The only way to reliably export .scdoc files would be to use the original program SpaceClaim in which they were made. The software supports several other formats for output / exchange purposes and apparently it also support SO STEP product data files (.stp, .step).
Convert SpaceClaim 3D CAD document to ISO-10303 STEP product data.
We have found one software suitable in our database for this conversion.
Microsoft Windows software - convert scdoc to step on Windows
A 3D solid modeler for engineers
Convert from scdoc file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.