I noticed that the hex head lag screw I have is marked with '4.8' on the head, but when I measured the shank with Vernier calipers, it came out to 1/4 inch. I'm curious about the significance of these markings. Do they indicate something specific, or are they just there to confuse people? I know that 4.8 mm is the size of a #10 screw, but I'm looking for clarity here.
2 Answers
The '4.8' marking actually refers to the tensile strength of the bolt, not its size. So, it’s more about how strong it is rather than how big it is.
That '4.8' is the metric grade for the bolt, nothing to do with its size. It's likely a 6mm lag bolt, as 1/4 inch is about 6.4 mm.
Thanks for clarifying that! I just hope it's not rated at 4.8 Nm...