CNC Mill Mark Removal in Intake Port

What I did this morning with the cartridge roll took 15 minutes for 1 port and was almost foolproof. Sandpaper is just not that aggressive. If Joe average put a little Gorilla tape over the valve seats to protect them and was careful with the sander, there is no reason a 60 grit or 36 grit finish could not be done at home. The carbide burr is a different animal. It can get away from you and do damage very quickly. Best left to the professionals. I'm not advocating the sanded finish, just saying it's an option for us average guys where the burr finish is not.

I still want to sand the SSR to a smoother finish just to see what it does on the bench.

Thanks for all the input. What a great group of responses.