I'm writing GCode to cut a polygon with several arcs in it. In one place, three arcs follow one after the other and Mach shows an error reading the block for the third arc with the "Radius to end of arc differs from radius to start" error message on that block. I did discover a small error in the original CAD drawing and corrected that and adjusted the GCode, but the error still happens.
I am using the SIN, COS and ARCTAN trig functions in Mach to calculate the parameters in the GCode. When I single step through the code in Mach, I note that when I come to the part with the three arcs the DRO readings start to deviate from what they should be - based on the co-ordinates from the CAD program (AutoCAD LT) and my checking the calculations with my HP35s calculator.
Start of first arc
DRO readings 33.1302,30.8210
Start of second arc
DRO readings 34.3560, 31.6840
CAD co-ords 34.3560, 31.6848
HP35s results 34.3560, 31.6848
Start of third arc
DRO readings 40.3720, 28.9010
CAD co-ords 40.3731, 28.9013
HP35s results 40.3731, 28.90136
The next point at the end of the third arc is a hard reference from a fixed point, so it looks as though Mach is throwing an error with a deviation of 0.0011 in X and 0.0003 in Y at the start position
Am I pushing the accuracy of the Mach trig functions too much?
I've also tried switching between incremental and absolute IJ working, but with no change.
Any suggestions?
Jim.