There have been many questions I've seen in the Handibot forums about cutting speeds for different materials. Below you'll find a link to a chart I created to track some of the successful feeds and speeds that have worked out.
Nailing down just the right speed can be difficult, and it's different for every project. Then there is how many pass depths, and step-over. I've tracked everything that's worked for me here. Consider this a starting point for your next project. If you want to submit your own successful speed and feed do so with the link below and I'll add it to the list.