Speaking of home wood-related repairs...

[Lew Hodgett]

Ok - I'll chime in . . Structural Engineer, with degrees and official License who has designed many buildings.

the 90# for a 16d box nail is about right on . . to start with. There's a lot of factors that could increase or decrease that number by a factor of two or so depending on exactly what's going on and what kind of loads you are holding up (for example:short duration loads like wind, multiply by 1.6; hot, wet conditions might be multiplied by about 0.6 or so)

Steel strength for get's pretty meaningless since it's wood that always fails in a proper joint, but the minimum steel yield strength for both nails and wood screw is 70,000 psi to 100,000 psi. Neither nails or screws are usually heat treated.

Normal screews are usually not hardened; however, this thread started somewhere way back when talkung about dry wall screws which are a different ball game.

SFWIW, also have the shingle issued by the state hanging on the wall.

Lew

[fftt]

Are you asking about the nail ...all by itself, no timber? Mounted in steel test machine by some sort of fixturing?

A 16d nail has about .02 sq in cross section (as per another poster's calc) ....so pick your nail material ultimate shear stress & mutlitply by .02

But the shear strength of a 16d nail isolated by itself in a test machine is pretty meaningless since a 16d nail will never be used in that fashion unless you plan to use it as a shear pin in a lawn mower.

cheers Bob

cheers Bob

[-MIKE-]

Yes, the test situation, mounted in a testing machine. There are a lot of testing situations that never happen in the real world, but they still do the tests. :-)

[fftt]

ld, but they still do the tests. :-)

[J. Clarke]

If you're testing shear strength then you need to make up a fixture that fits the nail, with a nail-sized hole in it. Seems like a strange thing to do when a nail would not normally be used that way. Do you recall the circumstances under which the test was conducted?

[DanG]

Why not take two steel blocks of the same size. Drill a clearance hole through each, offset about a 1/4". Place a nail through the holes. Place both blocks in a vise and close until the nail shears. Once you are sure of the set up, it should be fairly easy to devise a means of measuring the force. I've not ever had a need for the data short of meeting a particular structural rating that an engineer designed and specified.

I do wish I had kept the drawing of that project. It required nailing a series of 2x6 blocks onto existing 2x10 joists with a set number of 10d common nails. The block was to be 1 foot long as I recall with over 40 nails in it. I asked how he came up with the numbers, etc; and expressed my concern that the board(s) would shatter or split from the sheer number of shear nails. He was worried about the forces (known and unknown) that he wanted to overcome and not necessarily the limits of the material. We arrived at a reasonable compromise that satisfied each of us. It seems to me the compromise involved a longer 2x6, use of 16d, and some predrilling. I don't believe the number of fasteners changed much. I had offered using steel, bolts, etc. I think the main reason not to change had to do with not wanting to redraw/recalculate.

[-MIKE-]

but they still do the tests. :-)

Get over yourself, Bob. So every stress test done in the lab is a replication of a real life application, huh?

[-MIKE-]

I'm not trying to justify my number, despite what douche bag Bob says to try to make himself feel superior in some way.

I honestly want to know what the real number is. Since we had some engineers come in here, saying they've conducted those types of tests, I've been trying to ask them.

Have you honestly never seen those tests they do at labs (Underwriters' Labs might be one example) where they take a material way beyond its limits to see when it crack, shears, pulls apart, shatters, or whatever?

Apparently, Bob thinks I'm full of it for suggesting this happens.

[J. Clarke]

They don't "take it way beyond its limits", they determine what its limits are.

And I've not just seen such tests, I've planned and monitored them and analyzed the results. Never had occasion to do one on a nail in a fixture intended to determine its shear strength though. I'ts not something that I can imagine anybody wanting to do unless they were perhaps quality control people in a nail factory or lawyers trying to prove that a batch of nails was defective. In most engineering you don't care how strong the _fastener_ is, you care how strong the _joint_ is and to test that you make up sample joints and test them.

No, for arguing about things like the definition of "shear".

[-MIKE-]

Wow. More semantics policing. You couldn't take for granted that we were talking about the same thing?

I'll quote...

me:

him: > Back to your old behavior, I see .....writing nonsense & digging > holes.

[RicodJour]

Oh, you mean like... Bob?

Sheesh. Will you give it the f*ck up already? Don't you understand? Bob IS one of the guys that did such testing for years. I first ran into him probably close to ten years ago on alt.building.construction. He knows his shit, and was pointing out that you were mistaken about that number, as did many other people.

You're just getting twisted up over something YOU don't understand. If you want an education, go get it - it's not someone else's job to give it to you. DAGS "nail shear strength testing". BTW, do not be mislead by that idiot's video on YouTube and Metacafe that shows him swatting nails and screws and calling that a shear strength test. Swatting them with a hammer is not a shear test (though it can be indicative of the shear strength).

R

[-MIKE-]

I did ask him, and he went off on me out digging the hole further. There's a pile-on mentality in here that cracks me up.

[RicodJour]

Perhaps you were looking for a Stuart Smalley newsgroup...? I'll see if I can help. You're good enough, you're smart enough, and doggone it, people like you!

You were still wrong about the 16000 lbs. ;)

R

[-MIKE-]

Great, I'm over that. I've been over that. I'm not the one who keeps bringing it up.

What I'm interested in are the real numbers. I thought others might be, too, but all you seem to be interested in is pointing out what an idiot you think I am, which says much more about you than me.

I saw that Bob was an expert and asked about three times and got nothing more than finger pointing.

I asked that other guy, Richk Structural Engineer, to explain his numbers a little more. Haven't heard from him, but maybe he'll add something after he reads it.

[Tom Watson]

On Sun, 11 Oct 2009 13:22:47 -0500, -MIKE- wrote: self justifying silliness.

OK, you win this weeks Robatoy Memorial I Won't Admit I'm Wrong Award.

A bronzed jointer guard will be presented to you at the next meeting.

Thank you for playing.

Regards,

Tom Watson

[J. Clarke]

Nope, one thing I learned in many years of engineering is that when someone is throwing around words as loosely as you do, its best to press for all the precision that one can get out of them, otherwise they get very upset when what was delivered was not what they wanted.

The sad thing is that you don't even try to recognize the hole you're digging.

[fftt]

world, but they still do the tests. :-) =A0 Back to your old behavior, I see .....writing nonsense & digging

Mike-

You continue to post unsubstantiated BS. back pedaling & back filling as you go, changing the subject and obfuscating

[fftt]

I'm far from superior....... I come to this newsgroup to learn stuff (as I assume most others do)

when people (like you) post unsupported & unsupportable claims it reduces the value of this forum

you asked for info, people provide it (you disbelieved it) ....you were asked for cites or examples & you provided none...just more hand waving

[fftt]

Mike-

I sorry you're pissed off. Lots of guys provided good comments & good information

One of my later posts gave you range of answers

reposted here:

depends on the loading conditions & assembly

an ultimate number or an allowable (like a working load) number?

allowable in timber like ~100lbs

ultimate load in timber, probably 400lbs

ultimate load in a test machine...depending on the steel condition / alloy; maybe 800+ lbs

[-MIKE-]

When you entered the discussion, you made it apparent that you were an expert who had done testing like that, and that I was way off.

I wrote, "Cool. Any idea what it can take?" That's me moving on.

You gave me numbers. I didn't "disbelieve" anything. I tried to clarify what the tests were and wanted to start a discussion about lab tests that are done to test materials until they break, not until they lose their grip in wood.

I suggesting that tests are done on materials that go way beyond what those materials will ever handle in real life application and you called that "nonsense."

It's clear to me that you're only interested in telling me how wrong I am.