Below is a copy of a program that produces the strange movement.
If I enter a value for the corner radius on our grinding wheel it seems to offset correctly except when moving, it will move Y12 but also moves X  the value of the wheel radius.
If you alter the tool diameter and watch the movement of the Y12 you will see what I mean.
Got me pooched!!.......Can someone please offer some insight?


(strange tapering of parallel movement)
#1=4       ;No of Cuts
#2=400    ;Feedrate
#3=0.05   ;Cut Size
#4=1.      ;Corner Radius on Wheel

#6=[#1*#3] ;(No of Cuts * Depth of Cuts)
G90 G54 G21 G40
G41 G0 X0. Y0. P#4
M1
M98 P1 L[#1-1]
G40
M30



O1
G91 G0 X#3 Y[#3-[#3*2]]
G0 Y-18.
X5.
G1 Y12. F#2 ;Tapers this parallel movement the amount of radius comp that is put on
G2 X1. Y1. I1. J0.
G1 X5. ;Does this line correct (one axis only)
X5. Y5.
G0 X-16.
M99

IS this Mill or Turn code??? YOu mention grinder wheel radius.

(;-) TP

Oh, sorry forgot to mention, mill code, it's actually used on an XY stage for a tool and cutter.
Very much the same as a router, except uses a grinding wheel, not a cutter.

YOU have alot of things going on at once(;-). YOu may want to move the G41 inside of the SUB. AS is you have the G41 in effect in G90 mode then switch to G91 mode probably confused MACH.

Notice that the the Next G1 move after your G41 is the same line you have taper. Mach needs to have a move to comp the toolpath BEFORE it gets to the start point of the offset and it needs to be at least the same length as the radius you are comping(depending on version) SO it looks like MACH is using the move to comp itself ending up as a taper???



Just some thoughts, (;-) TP

Thanks BR549, but nah still no go.
It's really strange, if I enter G1 Y1 on the line before the G1 Y12. it adds the compensation into that small movement, so I thought I'll just get it to do that on a line earlier in the program.
But if I put it anywhere else it starts doing weird stuff, big circles and so on.
I can only get it to sorta work if I put a Y movement on the line before G1 Y12.
I does the comp correctly, except it comes in then moves out the comp amount, so therefore it would dive into the job, then pull away.
Hmmmmmmmm

YOU can't just add the comp anywhere it has to have a leadin to setup the comp for the cut and usally a leadout to end the comp.  Might want to readup on using comp. It is a simple process BUT can get very complex to program by hand.

(;-) TP

OK I am deciphering your Parametric code I see the shape you are Grinding. WHat exactly is the code suppose to do after the first pass through the code?

(;-) TP

Take a small cut (Value #3) then repeat the cycle until the number of cuts has been completed.
Darc

Take a small cut where? further into the profile?

(;-)

I see the #6 variable calculates a Value BUT I don't see where it is applied??

(;-) TP