Hi Andy and Stuart thanks for you messages. >> Now I mount the cube on the machine, after touching off it turns out >> that its 0.1 mm off in XYZ and turned and tilted by 0.1°. >> >> How to compensate this misalignment? > > My first guess would be to touch-off the B axis of your coordinate > system to 0.1 degrees and leave the CAM untouched...
That's how I hope or wish things would work. Obviously its not like this. Difficult to say with 0.1° but I did some testes at 20° or so, to see whats going on: The first thing that somewhat difficult for me, is that G54 takes not only B and C offsets, but also rotations around X, Y and Z. The difference is if I enter 10° offset to B and move to g1x0y0z0a0b0 the table is tilted by 10° (as expected). If I enter the 10 as a rotation around Y and move 0 g1x0y0z0a0b0 the table says horizontal, but a move to 100,0,0,0,0 will result in a 10° upward motion of the Y axis (ending at 100,17,0,0,0 in machine coordinates). Now lets assume I use the 'normal' offset method of G54 and dill want to drill holes to each center of the mentioned 10x10x10 cube at machine center but off by B=10°. The hole in the top start at 5,5,10,0,0 perfect. Left and right holes start at 10,5,5,90,0 and 0,5,5,-90,0. Fine, these all worked and are orthogonal to the tilted cube. Now the hole on the front is a problem: The table needs to be tilted and turned. I'd assume it starts at 0,5,0,90,90 but this is not the case. It starts at 0,5,0,80,90. Hmm. Similar problem when using the alternative G54 rotate around axis method. > Depending on your kins this might or might not work. Kinematic is XYZ in the tool, tilt (B around Y) and turn (C around Z, if B=0) table for the workpiece. By the way the problem complex not only bothers me on the Sinumerik controlled mill, but also fora planed 5 axis hot wire cutter which will be LinuxCNC controlled. I think I'm somewhat misunderstanding all the 5axis positioning in milling. For example I always wonder why the xyz workpiece coordinates of the tool tip do not change when I rotate and/or tilt the table. In my understanding I'm rotation the coordinate base, so if the tool is not moving in the machine base coordinate system this is still causing a motion in the workpiece coordinate system. In other words if I'm the workpiece I see the tool move, why do the workpiece coordinate not change? See you Flo ------------------------------------------------------------------------------ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
