the mystery of the wonky corners

[kingcreaky]

By 'meant to be square', do you mean it's meant to be a square, or that the corners are supposed to be sharp?
CORNERS MEANT TO BE SHARP

If its meant to be cutting squares and you get that, then at least part of the problem is the step/mm value in the motor tuning settings has changed...so check those. On your machine it should be the same number on X and Y and two times that number on Z.
BOTH X AND Y STILL SET TO 80


Is the machine loosing position, i.e. does it return to (0,0) when finished? If you suspect it might be a motor stalling, then run the program I made here:

http://www.mycncuk.com/forums/gcode/...or-tuning.html
CANT RUN YOUR PROGRAM AT THE MOMENT BECAUSE IL LOOSE THE POSITION FOR THIS JOB
BUT YES, IT RETURNS TO THE SAME POSITION


If it survives that test without stalling it'll survive pretty much anything, so I'd do it anyway as you've changed the motor settings.

Does it look correct in the tollpath preview in Mach3? Zoom in on the corners...
If you run the program again does it follow the same path?
YES THE MACH TOOLPATH LOOKS OK... ALTHOUGH I CANT WORK OUT HOW TO MOVE THE PANNING POSITION IE (SHIFT AND DRAG, CONTROL AND DRAG) ... I DONT KNOW HOW TO DO EQUIVELANT OF CTRL + DRAG IN VCARVE WITHIN MACH...


SO WHILE WAITING FOR MY KNIGHT IN SHINING ARMOUR... IVE REDUCING THE ACCELERATION RATE OF BOTH x AND Y TO 2500.. NOW IT GOES VERY SLOWLY, IT DOESNT CUT THE INSIDE OF THE CORNER LIKE THE PICTURE SHOWS MY INITIAL RUN DID, BUT IT DOESNT SQUARE THE OUTSIDE OF THOSE TWO CORNERS EITHER.. IT KIND OF CUTS THE CORNER. IM VERY CONFUSED.

[Jonathan]

To pan in the toolpath preview it's either middle click and drag, or right click and drag...I don't remember which it is.

If the acelleration is far too low and you're using G64 (constant speed) mode, then your corners will all get rounded... but it would have to be very low for that to happen. 2500mm/s^2 is pretty high (sure that's not the rapid feedrate). You could try putting G61 at the beginning of the code to force the machine to stop at each co-ordinate precisely.

Where you've tried to cut the slot, parallel to Y, it does look like one of the X motors has lost position and skewed the gantry, causing the subsequent cut to not be parallel to the first. Are the pulleys definitely tight and not slipping on the shafts?

Can you post or send me the code so I can check it?

[kingcreaky]

here you go... thanks for your help buddy

2MM_POCKET_b.txt

[John S]

Not had chance to look at the code yet.

However if you look at the picture it cocks up on opposite corners, assuming the picture is taken from the front of the machine then it barfs out when the Y changes direction so I'd check couplings, pulleys belts etc, anything to do with the Y axis mechanically