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>> Frankly, if you're measuring something that's 10 meters across, do you
>> even *care* about the last 5mm? Probably not.
Depending on what it is, it's also probably going to change length with
temperature. For example a 10 metre bit of steel could easily be 5mm
longer in summer than in winter. Those 237 metre long trusses in the
other link could be 10cm longer. The system will be designed to cope
somehow with those changes in length, so the tolerances on those type of
parts is not that critical.
> Not if you are measuring it in cubits Otherwise that is a terrible
> tolerance. For instance the first breakthrough from the English to
> French side of the Channel Tunnel was 358 mm out over 22 Km.
That's cheating though, that's like making your 10 metre bit of steel to
a +/- 5mm tolerance, then filing it down to fit :-)
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From: Thomas de Groot
Subject: Re: How many digits of pi have you memorised?
Date: 17 Mar 2015 04:16:49
Message: <5507e2f1$1@news.povray.org>
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On 16-3-2015 20:52, clipka wrote:
> Am 16.03.2015 um 19:36 schrieb Orchid Win7 v1:
>
>> More like, this is probably the only chance I get to show off how much
>> free time I've invested in this pointless task.
>
> Not as much as other people, it would seem.
>
>>> (BTW, 3.1415 is all I can come up with on good days.)
>>
>> Frankly, if you're measuring something that's 10 meters across, do you
>> even *care* about the last 5mm? Probably not.
>
> I guess they might have cared here:
>
> http://en.wikipedia.org/wiki/Maeslantkering
>
or this: http://en.wikipedia.org/wiki/Large_Hadron_Collider
--
Thomas
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On 17/03/2015 08:02, scott wrote:
>> Not if you are measuring it in cubits Otherwise that is a terrible
>> tolerance. For instance the first breakthrough from the English to
>> French side of the Channel Tunnel was 358 mm out over 22 Km.
>
> That's cheating though, that's like making your 10 metre bit of steel to
> a ± 5mm tolerance, then filing it down to fit :-)
It did say later in the article that that tolerance would have been
unacceptable for a running line.
I didn't mean to imply that it was good. Although I think that it is.
;-) The horizontal miss was less than 60 mm.
It is amazing the fine tolerances people can work to.
--
Regards
Stephen
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> It did say later in the article that that tolerance would have been
> unacceptable for a running line.
> I didn't mean to imply that it was good. Although I think that it is.
> ;-) The horizontal miss was less than 60 mm.
That's nothing - my car went 1200 km once and ended up with a less than
60 mm miss at the end :-)
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On 18/03/15 08:21, scott wrote:
>> It did say later in the article that that tolerance would have been
>> unacceptable for a running line.
>> I didn't mean to imply that it was good. Although I think that it is.
>> ;-) The horizontal miss was less than 60 mm.
>
> That's nothing - my car went 1200 km once and ended up with a less than
> 60 mm miss at the end :-)
Was that an undershoot or an overshoot? The latter can be very expensive ;-)
John
--
Protect the Earth
It was not given to you by your parents
You hold it in trust for your children
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On 18/03/2015 08:21, scott wrote:
>> It did say later in the article that that tolerance would have been
>> unacceptable for a running line.
>> I didn't mean to imply that it was good. Although I think that it is.
>> ;-) The horizontal miss was less than 60 mm.
>
> That's nothing - my car went 1200 km once and ended up with a less than
> 60 mm miss at the end :-)
And my orange has a tolerance of half an apple. ;-)
--
Regards
Stephen
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From: Francois Labreque
Subject: Re: How many digits of pi have you memorised?
Date: 20 Mar 2015 10:40:09
Message: <550c3149$1@news.povray.org>
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Le 2015-03-17 15:53, Stephen a écrit :
>
> It is amazing the fine tolerances people can work to.
>
I had a teacher who used to work for Pratt& Whittney and told us the
story of building his house. He was so used to working with military
specs that he built his house with tolerances in measured in microns.
He says that on the first rainy day, none of the doors in his house
would close.
(I have a feeling i was making this up, as you can't get that kind of
precision with a circular saw... and I'm pretty sure he didn't use a
5-axis CMC mill to build his door frames.)
--
/*Francois Labreque*/#local a=x+y;#local b=x+a;#local c=a+b;#macro P(F//
/* flabreque */L)polygon{5,F,F+z,L+z,L,F pigment{rgb 9}}#end union
/* @ */{P(0,a)P(a,b)P(b,c)P(2*a,2*b)P(2*b,b+c)P(b+c,<2,3>)
/* gmail.com */}camera{orthographic location<6,1.25,-6>look_at a }
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> I had a teacher who used to work for Pratt& Whittney and told us the
> story of building his house. He was so used to working with military
> specs that he built his house with tolerances in measured in microns. He
> says that on the first rainy day, none of the doors in his house would
> close.
I suspect in the military they take into account things like material
expansion ;-)
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From: Francois Labreque
Subject: Re: How many digits of pi have you memorised?
Date: 21 Mar 2015 16:57:42
Message: <550ddb46$1@news.povray.org>
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Le 2015-03-20 12:02, scott a écrit :
>> I had a teacher who used to work for Pratt& Whittney and told us the
>> story of building his house. He was so used to working with military
>> specs that he built his house with tolerances in measured in microns. He
>> says that on the first rainy day, none of the doors in his house would
>> close.
>
> I suspect in the military they take into account things like material
> expansion ;-)
Yep. That's one of the reasons the SR-71 leaked like a sieve on the
ground.
--
/*Francois Labreque*/#local a=x+y;#local b=x+a;#local c=a+b;#macro P(F//
/* flabreque */L)polygon{5,F,F+z,L+z,L,F pigment{rgb 9}}#end union
/* @ */{P(0,a)P(a,b)P(b,c)P(2*a,2*b)P(2*b,b+c)P(b+c,<2,3>)
/* gmail.com */}camera{orthographic location<6,1.25,-6>look_at a }
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On 20/03/2015 14:40, Francois Labreque wrote:
> Le 2015-03-17 15:53, Stephen a écrit :
>>
>> It is amazing the fine tolerances people can work to.
>>
>
> I had a teacher who used to work for Pratt& Whittney and told us the
> story of building his house. He was so used to working with military
> specs that he built his house with tolerances in measured in microns. He
> says that on the first rainy day, none of the doors in his house would
> close.
>
> (I have a feeling i was making this up, as you can't get that kind of
> precision with a circular saw... and I'm pretty sure he didn't use a
> 5-axis CMC mill to build his door frames.)
I would guess that it is an exaggeration for comic effect.
And a face saver. :-)
--
Regards
Stephen
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