Newbie better definition on the edges

Hello, first of all I will apreciate your Help!

I really don't know anything of Moshidraw or Laser engraving, and I bought a cheap laser engraving machine from ebay. I'm pretty happy with the machine that after some adjustment is working.

With Acrilic and wood work perfect, but I need to engrave "aluminium", I was aware that this machine dosen't work with aluminium, but I'm trying to do my best. I bought a can of: LMM14 Thermark, and it works, but I need to know if there is a problem from the file or the machine that the edges isn't so "pure" (I want a better definition on the edges).-

I'm working with Adobe Illustrator CS5 with vectors, then export that vector to a JPG file with the best quality, and then on moshi draw software, from the menu "image" I´m importing that jpg file. and then "Output" with the options from the picture... maybe I'm doing something wrong? Or I don't have to use a JPG? Please help me !! :0)

I'm using Moshidraw left
I also have moshidraw 12, maybe that version it is better??

Picture 1: aluminium with thermark spry
Picture 2: After engraving
Picture 3: Set from moshidraw software
Picture 4: Power

Attached Thumbnails