I use my router everyday to engrave hardwoods with perfect results. For this I typically use a traditional v bit,  either 30 or 60 degree pencil tip. 
The plaques I have been having issues with are 7mm x 25mm in size with text around 3mm - 10mm. The material is abs plastic with a metallic coating. I have been using a single flute solid carbide cutter, with a 30 degree and 0.235mm flat tip.
The results I am getting are quite poor. There is a lot of scalloping to the text, despite only using an 8% stepover.
Is the machine I am using just not good enough?
    				
    				
    				
    				
    				
    				
    				
    				    					    				
    				    			