Items to Consider:
1.   Size and Weight of Parts to be Welded
    a.   Higher clamping force needed for heavy parts.

2.   Weld Content / Weld Draw
    a.   Depending on the weld content of a joint, and the desired end
          result, heavy clamping force may be required to hold part

3.   Consistency of Parts Being Welded
    a.   Inconsistent parts (flatness, straightness) may require part to
          be formed or straightened prior to welding.