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Posted by Ignoramus29659 on June 14, 2008, 12:40 am
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Without naming names,I think that many of us can benefit from reading
the wikipedia article on impacts.
The torque applied to the bolt is the same, averaged over time, as the
torque transmitted to the operator. The key is AVERAGED. The torque
applied to bolts is HUGE but for short periods of time, and then zero
for much longer periods etween blows. Because the impact is heavy, and
is held in soft hands, the torque on operator hands is much more
continuous and, on average, not that huge.
Example: forget impacts at all. Suppose that I pound a steel plate
with a sledgehammer. The force on the plate may be equivalent to
several tons, but it is very intermittent. Force that is acting on my
body is much more continuous and is never more than a few dozen
pounds of force.
i
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Posted by Leon on June 14, 2008, 11:02 am
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> Without naming names,I think that many of us can benefit from reading
> the wikipedia article on impacts.
>
> The torque applied to the bolt is the same, averaged over time, as the
> torque transmitted to the operator. The key is AVERAGED. The torque
> applied to bolts is HUGE but for short periods of time, and then zero
> for much longer periods etween blows. Because the impact is heavy, and
> is held in soft hands, the torque on operator hands is much more
> continuous and, on average, not that huge.
>
> Example: forget impacts at all. Suppose that I pound a steel plate
> with a sledgehammer. The force on the plate may be equivalent to
> several tons, but it is very intermittent. Force that is acting on my
> body is much more continuous and is never more than a few dozen
> pounds of force.
In all seriousness, you should get your hands on a large impact and have
your wife film the event. You will "look" like a he-man, then let your wife
operate the tool and you do the filming. Don't show that one to your
buddies. ;~)
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Posted by Leon on June 14, 2008, 11:07 am
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>
>
> In all seriousness, you should get your hands on a large impact and have
> your wife film the event. You will "look" like a he-man, then let your
> wife operate the tool and you do the filming. Don't show that one to your
> buddies. ;~)
>
Might I add, be sure to actually have the impact doing work vs. just
spinning up.
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Posted by Robatoy on June 14, 2008, 2:51 pm
Please log in for more thread options >
>
>
>
> > In all seriousness, you should get your hands on a large impact and have=
> > your wife film the event. =A0You will "look" like a he-man, then let you=
r
> > wife operate the tool and you do the filming. =A0Don't show that one to =
your
> > buddies. =A0;~)
>
> Might I add, be sure to actually have the impact doing work vs. just
> spinning up.
Interesting thread.
The REALLY big bolts, are never tightened with an impact wrench.
The two halves of a steam turbine casing in power generation (hundreds
of thousands of horse-power) are held together with bolts. They are
tightened by hand. Really. Just a small 2-3 foot spanner. No impact
nonsense. Some bolts on the high pressure side are 3" to 4" in
diameter x anywhere to 18" to 24" long.
Tightened by hand. Un-done by hand. But there is a trick to it. A
hole, in the middle of the bolt, runs length-wise and is about 3/4" in
diameter. Therein lies the magic. Also, those bolts are polished at
the ends, which are very flat... for yet another reason.
But alas, I said too much already...
oooweeeeooooo
rrrrrr
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Posted by Larry W on June 15, 2008, 9:55 am
Please log in for more thread options <...snipped...>
>The REALLY big bolts, are never tightened with an impact wrench.
>The two halves of a steam turbine casing in power generation (hundreds
>of thousands of horse-power) are held together with bolts. They are
>tightened by hand. Really. Just a small 2-3 foot spanner. No impact
>nonsense. Some bolts on the high pressure side are 3" to 4" in
>diameter x anywhere to 18" to 24" long.
>Tightened by hand. Un-done by hand. But there is a trick to it. A
>hole, in the middle of the bolt, runs length-wise and is about 3/4" in
>diameter. Therein lies the magic. Also, those bolts are polished at
>the ends, which are very flat... for yet another reason.
>
>But alas, I said too much already...
>
Yes, the same setup is often used on ship engines, for example to
attach the cylinder head to the cylinder.
--
Often wrong, never in doubt.
Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf. lonestar. org
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> the wikipedia article on impacts.
>
> The torque applied to the bolt is the same, averaged over time, as the
> torque transmitted to the operator. The key is AVERAGED. The torque
> applied to bolts is HUGE but for short periods of time, and then zero
> for much longer periods etween blows. Because the impact is heavy, and
> is held in soft hands, the torque on operator hands is much more
> continuous and, on average, not that huge.
>
> Example: forget impacts at all. Suppose that I pound a steel plate
> with a sledgehammer. The force on the plate may be equivalent to
> several tons, but it is very intermittent. Force that is acting on my
> body is much more continuous and is never more than a few dozen
> pounds of force.