When using a nut, lock washer and bolt, should you also use a flat
washer between the object and the lock washer? I have seen it done
a million times that way but it seems the flat washer defeats the
purpose of the lock washer. I assume the lock washer is there
to dig in a bit to the object and the nut to keep it from
loosening. The flat washer seems like it would allow the
lock washer to rotate without digging in to the object.
Anyone know?
Well, I'd say it depends...for instance, a soft washer with a large diameter
(fender washer) likely would provide more friction against the material
being bolted and so I have to at least
partially disagree with wiki on this..
It depends on the need.
If you are locking a nut to the base metal it is locking to -
use s star / split / double star / spring etc then the nut or a washer
and a nut. The washer spreads the presser across the nut and allows
it to rotate freely.
If you are trying to lock the nut and the thread then
you are trying to put side pressure on the nut....
Sometimes it is two nuts together with a washer.
Many uses.
Martin
>>> When using a nut, lock washer and bolt, should you also use a flat
>>> washer between the object and the lock washer? I have seen it done
>>> a million times that way but it seems the flat washer defeats the
>>> purpose of the lock washer. I assume the lock washer is there
>>> to dig in a bit to the object and the nut to keep it from
>>> loosening. The flat washer seems like it would allow the
>>> lock washer to rotate without digging in to the object.
>>>
>>> Anyone know?
>>>
>>
>>
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>
>
> Wikipedia ruins everything. I was expecting a big argument to start.
Despite what wiki says, I frequently use (and see used) a split lock
washer between a nut/bolt head and a flat washer. Even though it isn't
going to "bite" into the object being held or the nut/bolt head, it
still provides a longitudinal force to help keep it from becoming
unfastened.
Jon
It may be worth a more extensive search. A mechanical engineer I know,
whose a very sharp guy, told me that someone did a study and determined
that split washers work because they act as springs that keep the tension
on the threads in one direction.
Wikipedia is not always a reliable source.
There are numerous views regarding the in/effectiveness of split style
lockwashers.
One sure way to be certain is to use the proper Loctite or similar thread
locking product.
Another option is to use nylock or other types of self-locking nuts..
although this may be more costly than threadlocking products, and some types
are considered OTU one-time-use only.
Some simply consider split ring washers to be the work of the devil.
I found this looking for a more extensive set of videos of bolts loosening, and
the test rig used.
...
I didn't watch the rest; I notice they didn't say anything about the
torque applied on the test. Didn't appear to me it was more than just
"snugged down" rather than really torqued, but who's to know--they
cleverly didn't the applicator so can't even judge by looking the amount
of effort or size of ratchet, etc. While it may have been optical
delusion, looked to me like the bolt turned as well which wouldn't
indicate being very tight.
I don't have any scientific evidence but 50+ yr practical use on farm
indicates to me they serve a useful purpose.
I was impressed by this test at first, but then I realized looking at the
graph (
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) that the
major difference occurs only after the bolt is already too loose. The plots
diverge only after the bolt has already lost half its preload. They really
need to concentrate on the very first part of the curve where the bolt
starts to loosen. If you look closely, there is some indication one curve is
much steeper than the other at the start, but it is impossible to tell which
it is. Maybe they need to dial back the shaking a bit to be able to measure
that part of the curve better.
(following up to my own post)
What would be best would be to create a set of curves like this at several
vibration amplitudes and see if there is some level of vibration where the
lockwasher prevents any loosening, but the plain nut does not.
Would you be happy if I quoted Aristotle,
quoted the Bible, and then called you a bad
name? I'd sure not want you to leave the room
unsatisfied, and all.
.
Christopher A. Young
Learn more about Jesus
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hers
Wikipedia ruins everything. I was expecting a big argument to start.
I'm not a reliable enough source, either. I was advising the OP to look
around and make up his own mind, not to believe what I said without
question.
If I needed to know I'd do a literature search -- starting, I admit, by
looking up my old mechanical engineering colleague, to see if he could
remember where he saw the note (I think it was NASA tech briefs. NASA
was doing all sorts of studies in that vein for a while).
The Book of Gunner (in the Old Testament; one of the lost books)
relates:
4. And at the early moment of dawn, on the sixth day of the week. The
chariots were heard in the distance. My best look out came back into
camp, and reported that the enemy had amassed 500 chariots with warriors
and boys to assist.
5. My look outs from the high towers reported that behind the chariots
were amazing multitudes of busty and nubile women, both nobles and
wenches, and girls too young to have been married off to the warriors of
the opposing realm. And they had heard that I, Gunner, was legenday and
unstoppable in the bedroom, after having bilateral angio venoplasty paid
for by the tax payers of California, to treat my years of self inflicted
cigar smoking and drinking of whiskey.
6. I called heartily with booming and resonant voice (only coughing a
couple times account of the cigar) to my trumpeter, to rally my men, to
sound the charge. We had only 200 chariots with warriors, boys, and
small number of busty women, the remainder of the women were slumbering
in exhaustion after the bedroom epic drama of last night.
7. My chariots went into battle, and the fight was extreme. In the heat
of the battle, the opposing chariots wheels all came off, as if on
signal. Mine rallied and fought to the end, as I had used my lathe, and
hydraulic stamping press to generate suitably sized lock washers, to
hold the wheels on. (Can be seen, item #2814, on 55 tools blogspot,
hosted by Rob H.)
Aristotole say (or was it Confucious) man without lock washer have loose
nuts.
You misspelled your screen name, asshat.
.
Christopher A. Young
Learn more about Jesus
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.
That's the rcm way! I was hoping someone would do my
thread justice.
Which lubricant should be used on thread, when
tightning a bolt, nut, and lock washer? I'd think that
something with WD-40 would be used. Everyone
knows that WD-40 was designed as a lubricant.
Right, asshat?
.
Christopher A. Young
Learn more about Jesus
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.
That's the rcm way! I was hoping someone would do my
thread justice.
Most of the applications I have, I'd go with
farm experience rather than a web site that
claims this or that.
Do you ever stack a lock washer and flat
washer? And, how does that turn out?
.
Christopher A. Young
Learn more about Jesus
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.
I don't have any scientific evidence but 50+
yr practical use on farm indicates to me they
serve a useful purpose.
...
Quite a lot...a wide variety of applications have adjusting slots for
depth settings, etc., that have flat washers to span the slot and lock
washer on top. Works fine...
Again, for the application. I can imagine one can find vibration
regimes/applications where it doesn't suffice.
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