Improving resolution of finishing.

I have just started to use Carveco maker and my first 3D carve was a little disappointing. The images below show the model (from the 3D relief library) and the simulation. I used a 1/4" square endmill bit for roughing and a 1/8" ball ended bit for finishing. I expected a much finer finish.

Multiple Z passes required 234 hours to refine the piece and I settled for a single pass of the finishing tool to keep the machine time to 1 hour and 15 minutes. The final image is an olive wood block with the relief model carved into it. I think the block was slightly damp from the supplier so the cutting created a lot of string... almost like pine. Not ideal for a good finish anyhow. My previous carving of olive wood was very successful. 

My question is what can I try to further refine my carved images. I do have a 1/16" ball ended cutter as well. I did not want to really increase the machining time by too much time. Any suggestions for obtaining a better finish with reasonable machining times and cutters that provide reasonable material removal rates would be very much appreciated. Thank you.

much appreciated.