Don't see what you need? Hexagonal heads and machine threads used with a nut or in a tapped hole; also known as or machine bolts. Hex bolts are similar to hex cap screws.What is the difference between a hex cap screw and a hex bolt? A hex cap screw has tighter tolerances on the body dimensions and features a chamfered end and a washer face under the bolt head. A hex cap screw is often called a finished hex bolt. Hex bolts have a flat end and lack the washer face under the head. Hex bolts may have an undersize body in longer lengths.