Milling Machine. When you think of Bolton Tool's milling machines, you think of high quality mills at very low prices. We at Bolton Tools are known for our impressive quality mill/drill machine tools. We guarantee our milling machines will be the best value on the market, HANDS DOWN! We take great pride in the workmanship of our milling machines.
The strength and type of steel used in a bolt is supposed to be indicated by a raised mark on the head of the bolt. The type of mark depends on the standard to which the bolt was manufactured. Most often, bolts used in machinery are made to SAE standard J429, and bolts used in structures are made to various ASTM standards.