On Sat, 06 Sep 2014 09:33:12 -0500, "Pete C."
wrote:


Mike Spencer wrote:

Flat head hex socket cap screws, 1/2" coarse thread, black finish.

What, if anything, should the marking on the head, "Y D" tell me about
the grade of the screw?

(Not old bolts; bought new circa 2004.)

Attaching a die insert to the upper die of a 300# air hammer.
Potentially dangerous should a bolt break during operation. Looking
for max strength fasteners. Wasn't so important for the purpose for
which I originally bought the screws.

Ying Dong noodle factory perhaps? If it's safety critical just go spend
the $20 and buy new grade 9 hardware from a reliable source.

It stands for Yahweh Destroys!
They're Karma Bolts.

--
Let no man imagine that he has no influence. Whoever he may be, and
wherever he may be placed, the man who thinks becomes a light and a power.
-- Henry George