Hi, can anybody convert 3rd party ipt - DWF file to stp?

If you have CAD data in a a DWF file format, it's likely because the original author does not want you to convert it to to something like a STEP file.

The Autodesk DWF format is a highly compressed 3D file format. It's intended as the end-point as far as 3d data goes and is not designed to be converted to other formats. It's similar to a PDF file for 2D data except that it was developed specifically for 3D CAD data. It is touted as a means of sharing 3D design data that cannot be easily reverse engineered and converted to other formats. There are some convoluted workarounds that may work but they're probably not worth the effort.