Which gage is typically used to measure the face reinforcement of a butt joint?

The Cambridge gage is specifically designed for assessing the face reinforcement of a butt joint in welding. This device measures the height of the welding material above the base metal to ensure it conforms to specifications, which is critical for determining the structural integrity and quality of the joint.

Each of the other options serves a distinct purpose: the Tempil™ gage is used to measure the temperature during welding, while the fillet weld gage is tailored for evaluating fillet welds rather than butt joints. Therefore, while all the mentioned gages are relevant in welding contexts, only the Cambridge gage focuses specifically on the face reinforcement of butt joints, making it the most appropriate choice for this particular measurement task.