cnc 1200 - 1200 mm need help

hello guys am new member
am a 3D architectural designer
i bought a chinise cnc with a table (1200/1200mm) without its own computer
so i bought an computer for it i instaled the driver card correctly and the nc studio too and the machine is working ...
now the problem is when i give it an order to cut a square (150/150mm) ... the machine cut it (120/60mm)
i dont know what to do
any advices ?

That sounds like a problem with your steps per unit settings. You need to increase the steps proportionate to the error until it cuts accurately. If you know the pitch of your screws and the micro-stepping factor of your drives you can calculate it, but trial and error works too.