how to split a 40" model into 5 parts to print seperate
You've got several options:

Generate full-size STL, cut via software later

If you just have an STL, you can use software such as Meshmixer to modify it. In this case, a plain plane cut would suffice.

Modifiy the design file

A better way is to go into the design file (in your case fusion) and modify it there. In your case, it's rather easy:


add a construction plane


choose the right constraints, e.g. an angle to the XZ plane or a distance to the XY plane

choose the model


Edit &gt; split model
choose the construction plane you made

rinse and repeat


If you want to get rid of parts that became superfluous after this, use the remove option, not the delete option, as the later tries to make sure that the object never was made in the workflow.