Steel grades for bolts?

"Konstantin Shemyak" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I snapped a head off an allen bolt -- much easier than
I'd expect. It was fixing a rack; and I don't want my
stem bolts to be that weak! How to get any idea about
their quality to buy the correct ones?

Some bolts from my toolbox have marks on their heads,
like: "SBE 8.8", "FS A2-70". Does it indicate steel grade?
Web search on these abbreviations did not return anything.
Generally, any pointers to the "bolt science" are
appreciated.

http://www.sizes.com/tools/bolts_SAEtork.htm

Avoid "Grade 8" bolts. If you need a graded bolt use aircraft certified bolts
generally available surplus from many sources. But they aren't metric. If you
want the best Allen bolts buy them from the Allen folks.After all, they
invented them.
It's hard to believe that you cound apply enough torque to a rack bolt-usually
a 5mm-to snap the head off without stripping the fitting you were screwing it
into.
Phil Brown

On Sat, 26 Jun 2004 18:07:35 GMT, Konstantin Shemyak <[email hidden]>

Quoted message said:

I snapped a head off an allen bolt -- much easier than
I'd expect. It was fixing a rack; and I don't want my
stem bolts to be that weak! How to get any idea about
their quality to buy the correct ones?

Some bolts from my toolbox have marks on their heads,
like: "SBE 8.8", "FS A2-70". Does it indicate steel grade?
Web search on these abbreviations did not return anything.
Generally, any pointers to the "bolt science" are
appreciated.

Metric bolts marked 8.8 which actually meet that spec are roughly the
equivalent of an SAE Grade 5, which is good but fairly ordinary.
Unfortunately, such markings are not reliable; there is a lot of
hardware on the market which bears fraudulent grade markings, both in
metric and SAE sizes. A metric fastener from a known reliable source
which bears a 10.9 marking should be good stuff; if it's up to spec
for that marking, it will be capable of developing tensions that would
typically shear threads from a tapped hole in an aluminum part before
the bolt would break.

As for the "FS A2-70" markings, those are not from a system with which
I'm familiar.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Surrealism is a pectinated ranzel.

Konstantin Shemyak said:

like: "SBE 8.8", "FS A2-70". Does it indicate steel grade?

No URLs at hand, unfortunately. 8.8 rates the mechanical strength and is
for fairly standard bolts etc. 10.9 and 12.2 are the better ratings. A2
indicates a rust-free bolt. I am not sure whether higher grades (A4) are
for higher strength or better resistance to corrosion - the latter, I
suppose.

Patrick

That's 10.9 and 12.9 ... typical grade markings for metric bolts. First
number is nominal ultimate tensile strength and second is % UTS that yield
occurs IIRC.

5.8 is roughtly equiv of SAE grade 2, 8.8 is roughly equiv of SAE grade 5
and 10.9 roughly equiv of SAE grade 8 IIRC

The higher grades are stronger, and will require higher tigtening torques
upon installation. For better corrosion resistance look at stainless steel,
(A2 is equiv of 304 stainless, A4 is equiv of 316 stainless) but the
stainless will be much lower strength (maybe like a 5.8 or 8.8?)

You might call Metric Screw and Tool, Wakefield, MA
http://www.metricscrew-toolco.com/ (or Maryland Metric
http://mdmetric.com/ )
for more info and catalog.

"Patrick Hansmeier" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Konstantin Shemyak said:

like: "SBE 8.8", "FS A2-70". Does it indicate steel grade?

No URLs at hand, unfortunately. 8.8 rates the mechanical strength and is
for fairly standard bolts etc. 10.9 and 12.2 are the better ratings. A2
indicates a rust-free bolt. I am not sure whether higher grades (A4) are
for higher strength or better resistance to corrosion - the latter, I
suppose.

Patrick

The Masked Marv said:

That's 10.9 and 12.9 ... typical grade markings for metric bolts. First
number is nominal ultimate tensile strength and second is % UTS that
yield occurs IIRC.
5.8 is roughtly equiv of SAE grade 2, 8.8 is roughly equiv of SAE grade
5 and 10.9 roughly equiv of SAE grade 8 IIRC
The higher grades are stronger, and will require higher tigtening
torques upon installation. For better corrosion resistance look at
stainless steel, (A2 is equiv of 304 stainless, A4 is equiv of 316
stainless) but the stainless will be much lower strength (maybe like a
5.8 or 8.8?)
You might call Metric Screw and Tool, Wakefield, MA http://www.metricscrew-/http://www.metricscrew-
toolco.com/ (or Maryland Metric http://mdmetric.com/http://mdmetric.com/
) for more info and catalog.
"Patrick Hansmeier" <[email hidden]> wrote in message news:[email hidden]:[email hidden]-
Dortmund.DE...

Quoted message said:

Konstantin Shemyak said:

like: "SBE 8.8", "FS A2-70". Does it indicate steel grade?

No URLs at hand, unfortunately. 8.8 rates the mechanical strength and
is for fairly standard bolts etc. 10.9 and
12.2 are the better ratings. A2 indicates a rust-free bolt. I am not
sure whether higher grades (A4) are for higher strength or better
resistance to corrosion - the latter, I suppose.

Patrick

Good references " Masked Marv" The Metric Screw and Tool Company has
very good information on metric screws,,,... but it isn't the world's
most friendly site. The DIN 931 Cap Screws with partial thread might
work well for rack mounting, if the unthreaded section is the same
length as the thickness of the rack member. Maryland Metric's site has a
very large amount of references and is a little easier to navigate with
high speed connection and Adobe Accrobat Reader.

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