Or maybe you found this occours after using your rotary axis.
The problem is: Y movement is incrrect as you set.
For example, in software you set a line of 100mm long along Y axis. the machine moves 200mm or 50mm instead.
Solution (for RDCAM software only):
step 1, go to file, vendor setting:
Step 4: choose Y then press the button showed bellow
Step 5: Input the value you set in software; and input the value you get with your machine, press [write] to send the data into motherboard.
Then you can try again on your mahchine. If the problem solved don't forget to save your current setting as a backup.
You may also watch this video for help.