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bolt tightening

bolt tightening

bolt tightening

(OP)
How is it called the tightening procedure made by man without any control wrench but at the max possibility of the man ?? I know there is a definition but i don't remember it.
Thanks

RE: bolt tightening

For a vertical bolt it is probably the weight of the man...

But that's the extreme end.

Valves use a force of 50N at the handwheel if that's any use.

But a tightening procedure without using a torque wrench is worthless due to the huge variance in applicable load.

And that's before someone extends the wrench using a scaffold pole....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: bolt tightening

You might be thinking of "snug tight".

But that is not the full effort of a (manly) man.

RE: bolt tightening

(OP)
MintJulep : that is what I was looking for. Thks

RE: bolt tightening

Is that the same as what I'd call "Hand-tight"?

RE: bolt tightening

hokie,

I can agree with you to a certain extent about the turn of the nut method, but what was in my mind being talked about was as the OP says "at the max possibility of the man ??" No mention of turn only a set amount there.

THAT to me is what was worthless as there are simply too many variables.

The bolt tightening method is still rather vague as you need to remember hw far you have moved the bolt and whether the person is actually able to move it that far. Or thinks that it was too easy and goes an extra 1/2 a turn....

"Snug tight is also rather vague and whilst it looks fine for a single bolt, what happens in a multi bolt scenario where if you tighten on bolt the other become loose. Do you tighten them again to be "snug"?

And all because someone can't be bothered to buy a torque wrench?? The link talks about "expensive" torque wrenches. Give me a break.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: bolt tightening

A BPS for Hokey... an excellent Portland Bolt article. Because of irregular coef of friction, using torque values may give differning results. Turn of Nut is almost universally commonplace. Not much to go wrong. The clamping force although not exact, is reasonably uniform using this method.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: bolt tightening

robyengIT,

What if it is a woman tightening it? According to MIL-STD-1472H, Table XLIX, a fifth percentile woman can exert 103N (23lb) force in a standing one handed pull. A 95th percentile male can do 628N (141lb).

I have worked out turn of the nut for electronics assembly, and I have found it to not be feasible. The rotation from "snug" to tight is just a few degrees, not nearly enough to account for differing interpretations of "snug". This does not rule out the method for architectural or heavy duty industrial applications with longer bolts.

--
JHG

RE: bolt tightening

Looking back at the original question (uncontrolled, at the maximum strength of the man), that's what we call "murdering it up" or "graunching it up" or "TAF"

RE: bolt tightening

A while ago I heard about ultrasonic bolt elongation testing. Since no one has mentioned it, can I assume it's not in common use yet?

My glass has a v/c ratio of 0.5

Maybe the tyranny of Murphy is the penalty for hubris. - http://xkcd.com/319/

RE: bolt tightening

For god's sakes - we're all supposed to be engineers who use numbers and measurable things.

"Snug fit" " Hand tight", and in that turn of a nut description "the assembly has been tightened sufficiently so that the nut cannot be removed without the use of a wrench" are all incredibly vague and subject to interpretation and individual strength or even just how much access there is to the nut in question / both ends of bolt or other end of the stud. Not to mention the size of the "wrench".

Torque might not be perfect as it also has variance, but my god it's so much better than these vague phrases that none of us can agree on!

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: bolt tightening

Gutentight.

RE: bolt tightening

With the variability in friction surfaces, I don't think torque is all that it's cracked up to be... most steel code agencies recommend against it. Twist off or indicating washers seems to be the most precise.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: bolt tightening

The main crank (harmonic balancer) bolt on my motor is either one that is tightened to a specified torque, then advanced another 140 degrees, or the other bolt is simply tightened to 240 ft-lbs of torque. The first bolt actually stretches during the tightening and is not supposed to be re-used after removal. The 2 bolts are made of different metals.

RE: bolt tightening

Finger tight
Hand tight
Really tight
Extra tight
Flogged tight
Oop's

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

RE: bolt tightening

The following may be of interest regarding some of the general discussions in this thread:

Edit: The attached illustrates the second paragraph of text.
In summary: A fully tensioned fastener is insensitive to snug tight tension, as the fastener is plastically deformed.

Regards.

For bolts equal to or greater than about ¾ in. dia., snug position provided by an
impact wrench is approximately equal to the tightness attained by the full effort of a
man using an ordinary spud wrench.

Controlling tension by the turn-of-nut method is primarily a strain control. If
the elongation of the bolt remains within the elastic range, both the starting point
(i.e., snug tight) and the amount and accuracy of the nut rotation beyond snug tight
will be influential in determining the preload. However, in the inelastic region the
load versus elongation curve is relatively flat, with the consequence that variations
in the snug-tight condition result in only minor variations in the preload of the
installed bolt.

Ex:

https://www.boltcouncil.org/files/2ndEditionGuide....

RE: bolt tightening

Hand tightened or Hand Torqued is what we call this. Though, I prefer "hand tightened" because when I hear torque my mind automatically sees a wrench.

RE: bolt tightening

Quote (CraneNINJA)


...I prefer "hand tightened" because when I hear torque my mind automatically sees a wrench.

Also, the problem with torque implies not only a 'wrench' but also a 'number', which is sort of oxymoronic when the word 'hand' is used as that implies that it's not exact.

John R. Baker, P.E. (ret)
Irvine, CA
Siemens PLM:
UG/NX Museum:

The secret of life is not finding someone to live with
It's finding someone you can't live without

RE: bolt tightening

A torque wrench gives reliable results when used for tightening, i.e. when the bolt or head moves. If used for checking bolts which don't move, it shows nothing. So if a torque wrench is used, the bolt should be marked first to assure movement.

RE: bolt tightening

For shade tree mechanics I've always used the rule "Tighten until it gets loose then back off a quarter turn".

----------------------------------------

The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.

RE: bolt tightening

I've heard, "tighten till it cracks, then back off half a turn..." similar...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: bolt tightening

Hokie.

If it doesn't move it tells you someone has already gone a bit too far....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: bolt tightening

LI,

We’ll have to agree to disagree. A nut can lock up before it is tight for a number of reasons, but if you stop while tightening, it can be difficult to get it moving again.

RE: bolt tightening

Mmanual tightening of screws causes calluses.

luis

RE: bolt tightening

".....The tightening procedure performed by man without any control....." is INCORRECT PROCEDURE.
The best procedure is "Measuring bolt elongation".
All depends the context.
I worked with 76 studs M220 x 2500 mm (850 kg) for Nuclear Reactor Pressure Vessel. Hydraulic bolt tensioner is used for tensioning all studs at the same time.

Regards

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