The BX style dog bone and paddle gages operate as functional size “Go / No Go” instruments.
When the dog bone or paddle gage is placed into the seal ring groove on the “Go” side, the gage shall touch the face of the product. When placed on the “No Go” side, the paddle gage should NOT touch the face of the product. There is typically 0.004″ clearance between the paddle gage and face of the part when placed on the “No Go” side. For example, please see the illustrations above and below.
Visually, you are looking for “light” as an indication that the product as passed the “No Go” side. On the “Go” side, you should NOT see any light.