Todd00

With all of this talk of the grade of bolts in a few threads lately, I was wondering if anyone had a nice little chart or something that they could post up of the SAE/metric grade levels, markings, etc. I've found that even the guys in the hardware store don't exactly know all there is to know about them, especially metric markings and such.

I did find a few pages like this with a google search:
http://www.volvospeed.com/Repair/boltgrade.htm

But was wondering if someone had an end-all chart of what was what. I know the basics, but more is always better.

DsITR

Todd, you mean something like this??

http://www.americanfastener.com/techref/grade.htm

It shows tensile strength, proof load, yield strength and the bolt head markings.

thawley

Carroll Smith's Nuts, Bolts and Fasteners and Plumbing Handbook
by Carroll Smith: http://www.amazon.com/exec/obi...books

Thawley

Crack Monkey

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DsR &raquo;</TD></TR><TR><TD CLASS="quote">It shows tensile strength, proof load, yield strength and the bolt head markings.</TD></TR></TABLE>

I'm not sure what those terms mean - is one of them the fasteners strength in shearing situations (like common harness installs)?

.RJ

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Crack Monkey &raquo;</TD></TR><TR><TD CLASS="quote">I'm not sure what those terms mean - is one of them the fasteners strength in shearing situations (like common harness installs)?</TD></TR></TABLE>

Crack Monkey

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .RJ &raquo;</TD></TR><TR><TD CLASS="quote">
&lt;image&gt;
</TD></TR></TABLE>

I don't think that answers the question. In many harness installs, there will be a certain amount of shearing force on the bolt (sideways - not pulling on the bolt lengthwise). What I have heard is the higher grade bolts have great "pulling lengthwise" strength, but lose "shearing stregth".

And, yes, those are all technical terms.

.RJ

You should be able to look up the tensile strength and the shear strength for each grade of bolt or material.

eHoward

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by thawley &raquo;</TD></TR><TR><TD CLASS="quote">Carroll Smith's Nuts, Bolts and Fasteners and Plumbing Handbook
by Carroll Smith: http://www.amazon.com/exec/obi...books

Thawley</TD></TR></TABLE>

Todd00

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Crack Monkey &raquo;</TD></TR><TR><TD CLASS="quote">

I don't think that answers the question. In many harness installs, there will be a certain amount of shearing force on the bolt (sideways - not pulling on the bolt lengthwise). What I have heard is the higher grade bolts have great "pulling lengthwise" strength, but lose "shearing stregth".

And, yes, those are all technical terms.</TD></TR></TABLE>

This is a decent webpage I found about Shear:

http://www.rockcrawler.com/tec...x.asp

Knestis

It's key that not all "Grade 8" bolts have the same properties. A really good bolt will ALWAYS bend before it breaks - the amount of "elongation" (how much it physically deforms) is pretty large, between its "yield strength" (where it permanently deforms) and its "fracture point" - where it blows out completely.

A military or aircraft (AN-spec) piece will always have this feature, because quality control is very high. A commercial Gr8 bolt might well perform less well in this regard and there are a TON of Home Depot "Grade 8" bits that may be as "strong" as the commercial stuff but are brittle as hell. OE automotive hardware is actually VERY good - particularly from Honda, VW, and other foreign makers.

Try this: Put a 1/4" test bolt in a vice and whack it sideways with a heavy hammer. If it just snaps off, you want a different source. It should bend so that you have some warning between the point that its limit has been exceeded (again, yield point) and when it decides to set free whatever it's retaining. It's not unusual for "Grade 5" bolts to behave better than "Grade 8" parts in this situation.

I don't believe that it is generally true that you have to sacrifice shear strength (the action of cutting something in half with scissors) to gain stength in tension (or tensile strength). It's actually pretty hard to put a bolt in either pure tension or shear loading situations - at least not where the load is considered to be "dynamic" or changing. These offset loads can be pesky to figure out but you can generally use a "double shear" mount if you plan ahead and do a little extra work. This sandwiches one piece (the belt tab, for example) between TWO plates rather than one - essentially doubling the cross-section of bolt being loaded while preventing twisting or bending offset loads.

It's also interesting at this point to consider "stretch" or "torque-to-yield" bolts, like some cars use for headbolts. These actually use that rounded piece of the curve in the diagram above, by getting tightened to the point where they permanently stretch but haven't yet reached the point where they bust...

K

HAEXF22B1

Wow. I know this is a really old post but it really helped me out and prevented me from making a thread about it. Thank you all for the information that was apparently available since I was 13 years old. This site really has great resources!