Ed Huntress writes:

On Sat, 6 Sep 2014 14:32:38 -0700 (PDT), "
wrote:

On Saturday, September 6, 2014 8:56:57 PM UTC, Mike Spencer wrote:

Well, bought from a dedicated industrial hardware distributor, not from
the local hardware store or Walmart.

I looked at MIL-HDBK-57F and did not find anything with YD. You
might try it using the computer to look for YD. I just looked at
manufacturers whose nome started with Y.

The term "CUST: YD" appears all over the place in MIL Specs. I have no
idea what it means, or if it's related to this. But I'll bet it does.
It appears in relation to MIL Spec screws, as well as many other
things.

You're right. The letter pair "YD" also appears alone in groups of
such pairs in mil spec docs, all entirely cryptic. Found lots of those
references but still nothing on YD as a meaningful mark. Maybe the
people that sold them to me will have time to tell me. They ship
fasteners by the pallette-load but will sell one bolt if you need it.
AFAICT their capscrews are listed as "steel" but I know they sell
specialty grades of this & that. I better try to ask.

Thanks,

- Mike

PS:

BTW, in a previous post, Pete C. wrote, "If it's safety critical just
go spend the $20 and buy new grade 9 hardware from a reliable source."
AFAIK, there is no "grade 9" spec. An Unbrako PDF on Igor Chudov's
website says that grade 8 is the highest strength level in the
relevant SAE spec and that socket head cap screws are made to a
different stadard anyhow. Are you BSing me Pete? Or just twitting me
because I' not a regular poster on
rec.crafts.politic^H^H^H^H^H^H^Hmetalworking?

--
Mike Spencer Nova Scotia, Canada