I'm really new to the community and got my first machine, the S1 with the 40w laser and added the rotary attachment. I've burned through a couple of tumblers using setting after setting and can't seem to get it to leave clean lines on the stainless steel. I'm trying to engrave Yeti tumblers and it seems to leave a grid like pattern when the power it too high or excess residue. 

Any suggestions for ideal settings? I'd like to go to the highest speed with the rotary so I can complete projects faster, but if slower speed and low power are the way to go, i'll try that out too.