The part of the vibratory tamper that takes the most abuse is the base plate. In the market, you will find two types: fabricated steel and ductile iron (nodular cast iron). Fabricated plates are made of bent and welded steel; they are cheaper but prone to cracking at the weld points under harmonic stress. Ductile iron base plates, on the other hand, are cast as a single piece. They offer superior "travel" because they are naturally heavier and smoother, and they resist the abrasive wear of crushed granite or limestone much longer. When I’m reviewing gear for a paving contractor, I always recommend the cast iron base. It provides a more uniform distribution of the centrifugal force and acts as a better heat sink when working on hot asphalt.
