Electrical Wiring

First, apologize in advance for the length of my question. I have a 30 amp 220 volt circuit running to my garage. I'd like to be able to power a 30 amp 220 volt garage heater and some of my woodworking equipment (lathe, dust collector, table saw, etc., all of which are 220 volts) from the single 30 amp plug - but not at the same time. My plan is to remove the 30 amp receptacle and install a 30 amp heavy duty double-pole double-throw center-off maintained contact toggle switch in its place. Then one side of the switch would be hard wired to the garage heater and the other side would be wired to a new 30 amp receptacle. I would then buy a 30 amp plug and some wire to connect to a handy box that would have two 20 amp wires/plugs coming out of it. That way, I could power my lathe (15 amp) and dust collector (7.5 amp) at the same time. So, switch up powers the heater, switch down powers the handy box, switch center shuts all power off. When in the down position, I would never exceed 30 amps on the circuit. My question is whether I would risk any damage to my equipment using the configuration I've described. Thanks in advance for your thoughts.