set to work (on something)
To undertake a task; to begin working on something. I knew I had to have the report finished by tonight, so I set to work immediately. She set to work on a new design that would reduce emissions from the engine.
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.