Maximum grip gaging length and minimum body lengths are important for bolts and screws because they are design measurements that insure that your bolt or screw’s shank and thread lengths have the correct proportion in relationship to its diameter and overall length. Failure to design a bolt or screw with this correct proportion can cause additional stresses to be placed on the fastener’s structure. This can result in the weakening of the fastener or worse, catastrophic failure.
Minimum body length is a measurement from underneath the bearing surface of a bolt or screw’s head along its axis to the last scratch of thread. For rolled threads, it is the top of the extrusion angle.
Grip gaging length is a measurement from underneath the bearing surface of a bolt or screw’s head along its axis to the face of the proper GO thread ring gage (The proper ring gage is the gage that fits the correct diameter and thread pitch for a specific bolt or screw). When applied or tested, the ring gage should be screwed by hand on the bolt or screw as far as the thread will permit. Measure the distances between faces, the face of the screw & the face of the gage.
This is the maximum allowable length of the shank, the smooth portion of a bolt or screw’s shaft, for partially threaded bolts or screws.
Here is how to calculate Maximum Grip Gaging Length:
Calculations for LGmax:
Calculations for LB:
Get our Hex Head Cap Screws Minimum Body & Maximum Grip Gaging Length Printable table:
