Wood & Bit type for 3D puzzles

I finally got my CNC machine up & running properly.
I cut a 3D puzzle of a small dump truck.
I used 1/4" plywood. I figured oak would be the best, but the small pieces didnt cut great. Some pieces had layers of the wood flake off.

I'm using the following tool:
F32065 Fullerton Carbide End Mill 1/8" 2 Flute Regular Single End

I should also mention that my CNC uses a rotozip

Is this the correct tool & wood to use?
thanks
jason