On Sun, 20 Jan 2008 11:15:18 +0100, Nick Mueller
wrote:

Ned Simmons wrote:

Certainly at that time friction
type connections were more common, but after looking around the web a
bit, I'm not sure that's true anymore.

There do exist bolts for both. Those for shearing do have a tighter
tolerance on their shaft and the two mating bores have to be drilled in
place while erecting the building (- architectural).

Here's a link (in German), but you also get the pictu
http://www.wuerth.de/de/service/dino/07schrauben-stahlbau.html

I get the pictures, but only a headache from the text g. Under AISC
code here in North America, holes for shear bearing bolts need not be
drilled in place. The AISC does require a reduction in shear capacity
if the bolt threads fall in the shear plane.


Interesting enough, shearing (called SL) is not allowed with dynamically
loaded constructions (cranes, bridges etc). They work with friction (called
HV) and have to be precisely torqued (including rules how to regularly
check the torque and the number of samples measured).

I think we're closer on this point, though the AISC seems to be looser
than your code in this regard as well. The rules for what sort of
joint is required for a particular loading condition are spelled out
in the AISC code I mentioned before.

--
Ned Simmons

On Sun, 20 Jan 2008 06:03:08 -0800, Larry Jaques
wrote:



Your post reminded me of Take 6, but here are all the fun eng. jokes:
Enjoy!


I think I've heard all the jokes before, but wouldn't have guessed
there were that many without seeing them all in one place.

--
Ned Simmons

On Sat, 19 Jan 2008 22:15:53 -0600, cavelamb himself
wrote:

http://www.boltcouncil.org/files/200...cification.pdf



I wonder if the whole argument is not explained on page 9 of that doc?

Hydrogen embattlement of hot dipped galvanized bolds???

The "brittle" hard bolt legend (not myth?)...

It does confirm what I read in the ASM handbook, and referred to in
the hydrogen embrittlement thread re plating causing more problems
than pickling. IIRC, the handbook said zinc plating was a particular
problem because the zinc seals the hydrogen in better than some other
metals.

--
Ned Simmons

cavelamb himself wrote:

Well, better anyway,
G

We can't judge this part right or wrong without putting numbers on it.

We made the most common error in discussion. We didn't specify what we were
exactly talking about. So everyone had his own picture in his head and
defended it. :-)

Furthermore, each field (be it planes or machines or whatever) has his
tradition in how to look at things and what they want to avoid or achieve
under all circumstances. The classical math to solve those problems always
needs some simplifications and so we should have agreed upon that in the
beginning.

Anyhow, interesting discussion with something to learn from!
Better than ... oh you know! ;-)

Nick
--
The lowcost-DRO:
http://www.yadro.de

Ned Simmons wrote:
On Sat, 19 Jan 2008 22:15:53 -0600, cavelamb himself
wrote:


http://www.boltcouncil.org/files/200...cification.pdf



I wonder if the whole argument is not explained on page 9 of that doc?

Hydrogen embattlement of hot dipped galvanized bolds???

The "brittle" hard bolt legend (not myth?)...


It does confirm what I read in the ASM handbook, and referred to in
the hydrogen embrittlement thread re plating causing more problems
than pickling. IIRC, the handbook said zinc plating was a particular
problem because the zinc seals the hydrogen in better than some other
metals.


A mate of mine said that Volvo have a policy of not allowing any bolts
on an engine over grade 10.9 due to concerns over possible hydrogen
embrittlement in the presence of moisture IIRC. The problem being an
issue with fasteners over 1100N/mm^2, 10.9 being 1000N/mm^2. I also was
told by my local fastener place that the supplier typically won't do
12.9 cap screws in plated anymore due to concerns over HE being a
possible issue even with baking after plating.

I'm a tech, not an engineer, so I bent a 1/4" Grade 8 bolt 90 degrees
to see if it would break. It didn't even crack. It bends like music
wire.

Jim Wilkins

Howard Eisenhauer wrote:
(...)
http://tantel.ca/Waste%20Oil%20Furnace.html

Great writeup, Howard!

Thanks and congratulations!

--Winston

"Ed Huntress" wrote:
You could try the SAE website, which has a bookstore and white papers in the
aerospace division.

I was mildly surprised to learn that the (automotive) SAE grade 2, 5,
8, etc bolt specifications do not include brittle fracture ratings.
This straight from the relevant spec committee chair people about 5 or
so years ago. I've never seen (or if I did I forgot :-() the actual
SAE bolt grade specs. I wonder if the metric bolt specs have brittle
fracture ratings. Aerospace fasteners better though or I'm sticking
to the bus. :-)

Jay

On Jan 21, 11:24 pm, Jim Wilkins wrote:
I'm a tech, not an engineer, so I bent a 1/4" Grade 8 bolt 90 degrees
to see if it would break. It didn't even crack. It bends like music
wire.

Jim Wilkins

It is nice that someone has actually done a test. Just don't be like
NASA and now believe that all grade 8 bolts can be bent.

Dan

On Jan 21, 10:27*pm, " wrote:
On Jan 21, 11:24 pm, Jim Wilkins wrote:

I'm a tech, not an engineer, so I bent a 1/4" Grade 8 bolt 90 degrees
to see if it would break. It didn't even crack. It bends like music
wire.

Jim Wilkins

It is nice that someone has actually done a test. *Just don't be like
NASA and now believe that all grade 8 bolts can be bent.

* * * * * * * * * * * * * * * * * * * * * * * * * *Dan

When I bent it further it snapped at the top end of the threads, with
only a little deformation there. The shank is now bent into a U with
0.18" between the legs and the outside of the bend still hasn't
cracked.

So for this particular Home Depot 'JH' bolt the rolled threads are
brittle but the shank isn't at all. I feel better about using Grade 8
bolts for machinery axles, not so good about hammering on such a
powerful & freedom-loving spring.

Jim Wilkins

Ned Simmons wrote:

snip

I'm an ME as well and haven't had any contact with actual structural
practice since I graduated in 1974. Certainly at that time friction
type connections were more common, but after looking around the web a
bit, I'm not sure that's true anymore. If I remember, I'll ask my
daughter to ask one of the structural engineers she deals with.

If you get the chance, I'd be interested to know what the structural
engineer says. Of course I guess it's possible that building codes
around the world may vary, but I get the impression that friction type
connections are the most common here in England.

Best wishes,

Chris

Ed Huntress wrote:
"Christopher Tidy" wrote in message
...

snip

In airframe construction, do the rivets carry a shear force in normal
operation, or only when the structure is overloaded?


I can't answer that with authority, but the literature on joint strength in
aircraft design and testing is loaded with references to rivet shear
strength. When they talk about bearing in this context it's almost always
about the bearing of the rivet on the hole. And the references to bearing of
the faying surfaces of skin are mostly about fretting and corrosion. Also,
thermal cycling is an issue with jet airliners, and maintaining sufficient
rivet clamping tension, just to prevent the rivets becoming loaded in
tension in service, is a big problem. Certainly a rivet loaded in tension by
displacement of the skins is not contributing to friction between the skins
by its clamping force.

So it looks to me like they are designed to be loaded in shear. Maybe you
can find an aircraft engineer who can confirm it. If I had to research it
for an article I'd be calling the engineers at the rivet manufacturers.

I'm going to see if I can buy a copy of that Astronautic Structures
Manual. Hopefully I can persuade an American seller to ship it to
England. Thankfully there's no import tax on books!

Best wishes,

Chris

Howard Eisenhauer wrote:
On Tue, 22 Jan 2008 01:15:05 GMT, Winston
wrote:


Howard Eisenhauer wrote:
(...)

http://tantel.ca/Waste%20Oil%20Furnace.html

Great writeup, Howard!

Thanks and congratulations!

--Winston


Thanks for the nice comment Winston, much appreaciated

H.

--Winston

On Tue, 22 Jan 2008 16:11:24 +0000, Christopher Tidy
wrote:

Ned Simmons wrote:

snip

I'm an ME as well and haven't had any contact with actual structural
practice since I graduated in 1974. Certainly at that time friction
type connections were more common, but after looking around the web a
bit, I'm not sure that's true anymore. If I remember, I'll ask my
daughter to ask one of the structural engineers she deals with.

If you get the chance, I'd be interested to know what the structural
engineer says. Of course I guess it's possible that building codes
around the world may vary, but I get the impression that friction type
connections are the most common here in England.


My daughter spoke with her engineer and he confirmed the impression I
got from my web browsing; that bearing type joints have become
prevalent in the US, at least in building construction.

--
Ned Simmons