I have a file that is in STEP but I need it in SLDPRT. How do I convert the file?

Hello joseph,
What @SolidTweaks and @Carlos J.Veloso say is very true.
However, your query is very pertinent and common among many GrabCad users. For this reason, I offer you a slightly more detailed explanation, which will give you the possibility of doing some research on your own about the "recovery and use" of the information contained in a STEP format.
I am attaching four files that correspond to an example that I just made so that you can observe these issues. Their names are numbered so that you can follow the sequence of the explanation:

1 original SLDPRT.SLDPRT: it is a simple part in which I introduced some sheet metal operations, revolutions, welding, holes and also reference geometries (axis, plane). I suggest you take a good look at its operations tree and imagine that it is the one created by the author of the SolidWorks part that you have, but in STEP format. This is to appreciate later the details of the information that can and cannot be recovered. In this case I used SolidWorks 2017.

2 STEP save from SLDPRT original.STEP: This is simply a save of the original as STEP AP214. This is, perhaps, what the original designer did by saving his source file in this more universal format.

3 SLDPRT save from STEP.SLDPRT - This is what happened to me in SolidWorks 2017 when I opened the STEP format file and saved it as SLDPRT. Note that 3 imported solids were generated for which you do not have an operations tree, although you could edit them.

4 SLDPRT features recognized.SLDPRT: is what arises from one or more attempts to "recognize features" from the INSERT > FEATUREWORKS>RECOGNIZE FEATURES... menu.
This process can be long, complex and frustrating due to the lack of results and even because it usually causes fatal errors in SolidWorks... In my case, after 4 fatal failures, I managed to partially recover the information that you can see in the operations tree . I suggest you pay attention to the geometry that was lost after the recognition, and to the one that was recognized but "not coincident with the original tree".

I hope it helps you understand the problem and, by the way, we can refer to this post when someone else asks the same thing.

Kind regards!