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A lesson on tolerances...

A lesson on tolerances...

RE: A lesson on tolerances...

Something is not right with this story.  
 - If this was important the cable could have been procurred in less time.
 - 2/100th of an inch =slightly more than 1/64th of an inch off.  To mitigate the problem its hard to believe they couldn't have made use of the larger cable.
 - Its a quasi government job ie results not as important as process

These, of course, are opinion, but this story has me slightly upset.

RE: A lesson on tolerances...

(OP)
As pointed out in one of the comments... this story needs a followup written by someone who knows the right questions to ask.

RE: A lesson on tolerances...

I think the federal government should step in and bail them out.

wink

RE: A lesson on tolerances...

A prime example of measuring with a micrometer, marking with a crayon, and cutting with an axe.

Incompatible tolerances.  Absurd.

RE: A lesson on tolerances...

You do that too?

Mike McCann
MMC Engineering

RE: A lesson on tolerances...

Mike...you've had almost as much to drink as I have!....you still have a couple of hours to make it up...go Brother.

RE: A lesson on tolerances...

When Cadd first got started years ago, we had dimensoned drawings from architects showing something like 32'-6 27/32". Personally, I have a hard time reading a 1/16" on a tape measure. Agree with Ron

RE: A lesson on tolerances...

Why on earth would you cut a trench/groove to that tight a tolerance. Wouldn't you just cut a 3" trench/groove and be done with it.

It's a cable at the end of the day.

RE: A lesson on tolerances...

The article said the "trench" was lined with steel.  Sounds like a fabricated steel tray rather than a trench.  But the journalist wouldn't know the difference.

RE: A lesson on tolerances...

Either way it's a construction job and not a precise machined component.  .02 is closer to 1/64th.

RE: A lesson on tolerances...

Maybe they should have used a grinder on the trench.  Sounds like too tight a tolerance.

BA

RE: A lesson on tolerances...

If the trench is lined with steel, isn't it the trench manufacturers fault for providing an inside diameter of 2.50" instead of 2.52".

Unless of course this is cast in place steel... winky smile

Anthony Deramo
American Bridge Company

RE: A lesson on tolerances...

If I told you to give me a 2 1/2" wide trench and you gave me a 2.48" wide trench, I wouldn't have a leg to stand on unless I said a 2 1/2" min.

If the company said a 64 mm trench and I gave them a 63.5 mm trench, do they have an argument?  (Perhaps 64 mm, min)  

RE: A lesson on tolerances...

Ron said, "A prime example of measuring with a micrometer, marking with a crayon, and cutting with an axe."

Can't those problems usually be fixed with a big hammer? (Particularly in this case!)

-- MechEng2005

RE: A lesson on tolerances...

I guess it is hard to push 2.52" O.D. cable through 2.5" I.D pipe.  

RE: A lesson on tolerances...

There is a lot of journalistic fluff in the article and very tiny or no science in it.

This is what happened when engineers/scientists read the news.

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