Spot weld cutter

I got 1 whole car out of 2 cheapies I bought on Amazon, but there was learning curve. My best results were if I prick punched a spot for the center pin to ride in and use a old candle for cutting compound. Candles are paraffin. The first one I wore the hole out that the centering pin rides in, I have a few cutters I dulled to the point where they would not cut anymore. I also keep using them if the teeth break off till they just will not work anymore.