With professional and productive factory, HAINAISEN is one of the leading China steel tooth bit manufacturers. Welcome to wholesale steel tooth bit from us, we always have cheap products to offer you. Method of operation 1 measurements of good size, matching the corresponding joint. 2 well check each bit roller flexibility, loose or not, connection of drilling tools. 3 to the bottom, the rotating disk, to be smooth, then slowly down, all the sand flushing as well. Gradually add pressure to 4 bit, the intensity should not be too large, otherwise the bit may lead to deformation or wheel fall off slowly. 5 drilling speed must be just perfect, drilling cement fifty to seventy drill more appropriate. http://www.pdcoiltool.com