Purchased to cut the bottom of the filter port in an espresso machine. I have an old Simonelli with an e61 group head. He removed the spout at the bottom of the filter in a vise. This cutter had a guide nozzle in the center to help position the cut. Are those portafilters solid brass? But the router came through cleanly with just a Makita cordless drill. Modifying an old portafilter in this way was a lot cheaper than buying a new bottomless portafilter and this modification got rid of the worst stains in the old filter.