Machine Screw & Bolt Clearance Hole Size

You are bolting two pieces of material together and require a hole in the materials, of the correct diameter, in order to insert the machine bolt or machine screw, as shown in Figure 1. The question is what size drill bit will make the correct size clearance hole?

Figure 1 - Machine screws

Table 1 provides the correct drill bit size, in order to create a hole for the most common sizes of machine bolts. Drill bit sizes are provided for both tight and free fit.