This system will not be perfect without the use of slow rotation air drill. SP802 is made of hard steel which will produce a lot of heat when it grinds and cuts the spotweld which is also very hard and tough. The heat produced will burn and damage the cutter if used continuously. To reduce the heat and protect the cutter, low speed air drill should always be used. SD800 only provides maximum rotation speed of 800 R.P.M. This gives the cutter sufficient room to cool and continue to perform continuously.