Hi,

Say I do a nut or bolt up to (for example) 120ft/lbs as checked by a
decent torque wrench in calibration, can that same nut/bolt be undone by
the same amount of force, or does it take more - and if so, how much more
and why?

On 06/02/2018 21:42, Chris wrote:

Hi,

Say I do a nut or bolt up to (for example) 120ft/lbs as checked by a
decent torque wrench in calibration, can that same nut/bolt be undone by
the same amount of force, or does it take more - and if so, how much more
and why?

I would guess more, because when doing it up it must be sliding, but
when undoing you have to overcome the coefficient of static friction,
which is always more than the coefficient of dynamic friction.
--
Dave W

On 06/02/2018 21:42, Chris wrote:

Hi,

Say I do a nut or bolt up to (for example) 120ft/lbs as checked by a
decent torque wrench in calibration, can that same nut/bolt be undone by
the same amount of force, or does it take more - and if so, how much more
and why?


More.

Why? As you tighten, the thread heats and expands. When it cools, it
'nips up' as the metal contracts. When you try to undo, the extra force
is needed to compensate for this 'nipping up'.

How much? I recall having to do a calculation at Uni, in the first year
some of the courses were common to the Mechanicals. I seem to recall
there was a set of formulae to work out the forces on a thread but that
was 40+ years ago.

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On 06/02/18 21:58, Dave W wrote:
On 06/02/2018 21:42, Chris wrote:

Hi,

Say I do a nut or bolt up to (for example) 120ft/lbs as checked by a
decent torque wrench in calibration, can that same nut/bolt be undone by
the same amount of force, or does it take more - and if so, how much more
and why?

I would guess more, because when doing it up it must be sliding, but
when undoing you have to overcome the coefficient of static friction,
which is always more than the coefficient of dynamic friction.

I'd agree with that - but the heating effect mentioned in the previous
post is interesting.

I'll add another - corrosion. Even the slightest superficial surface
corrosion on the threads or under the head is likely to add something to
the break force required to get it undoing.

Dave W wrote:

On 06/02/2018 21:42, Chris wrote:

Hi,

Say I do a nut or bolt up to (for example) 120ft/lbs as checked by a
decent torque wrench in calibration, can that same nut/bolt be undone by
the same amount of force, or does it take more - and if so, how much more
and why?

I would guess more, because when doing it up it must be sliding, but
when undoing you have to overcome the coefficient of static friction,
which is always more than the coefficient of dynamic friction.

An exception, in the case of some cylinder head bolts, is the use of
bolts torqued beyond their elasic limit.
--

Roger Hayter

On 07/02/2018 00:22, Roger Hayter wrote:
Dave W wrote:

On 06/02/2018 21:42, Chris wrote:

Hi,

Say I do a nut or bolt up to (for example) 120ft/lbs as checked by a
decent torque wrench in calibration, can that same nut/bolt be undone by
the same amount of force, or does it take more - and if so, how much more
and why?

I would guess more, because when doing it up it must be sliding, but
when undoing you have to overcome the coefficient of static friction,
which is always more than the coefficient of dynamic friction.

An exception, in the case of some cylinder head bolts, is the use of
bolts torqued beyond their elasic limit.


The idea of those bolts is simply to ensure a more predictable clamping
force than can be obtained by measuring the torque applied. A torque
wrench doesn't measure the clamping force, at least not directly. Other
factors, dirt etc, can cause higher/lower torques to be applied by the
wrench to achieve the same clamping force.

The bolts, at least when new, are designed to 'go over' they limit
reliably. At that point the clamping force should be as expected.

That isn't ex Uni, it was explained to me by a tank mechanic. (Not the
water kind.) He was working on an M1A1 engine.



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On Tue, 06 Feb 2018 22:48:45 +0000, Tim Watts wrote:

I'll add another - corrosion. Even the slightest superficial surface
corrosion on the threads or under the head is likely to add something to
the break force required to get it undoing.

Corrosion throws a complete unknown into the mix so there's no point
speculating. ISTR from somewhere (I could be wildly out here, though)
that even under optimal conditions (clean, lubricated threads on both
components) the force needed to release a fastener can be 2 to 3 times as
much as was used to tighten it in the first place. That sounds like a
huge discrepancy and I may be wrong. But I might be right. :-/




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Brian Reay wrote:

On 07/02/2018 00:22, Roger Hayter wrote:
Dave W wrote:

On 06/02/2018 21:42, Chris wrote:

Hi,

Say I do a nut or bolt up to (for example) 120ft/lbs as checked by a
decent torque wrench in calibration, can that same nut/bolt be undone by
the same amount of force, or does it take more - and if so, how much more
and why?

I would guess more, because when doing it up it must be sliding, but
when undoing you have to overcome the coefficient of static friction,
which is always more than the coefficient of dynamic friction.

An exception, in the case of some cylinder head bolts, is the use of
bolts torqued beyond their elasic limit.


The idea of those bolts is simply to ensure a more predictable clamping
force than can be obtained by measuring the torque applied. A torque
wrench doesn't measure the clamping force, at least not directly. Other
factors, dirt etc, can cause higher/lower torques to be applied by the
wrench to achieve the same clamping force.

The bolts, at least when new, are designed to 'go over' they limit
reliably. At that point the clamping force should be as expected.

That isn't ex Uni, it was explained to me by a tank mechanic. (Not the
water kind.) He was working on an M1A1 engine.

They're still very probably going to need less torque to undo than they
did to do up.

--

Roger Hayter

On 06/02/2018 21:42, Chris wrote:

Hi,

Say I do a nut or bolt up to (for example) 120ft/lbs as checked by a
decent torque wrench in calibration, can that same nut/bolt be undone by
the same amount of force, or does it take more - and if so, how much more
and why?

Assuming everything including friction etc is constant, then less as
you'll have the thread angle coupled with tension to assist in the undoing.

If there is any form of stiction, cold welding etc, then who knows.

Otherwise bolts would never be able to rattle loose or require crinkle
and/or split washers to prevent a bolt or nut from unwinding.

On 07/02/2018 01:27, Cursitor Doom wrote:
On Tue, 06 Feb 2018 22:48:45 +0000, Tim Watts wrote:

I'll add another - corrosion. Even the slightest superficial surface
corrosion on the threads or under the head is likely to add something to
the break force required to get it undoing.

Corrosion throws a complete unknown into the mix so there's no point
speculating.

I'd be inclined to speculate away, having eventually undone a steel
pedal spindle from an alloy bicycle crank.

--
Cheers, Rob

On 06/02/18 21:42, Chris wrote:

Hi,

Say I do a nut or bolt up to (for example) 120ft/lbs as checked by a
decent torque wrench in calibration, can that same nut/bolt be undone by
the same amount of force, or does it take more - and if so, how much more
and why?

Depends how rusty its got in the meantime

And how much plastic deformation and creep has happened.


--
€œA leader is best When people barely know he exists. Of a good leader,
who talks little,When his work is done, his aim fulfilled,They will say,
€œWe did this ourselves.€�

ۥ Lao Tzu, Tao Te Ching

I'd imagine it depends on the materials involved and the amount it bites
into the substance you are bolting together and the amount of stretch as its
done up. Remember watching the crews changing out items on both Hubble and
the iss having to up the torque to get some bolts out.
Brian

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"Chris" wrote in message
news

Hi,

Say I do a nut or bolt up to (for example) 120ft/lbs as checked by a
decent torque wrench in calibration, can that same nut/bolt be undone by
the same amount of force, or does it take more - and if so, how much more
and why?

On 07/02/2018 07:28, Brian Gaff wrote:

I'd imagine it depends on the materials involved and the amount it bites
into the substance you are bolting together and the amount of stretch as its
done up. Remember watching the crews changing out items on both Hubble and
the iss having to up the torque to get some bolts out.

It is particularly difficult in the vacuum of space as metallic surfaces
can slowly cold weld together by diffusion. That tends not to happen on
Earth unless you are working on parts inside high vacuum systems.

My instinct is that AOBE tightening you are working against dynamic
friction until the torque wrench limits. Undoing you are working against
static friction which is always higher until the thing starts to move.

In reality corrosion tends to stick steel nuts and bolts together on
Earth which can make penetrating oil essential to get them apart.

--
Regards,
Martin Brown

In article ,
Brian Reay wrote:
An exception, in the case of some cylinder head bolts, is the use of
bolts torqued beyond their elasic limit.


The idea of those bolts is simply to ensure a more predictable clamping
force than can be obtained by measuring the torque applied. A torque
wrench doesn't measure the clamping force, at least not directly. Other
factors, dirt etc, can cause higher/lower torques to be applied by the
wrench to achieve the same clamping force.

But with stretch bolts, you start out with a given torque setting, then
turn them to a specific angle (number of degrees) after that.

So if the threads were tight etc in any way, that initial torque setting
would still be wrong.

You should always clean any thread on a fixing where the torque is
critical.

The big problem is torque wrenches are often well out of calibration. And
require skill to use. Watching a tyre place the other day, the fitter
pushed on the torque wrench long after it had clicked. Giving it a good
jerk after it had.

So it might be in practice that stretch bolts are more likely to be set
nearly ideal. But I dunno for sure.

I do know that gorilla mechanics will break anything, though.

--
*If a turtle doesn't have a shell, is he homeless or naked?

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Cursitor Doom wrote:
On Tue, 06 Feb 2018 22:48:45 +0000, Tim Watts wrote:

I'll add another - corrosion. Even the slightest superficial surface
corrosion on the threads or under the head is likely to add something to
the break force required to get it undoing.

Corrosion throws a complete unknown into the mix so there's no point
speculating. ISTR from somewhere (I could be wildly out here, though)
that even under optimal conditions (clean, lubricated threads on both
components) the force needed to release a fastener can be 2 to 3 times
as much as was used to tighten it in the first place. That sounds like
a huge discrepancy and I may be wrong. But I might be right. :-/

I always use a thread sealer on all the bolts which go into ally.
Otherwise they are likely to corrode over the years. That thread sealer
also locks, so requires a lot more torque to undo - and does so with a
'snap'

--
*Shin: a device for finding furniture in the dark *

Dave Plowman London SW
To e-mail, change noise into sound.

On 07/02/2018 02:12, Roger Hayter wrote:
Brian Reay wrote:

On 07/02/2018 00:22, Roger Hayter wrote:
Dave W wrote:

On 06/02/2018 21:42, Chris wrote:

Hi,

Say I do a nut or bolt up to (for example) 120ft/lbs as checked by a
decent torque wrench in calibration, can that same nut/bolt be undone by
the same amount of force, or does it take more - and if so, how much more
and why?

I would guess more, because when doing it up it must be sliding, but
when undoing you have to overcome the coefficient of static friction,
which is always more than the coefficient of dynamic friction.

An exception, in the case of some cylinder head bolts, is the use of
bolts torqued beyond their elasic limit.


The idea of those bolts is simply to ensure a more predictable clamping
force than can be obtained by measuring the torque applied. A torque
wrench doesn't measure the clamping force, at least not directly. Other
factors, dirt etc, can cause higher/lower torques to be applied by the
wrench to achieve the same clamping force.

The bolts, at least when new, are designed to 'go over' they limit
reliably. At that point the clamping force should be as expected.

That isn't ex Uni, it was explained to me by a tank mechanic. (Not the
water kind.) He was working on an M1A1 engine.

They're still very probably going to need less torque to undo than they
did to do up.

I disagree. They are torqued up until they yield, but they will work
harden so that when you stop, they are a bit stronger than when they
were "new". When you undo them, you still have static friction to
overcome, plus any contribution from corrosion or other mechanisms which
increase the adhesion between the surfaces.

On Wed, 07 Feb 2018 11:05:31 +0000, Dave Plowman (News) wrote:

I always use a thread sealer on all the bolts which go into ally.
Otherwise they are likely to corrode over the years. That thread sealer
also locks, so requires a lot more torque to undo - and does so with a
'snap'

I picked up some threadlock whilst in the accessory store the other day.
Didn't read the label carefully enough. It was a Locktite product (can't
recall the formulation number) and buried at the end of the instructions
it said, and I paraphrase: "use for permanent joints not requiring future
dismantling" so clearly much stronger stuff than I'd really wanted. :-/




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On Wed, 07 Feb 2018 08:51:58 +0000, Martin Brown wrote:

In reality corrosion tends to stick steel nuts and bolts together on
Earth which can make penetrating oil essential to get them apart.

Personally I've never had a single success with so-called penetrating
oils, not one time in 40+ years, not ever. The only thing I've found
that's guaranteed to work is heat; not just butane or propane heat, but
oxy-acetylene heat. Heat the ****er up till it glows bright orange and
away you go. Never known it fail.



--
This message may be freely reproduced without limit or charge only via
the Usenet protocol. Reproduction in whole or part through other
protocols, whether for profit or not, is conditional upon a charge of
GBP10.00 per reproduction. Publication in this manner via non-Usenet
protocols constitutes acceptance of this condition.

On 07/02/2018 18:01, Cursitor Doom wrote:
On Wed, 07 Feb 2018 11:05:31 +0000, Dave Plowman (News) wrote:

I always use a thread sealer on all the bolts which go into ally.
Otherwise they are likely to corrode over the years. That thread sealer
also locks, so requires a lot more torque to undo - and does so with a
'snap'

I picked up some threadlock whilst in the accessory store the other day.
Didn't read the label carefully enough. It was a Locktite product (can't
recall the formulation number) and buried at the end of the instructions
it said, and I paraphrase: "use for permanent joints not requiring future
dismantling" so clearly much stronger stuff than I'd really wanted. :-/

Is it actually a threadlock or a locking compound? I know that the
locking compounds are good enough to lock the drive wheels onto the
axles of a 5" gauge locomotive - without threads, splines or any sort of
pinning.

SteveW

On Wednesday, 7 February 2018 18:53:25 UTC, Cursitor Doom wrote:
On Wed, 07 Feb 2018 08:51:58 +0000, Martin Brown wrote:

In reality corrosion tends to stick steel nuts and bolts together on
Earth which can make penetrating oil essential to get them apart.

Personally I've never had a single success with so-called penetrating
oils, not one time in 40+ years, not ever. The only thing I've found
that's guaranteed to work is heat; not just butane or propane heat, but
oxy-acetylene heat. Heat the ****er up till it glows bright orange and
away you go. Never known it fail.

Are you using the wrong stuff? ATF is the best. Some people think WD40 is a penetrating oil, but it's not.


NT

On 07/02/18 18:53, Cursitor Doom wrote:
On Wed, 07 Feb 2018 08:51:58 +0000, Martin Brown wrote:

In reality corrosion tends to stick steel nuts and bolts together on
Earth which can make penetrating oil essential to get them apart.

Personally I've never had a single success with so-called penetrating
oils, not one time in 40+ years, not ever. The only thing I've found
that's guaranteed to work is heat; not just butane or propane heat, but
oxy-acetylene heat. Heat the ****er up till it glows bright orange and
away you go. Never known it fail.


Oh I have had some success with penetrating wotsit, but preferably after
heat...:-)




--
€œBut what a weak barrier is truth when it stands in the way of an
hypothesis!€�

Mary Wollstonecraft

On 07/02/18 18:53, Cursitor Doom wrote:
On Wed, 07 Feb 2018 08:51:58 +0000, Martin Brown wrote:

In reality corrosion tends to stick steel nuts and bolts together on
Earth which can make penetrating oil essential to get them apart.

Personally I've never had a single success with so-called penetrating
oils, not one time in 40+ years, not ever. The only thing I've found
that's guaranteed to work is heat; not just butane or propane heat, but
oxy-acetylene heat. Heat the ****er up till it glows bright orange and
away you go. Never known it fail.




I have seen that done on a nut that was basically a ball of rust on the
end of a Landrover wing mirror arm. Most impressive.

On 07/02/2018 16:08, newshound wrote:
On 07/02/2018 02:12, Roger Hayter wrote:
Brian Reay wrote:

On 07/02/2018 00:22, Roger Hayter wrote:
Dave W wrote:

On 06/02/2018 21:42, Chris wrote:

Hi,

Say I do a nut or bolt up to (for example) 120ft/lbs as checked by a
decent torque wrench in calibration, can that same nut/bolt be
undone by
the same amount of force, or does it take more - and if so, how
much more
and why?

I would guess more, because when doing it up it must be sliding, but
when undoing you have to overcome the coefficient of static friction,
which is always more than the coefficient of dynamic friction.

An exception, in the case of some cylinder head bolts, is the use of
bolts torqued beyond their elasic limit.


The idea of those bolts is simply to ensure a more predictable clamping
force than can be obtained by measuring the torque applied. A torque
wrench doesn't measure the clamping force, at least not directly. Other
factors, dirt etc, can cause higher/lower torques to be applied by the
wrench to achieve the same clamping force.

The bolts, at least when new, are designed to 'go over' they limit
reliably. At that point the clamping force should be as expected.

That isn't ex Uni, it was explained to me by a tank mechanic. (Not the
water kind.) He was working on an M1A1 engine.

They're still very probably going to need less torque to undo than they
did to do up.

I disagree. They are torqued up until they yield, but they will work
harden so that when you stop, they are a bit stronger than when they
were "new". When you undo them, you still have static friction to
overcome, plus any contribution from corrosion or other mechanisms which
increase the adhesion between the surfaces.


Roger hasn't considered the 'stress / strain' curve for, in this case, a
bolt being tightened.

The stress (tension/load), which acts along the length and provides the
clamping force- doesn't suddenly change in gradient at the elastic limit
(Yeild point). It changes, but only slightly. The bolt is then in the
plastic range, it won't return to its original length if undone. But the
stress either side of the Yield Point doesn't change dramatically. If it
did, the idea of deformable bolts would be flawed. If you continue to
tighten, then you will reach a peak on the curve, the Ultimate Tensile
Strength. Go further, and the stress decrease but, oddly, you will
eventually reach the Fracture Point where, unsurprisingly, the bolt snaps.

On Wed, 07 Feb 2018 19:04:33 +0000, Steve Walker wrote:

Is it actually a threadlock or a locking compound?

I'll have to take a closer look at it. Remind me this weekend if I
haven't answered that question.





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On Wed, 07 Feb 2018 11:09:07 -0800, tabbypurr wrote:

Are you using the wrong stuff? ATF is the best. Some people think WD40
is a penetrating oil, but it's not.

Well, a lot of folks swear by ATF + MEK or variants thereof. The only two
things WD40 is good for is spraying on HT leads to disperse any dew on
them, or else as a lubricant/coolant when turning aluminium bar on a
lathe.





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On Wed, 7 Feb 2018 23:28:54 -0000 (UTC), Cursitor Doom
wrote:

On Wed, 07 Feb 2018 19:04:33 +0000, Steve Walker wrote:

Is it actually a threadlock or a locking compound?

I'll have to take a closer look at it. Remind me this weekend if I
haven't answered that question.

Sounds like a 'Bearing and stud lock'?

Cheers, T i m

In article ,
Cursitor Doom wrote:
On Wed, 07 Feb 2018 11:05:31 +0000, Dave Plowman (News) wrote:

I always use a thread sealer on all the bolts which go into ally.
Otherwise they are likely to corrode over the years. That thread sealer
also locks, so requires a lot more torque to undo - and does so with a
'snap'

I picked up some threadlock whilst in the accessory store the other day.
Didn't read the label carefully enough. It was a Locktite product (can't
recall the formulation number) and buried at the end of the instructions
it said, and I paraphrase: "use for permanent joints not requiring future
dismantling" so clearly much stronger stuff than I'd really wanted. :-/

I used Scotchclad 776 since that's what Rover recommended for their all
ally V-8. Many years ago. It's an aerospace product. Difficult to get
though. Lubricates, seals and locks. Not sure some threadlocks seal so
well - there are some bolts on this engine that go into the water jacket.

I do know that without it, the small bolts to the waterpump *will* shear.

--
*If we weren't meant to eat animals, why are they made of meat?

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Cursitor Doom wrote:
On Wed, 07 Feb 2018 08:51:58 +0000, Martin Brown wrote:

In reality corrosion tends to stick steel nuts and bolts together on
Earth which can make penetrating oil essential to get them apart.

Personally I've never had a single success with so-called penetrating
oils, not one time in 40+ years, not ever. The only thing I've found
that's guaranteed to work is heat; not just butane or propane heat, but
oxy-acetylene heat. Heat the ****er up till it glows bright orange and
away you go. Never known it fail.

+1

--
*Why are a wise man and a wise guy opposites? *

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Cursitor Doom wrote:
On Wed, 07 Feb 2018 19:04:33 +0000, Steve Walker wrote:

Is it actually a threadlock or a locking compound?

I'll have to take a closer look at it. Remind me this weekend if I
haven't answered that question.

There are different types of Loctite. A spline sealer is different to a
thread one.

--
*Errors have been made. Others will be blamed.

Dave Plowman London SW
To e-mail, change noise into sound.

On 07/02/2018 18:53, Cursitor Doom wrote:
On Wed, 07 Feb 2018 08:51:58 +0000, Martin Brown wrote:

In reality corrosion tends to stick steel nuts and bolts together on
Earth which can make penetrating oil essential to get them apart.

Personally I've never had a single success with so-called penetrating
oils, not one time in 40+ years, not ever. The only thing I've found
that's guaranteed to work is heat; not just butane or propane heat, but
oxy-acetylene heat. Heat the ****er up till it glows bright orange and
away you go. Never known it fail.

I had one thread, a trunion, that seemed to seize with heat. I'm sure it
was worse afterwards. However the clearances might have been tighter.

I felt that the grease that may have been in the threads turned to soot
and made turning more difficult.

However that was a one-off and have seen heat assist removal of nuts
from bolts.

On 07/02/18 20:10, Tim Watts wrote:
On 07/02/18 18:53, Cursitor Doom wrote:
On Wed, 07 Feb 2018 08:51:58 +0000, Martin Brown wrote:

In reality corrosion tends to stick steel nuts and bolts together on
Earth which can make penetrating oil essential to get them apart.

Personally I've never had a single success with so-called penetrating
oils, not one time in 40+ years, not ever. The only thing I've found
that's guaranteed to work is heat; not just butane or propane heat, but
oxy-acetylene heat. Heat the ****er up till it glows bright orange and
away you go. Never known it fail.




I have seen that done on a nut that was basically a ball of rust on the
end of a Landrover wing mirror arm. Most impressive.

Low oxygen produces a reducing flame and turns the rust back to iron
(powder?) again


--
Labour - a bunch of rich people convincing poor people to vote for rich
people
by telling poor people that "other" rich people are the reason they are
poor.

Peter Thompson

On 07/02/2018 19:09, wrote:
On Wednesday, 7 February 2018 18:53:25 UTC, Cursitor Doom wrote:
On Wed, 07 Feb 2018 08:51:58 +0000, Martin Brown wrote:

In reality corrosion tends to stick steel nuts and bolts together on
Earth which can make penetrating oil essential to get them apart.

Personally I've never had a single success with so-called penetrating
oils, not one time in 40+ years, not ever. The only thing I've found
that's guaranteed to work is heat; not just butane or propane heat, but
oxy-acetylene heat. Heat the ****er up till it glows bright orange and
away you go. Never known it fail.

Are you using the wrong stuff? ATF is the best. Some people think WD40 is a penetrating oil, but it's not.

40th recipe fro a Water Dispersant is it not (or is that some sort of
urban myth?).

I use a ATF/acetone mix (50:50) it has never failed as a penetrant it
also (mainly ) gets used as a 'rust eater', it helps when you are
removing surface rust.

I agree heat will shift just about anything but engine bays etc are
not the place for naked flames

A decent nut splitter takes some beating

On 10/02/2018 08:35, Cynic wrote:
A decent nut splitter takes some beating


I've had good results with a wire brush to remove as much rust/crude as
possible. A good soak in penetrating oil- the trick is to leave it
awhile. Sometimes try to wriggle and apply more oil, leave again.

Then a sharp 'shock', a good tight socket or spanner and a tap on the
handle with a mallet etc. I now have an air wrench but haven't needed to
tackle a stuck nut, I suspect that would do the shock bit.

--

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Benefit or Personal Independence Payment when they don't need it? They
are depriving those in real need!

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In article ,
Cynic wrote:
A decent nut splitter takes some beating

Not much use on a bolt into a casting, though. ;-)

--
*Venison for dinner again? Oh deer!*

Dave Plowman London SW
To e-mail, change noise into sound.

On Sat, 10 Feb 2018 09:10:16 +0000, Brian Reay wrote:

Then a sharp 'shock', a good tight socket or spanner and a tap on the
handle with a mallet etc. I now have an air wrench but haven't needed to
tackle a stuck nut, I suspect that would do the shock bit.

Air wrenches vary enormously in their effectiveness. You could get a
cheap one for around 30 quid but if the nut's been done up to some
stupendous torque, it won't shift it. 1100ft/lbs works for just about
everything except the heavier commercial vehicles, but to get true output
of that level you're going to have to spend five times as much at least
IMHO.



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In article ,
Cursitor Doom wrote:
On Sat, 10 Feb 2018 09:10:16 +0000, Brian Reay wrote:

Then a sharp 'shock', a good tight socket or spanner and a tap on the
handle with a mallet etc. I now have an air wrench but haven't needed to
tackle a stuck nut, I suspect that would do the shock bit.

Air wrenches vary enormously in their effectiveness. You could get a
cheap one for around 30 quid but if the nut's been done up to some
stupendous torque, it won't shift it. 1100ft/lbs works for just about
everything except the heavier commercial vehicles, but to get true
output of that level you're going to have to spend five times as much
at least IMHO.

I bought an electric impact wheel nut remover from of all places Maplin -
on special offer. It runs off a car battery, and is about the size of a
big mains drill.

It spins up to speed then whacks the nut round. And continues this cycle
until free. Says it can produce the equivalent of near 300 lb.ft of
torque. It certainly worked on my crank pulley bolt without locking the
engine, so should be good for anything ordinary car related. Cost
something like 30 quid. Think similar can be bought on Ebay.

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On 10/02/2018 15:45, Cursitor Doom wrote:
On Sat, 10 Feb 2018 09:10:16 +0000, Brian Reay wrote:

Then a sharp 'shock', a good tight socket or spanner and a tap on the
handle with a mallet etc. I now have an air wrench but haven't needed to
tackle a stuck nut, I suspect that would do the shock bit.

Air wrenches vary enormously in their effectiveness. You could get a
cheap one for around 30 quid but if the nut's been done up to some
stupendous torque, it won't shift it. 1100ft/lbs works for just about
everything except the heavier commercial vehicles, but to get true output
of that level you're going to have to spend five times as much at least
IMHO.




I bought it more as, following a stroke, my right arm tires when doing
things like wheel nuts etc. I have a compressor as tyre points in
garages stop at 60psi and our motorhome needs 80 psi.

It wasn't that expensive and, so far, has done all I've asked of it.
I've not needed to tackle any 'stuck nuts'.

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are depriving those in real need!

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On Sat, 10 Feb 2018 17:20:55 +0000, Dave Plowman (News) wrote:

It spins up to speed then whacks the nut round.

That is a sound idea. Harnessing the energy of a flywheel accelerated up
to speed and then dumping it all into the problem nut via some sort of
clutch arrangement. Only limiting factor here is that an easy to use hand-
held device is not likely to have much accommodation for a hefty flywheel!



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On 10/02/2018 01:36, soup wrote:
On 07/02/2018 19:09, wrote:
On Wednesday, 7 February 2018 18:53:25 UTC, Cursitor DoomÂ* wrote:
On Wed, 07 Feb 2018 08:51:58 +0000, Martin Brown wrote:

In reality corrosion tends to stick steel nuts and bolts together on
Earth which can make penetrating oil essential to get them apart.

Personally I've never had a single success with so-called penetrating
oils, not one time in 40+ years, not ever. The only thing I've found
that's guaranteed to work is heat; not just butane or propane heat, but
oxy-acetylene heat. Heat the ****er up till it glows bright orange and
away you go. Never known it fail.

Are you using the wrong stuff? ATF is the best. Some people think WD40
is a penetrating oil, but it's not.

Â*40th recipe fro a Water Dispersant is it not (or is that some sort of
urban myth?).

Correct, it contains a propellant and a very thin, volatile mineral oil
which acts as a carrier for a thicker, less volatile one. On a wet
surface, the thin oil disperses water. It will also penetrate rusty
joints to some extent, though not as well as "proper" penetrating oil,
or various home brews. ATF is mostly just a thin mineral oil with a few
additives. There is enough of the thick oil in WD-40 to leave a coating
when the thin stuff evaporates. Wipe it on a sticky curtain track and
then claim it doesn't lubricate (it also helps by cleaning). It's not
ideal for things like clocks because the oil residue collects dust and
dirt. Less of a problem on cylinder locks because air doesn't circulate
around the "works" so much.


I use a ATF/acetone mix (50:50) it has never failed as a penetrant it
also (mainly ) gets used as a 'rust eater', it helps when you are
removing surface rust.

Â*Â* I agree heat will shift just about anything but engine bays etc are
not the place for naked flames