A NOTE FOR BOBCAD-CAM DEV-OFFICE
When a CAD drawing is saved as STL, BobCAD-CAM saves it as binary version of STL.
STL can be in ASCII or Binary format but there is a rule: “A binary STL can never start with ‘solid’ string”.
This because a lot of programs check first bytes of STL file HEADER to check if it is in ASCII o BIN format.
As also wrote in WIKIPEDIA: check STL_(file_format)
Because ASCII STL files can be large, a binary version of STL exists. A binary STL file has an 80-character header that is generally ignored, but should never begin with the ASCII representation of the string solid , as that may lead some software to confuse it with an ASCII STL file.
BobCAD save is with this starting text: solid STL file created by BobCAD-CAM …
which preclude the opening on other software.