compensate X, Y, and Z as the B indexed.
I have yet to see this option available on another control.
You could probably do it with a macro depending on what control you have. I know Kurt does this on their vise bodies as I had to incorporate the macro calls into the programs I wrote for them. Frankly I thought it was huge waste of time as the bodies were all machined on dedicated fixtures and the macro does NOT compensate for machine geometry error.

[dertsap]

you need to set your macro to use the offset position of the x and z from the center of rotation , program header is the best place to add these variables ,
eg:
o00023
(header)
#101= 1.025 (Y offset A0)
#102= -.5 (Z distance between tool probe and part z zero @ A0)
#103= 0 (ANGLE)
#120= -2.525 (SHIFT FROM TOOL PROBE T0 Z0 AT A0 center of rotation)

#103= 90. (rotation)
M97 P8989 (macro sub call)
G52 X-6. Y#109 Z#110
g0 a#103
main program
if your qualifying tools from the top of the part then scratch the toolprobe and set z variable(eg #102) as the distance from the center of rotation
,then you'll need to do some addition , subtraction and a bit of trig in your macro in order to calculate the new rotated position , its not too bad once you get your head wrapped around it


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