"Y D" marking on flat head cpa screw?

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.

TIA,

Reply to
Mike Spencer
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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.

Reply to
Pete C.

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

Reply to
Larry Jaques

Not the kind of technically informed answer I was looking for.

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

Good thought, though.

Reply to
Mike Spencer

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.

Dan

Reply to
dcaster

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.

Reply to
Ed Huntress

is it "Yet Defined" or "Yet Determined" or "Year Date" Hard to figure.

Martin

Reply to
Martin Eastburn

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?

Reply to
Mike Spencer

Grade 8 is what I meant to type, but I have indeed found references to a grade 9 out there. At any rate, "YD" is not one of the defined grade markings I'm aware of, the SAE stuff has the radial lines to indicate grade and metric has the x.x numbers for grade. Letter codes are common on cheap big box store grade 5 hardware and are used to indicate what the piece is, usually I see this as a three letter code.

Reply to
Pete C.

That reminds me of the special drawing...

(Damnit, can't find one online or on my hard drive. Anyway, every one of the measurements was "TBD".)

Reply to
Larry Jaques

"Larry Jaques"

'To Be Determined' ? heh heh .. ;>)}

Reply to
Phil Kangas

Rregarding "special" drawings, there was a legend at _American Machinist_ from the late '60s, in which they had a drawing from Japan of a new press one of their companies was building for sale in the US. There was an item on the drawing labelled "Water goat." No one could figure out what it was, until one of the editors slapped his head and said, "Of course! It's a hydraulic ram!"

True story.

Reply to
Ed Huntress

Ask at the place where you bought the screws in 2004.

I had a German mechanical shaper some years ago and got a service manual for it. IIRC, the term "shaper" translated to "chisel jack".

Pete Stanaitis

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Reply to
spaco

Along with that and in the same vain - I was in ATE - auto Test Systems testing semi parts...

One of my customers bought a machine from Japan. It had a Data General computer as a controller. The Japanese company ordered Japanese manuals for the computer, translated them into 'English' and shipped. (They could have ordered English manuals but .... ) Customer had heck understanding the basic commands and information.

But I like the Hydraulic Ram better!

Martin

Reply to
Martin Eastburn

Just for the record:

The vendor says the "Y D" markings on flat head, hex socket cap screws are maker's mark (maybe even, as suggested here, Ying Dong noodle factory :-) unrelated to the grade of the cap screws.

The grade is ASTM A574, comparable to (better than?) SAE grade 8.

For my purposes, flat head is preferable because I can pre-load the joint between two parts subject to impact, eliminating risk that the impact force would fall on the fasteners.

Tnx for the replies,

Reply to
Mike Spencer

We had a SATE at Cincinnati Electronics for the PRC-77 that was run by a Data General computer in the mid '70s. We had an engineer from Data General on site to maintain the computer, printers and equipment interfaces. He did a data dump and had paper hitting the ceiling. :(

Reply to
Michael A. Terrell

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