Why need PDF and STP two drawings for CNC machining ?

Why factory always request PDF and STP two drawings when start to produce ?

This is very easy to answer : becasue for CNC machining , we always need STP files to make program . then debug machine .

For the PDF files , when we inspection , we need according the PDF tolerance to inspect it ,ensure all size is correct .

If you only design STP files , no PDF , you can tell us the tolerance , then we will according your request to do it .

More tolerance standrad , you can see our CNC machining page :

ISO 2768 Tolerances

About the drawings , just make a refer for you :

PDF

STP