For what purpose would a combination square with a protractor head be used?

A combination square with a protractor head is specifically designed to lay out angles, making it an essential tool for tasks where precise angular measurements are required. The protractor head allows for the measurement of angles from 0 to 180 degrees, facilitating the marking and transferring of these angles onto workpieces. This capability is particularly useful in various trades, including metalworking and carpentry, where accurate angles are crucial for achieving proper alignment and fitment in assemblies.

In contrast, while a combination square can measure lengths or verify squareness through its straightedge and square head features, these functions do not utilize the protractor head specifically. Similarly, checking parallelism would likely involve other tools that more directly address that requirement, such as a ruler or level. Therefore, the primary purpose of a combination square with a protractor head is to provide a reliable means of laying out angles.