Nick’s right - 50% stepover = rough finish, but I’ll be cleaning up with a subsequent waterline cut.
I have possibly the same 300w 24v spindle does 10k rpm max, seems to have an internal regulator as it also does 10k rpm on 48v. I have the performance graphs for it here somewhere and will look them out.
18 hrs seems really high for a .25" project, but caution is wise. Did you do a roughing cut first? I’d expect that to rough out (1/8th") in about 4 hr and parallel/waterline (1/16") finish in about another 3.
I posted a project over in Show & Tell that’s about the same area but 20mm (0.8") deep, that took about 12 hrs. I’m doing a deeper 35mm (~1.4") oval version of it right now, 330mm x 135mm, more detail as it gets lower, 1/8" single flute roughing cut expected to take 15 hrs. And you bet I’ll be going to bed too! Tomorrow I’ll follow with about another 4.5 hrs of waterline and 2.5 hrs parallel using a 1/16th bullnose. That’s 22 hrs all up, but your setup may be quite different.
Again, I’m not sure if that helps…you could post your artwork and I could see what times MeshCam comes up with?