My dad used a 7" two-speed Craftsman grinder for most of his rough work. It would strip paint like nobodies business, and knock the layers of bondo down to speed things up over using a rough file or grater. I still have his 7" grinder as well as the 4" Craftsman grinder he used for dressing welds down. Have had to put new cords on them but they are still working well on my 73 Cuda restoration.