Is it possible to make shallow length cuts with miter saw?

Hi, I just bought the dewalt DHS790AT2 flexvolt miter saw and was going to build a greenhouse for my 1st project.  The plans for the greenhouse require a 1.5″ deep x 3.5″ long cut on 4x4x8 & 10′  for the base.  I’m new to this so was wondering if it’s possible to make this type of shallow sweeping cut like this or if I need to make several cuts up to this length.

Is there a trick to this or would I need a jig saw to accomplish this task?

 

Thanks,

 

Art

The saw features a trench cut set up.  It should be just a thumb screw with a plate you flip over so it’s always the same depth. 

 

If I am understanding it right, you just need a a 1-1/2″ deep into the 4×4 that is 3-1/2″ long.  Yes you can set that up on your saw.  Just make a cut on each side of the 3-1/2″ and you can chisel the middle out.