For really small stuff, I run 25-30mm/sec. The bigger stuff with large sweeping curves I'll run at 50mm/sec. If a print has sharp corners, small changes in direction, I'll run at a max 40mm/sec. This was printed at 45mm/sec...
That'll do it. Try printing one at 40mm/sec and see what you think. I used to print everything at 60. But I have lately been running between 30-40. It makes for much nicer prints. I only use 60 when I don't much care how it looks.
@Addict Rc - Check your belt tension. You can see in the vertical ribs of the cooler, your printer is not handling the changes in direction as well as it should, which is also causing your layer lines that you see in the print.
What speed did you print that at? Printing at higher speeds can...