set (someone or something) to work
To instruct or cause someone or something to begin working or functioning. Janet set us to work cleaning the house while she went and got groceries. I've set the system to work gathering data on all known suspects in the area.
set someone or something to work
to start someone or something working; to cause someone or something to begin functioning. The captain set everyone to work repairing the tears in the fabric of the sails. We will set the machines to work at the regular time.
set to work (on someone or something)
to begin working on someone or something. We have finished questioning Tom, so we will set to work on Fred. We set to work on dinner at noon.