New calipers.......

[Engineer]

So we got some parts today that were 144" +-.002. They were 6063 U shaped extrusion .750 x .750 . Obviously somebody was smoking crack when they drew that up. Stuck a pin in the middle and measured both ways. I think I'm within .005 . I'd like to see them try and measure it..........

Do you do aerospace work or what?  I have to agree with Chris here.  The engineer is a zero. 

[fabr]

I'd like to see the verification that the calipers are that accurate and repeatable from one operator to another. I'm also pretty damn skeptical that humans are capable of not inducing whatever error to suit their needs  into calipers readings either. Accuracy of that level on pieces that large? Measured with calipers?  Repeatable? OK..................

[BDKW1]

Wait, the parts to small? Let me stick it out in the sun for a couple of minutes.........
 
I'm pretty sure their QC dept is going to check it with a tape measure. 
 

[BDKW1]

I'd like to see the verification that the calipers are that accurate and repeatable from one operator to another. I'm also pretty damn skeptical that humans are capable of not inducing whatever error to suit their needs  into calipers readings either. Accuracy of that level on pieces that large? Measured with calipers?  Repeatable? OK..................

Pretty much, On really high tolerance parts we either have the QC inspector and 2 other people measure it or put it in the CMM. Since this is too big for the CMM it got the measuring party. We were all within .005 of each other. I tend to always be on the small side, I push on the calipers too hard.

[fabr]

Pretty much, On really high tolerance parts we either have the QC inspector and 2 other people measure it or put it in the CMM. Since this is too big for the CMM it got the measuring party. We were all within .005 of each other. I tend to always be on the small side, I push on the calipers too hard.

And the next guy pushes more softly. There's no fricken way calipers are accurate enough for the specs.