Abstract: An extension assembly increases the safety of bench or table-type machines without significantly reducing the mobility of the machines. The extension assembly includes an extension table, rigidly connected to a support surface of the machine, and a longitudinally adjustable support element connecting the extension table to the body of the machine. A self-adjust mechanism is provided which facilitates adjustment of the extension table of the extension assembly upon adjustment of the support surface. The self-adjust mechanism preferably includes a spring biasing inner and outer telescoping tubes of the extension assembly. Leveling assemblies may be mounted on the machine to increase its stability.