Hairline Crack in a hex driver.

[NKlamerus]

I've broken my fair share of Allen drivers over the years, mostly metric as I'm a sewing and embroidery machine technician.

A visiting tech brought this in today and I noticed it was gaining and losing iron decor twists as he used it, took a closer look and found this hairline crack down the center of the twists, first time I've seen anything other than a bend or shear across the hex.

I'm 100% PB Swiss Grip Allen drivers, most the traditional t handle drivers are too heavy on the end and they don't fit into tight spaces in embroidery machines.

 

[Bubba Fett]

Looks like the metal wasn't heat treated properly. See if you can warranty it.

 

[NKlamerus]

He probably will, said it was from harbor freight but I'm not sure

 

[Tools4Me]

Next time you are using the tool and unwinding the twist, try pushing down hard on the top of the t-handle at the same time. See if you can turn the split section into one of these.

 

[neophyte]

Looks like the metal wasn't heat treated properly. See if you can warranty it.

I disagree.

The grain structure in the steel of a rod or a hex wrench is going to be parallel with the rod.
Cold rolling or drawing the metal would make the grain size of the steel smaller,
thus increasing strength,
But at a certain point the steel molecular structure might fracture instead of decreasing grain size.
Alternatively, there might have been a flaw or inconsistency in the steel, that then got drawn out along the steel grain structure as the steel was rolled out into bar shape, then formed into the dimensional hex shape.
If the wrench has a warrantee, it should be replaced because this was definitely a defect in material or workmanship.
I just don’t think it was a heat treating defect.

 

[Bubba Fett]

I disagree.

The grain structure in the steel of a rod or a hex wrench is going to be parallel with the rod.
Cold rolling or drawing the metal would make the grain size of the steel smaller,
thus increasing strength,
But at a certain point the steel molecular structure might fracture instead of decreasing grain size.
Alternatively, there might have been a flaw or inconsistency in the steel, that then got drawn out along the steel grain structure as the steel was rolled out into bar shape, then formed into the dimensional hex shape.
If the wrench has a warrantee, it should be replaced because this was definitely a defect in material or workmanship.
I just don’t think it was a heat treating defect.

Well it is from HF, so defective metals don't surprise me.