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Re: Grade 8 bolt properties

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I would guess that MSCR is short for "Machine SCRew", but it could be "machine screw BLANK BLANK".

You are correct regarding the grade 8 - med. carbon alloy, quenched and tempered. I would recommend keeping the SAE designation on the drawings, as it is a fairly recognized standard, and easy to identify when the builder goes to order them.


On Nov 23, 2009, at 10:22 AM, "Joseph R. Grill" <jrgrill(--nospam--at)> wrote:

I am working on a small project. Kind of a backwards design for some small steel brackets that are in the process of being detailed. The drawings the steel detailer call for Grade 8 1/4x20 bolts. I have found some information on the internet. What I think should be called out should be ASTM A354 Grade BD (it appears that it is in the same category as SAE J429 Grade 8). It has a yield strength of 130 ksi and a tensile strength of 150 ksi. Am I correct?

In addition, the shop drawings that are in production, call for a ¼”-20 FH MSCR in another application on the project. I can see that it will be a ¼” flat head screw (the drawings show a countersunk part for the application and I believe the receiving par t will be drilled and tapped. But what does the “MSCR” stand for? Sorry for the confusion here. And, what would the correct AST M designation be? Same as above for the bolts as the table I found from American Fastener shows ASTM A#%$ Grade BD being for Bolts, Scr ews, and Studs.

Thanks for the help

Joe Grill

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