Seconding drewd. But make sure to use rated threaded rod for the studs, either B7 or grade 5 material at the Minimum, And heavy nuts on the top. The last motor I put together had M8x1.25 threads at the top (standard) and M8x1.0 fine threads where it mates with the cases. Big no-no on the designer's part, because grade 5 M8x1.0 allthread is next to impossible to find. I'm having to use bolts and cross my fingers.
Also, for studs, use Red loctite to mate them to the cases, better than JBweld. blue loctite if you ever have to remove something, red for a near welded bond.