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# GD&T - How can i measure length in 0,1mm precision, near 2 meters?

## GD&T - How can i measure length in 0,1mm precision, near 2 meters?

(OP)
Hi,

I have to manufacture some aluminium plates within tolerance of -/+1,2mm's. Average plate size is 4sq meters. Given manufacturing drawing states ISO-2768-1 with "Class M" in tolenance section, but i don't know how to measure a 1954mm side of an aluminium plate in 0,1mm precision.

As we know, tape measure's precision is 1mm and longest caliper i found can measure 1000mm. Is there a way to measure and confirm 1962,5mm nominal edge length is in tolerance of -/+1,2mm's. If not, why ISO 2768-1 table 1 gives that precision?

Replies continue below

(OP)
Sample drawing.

### RE: GD&T - How can i measure length in 0,1mm precision, near 2 meters?

(OP)
Tolerance table that i have to stick in manufacturing and quality control:

### RE: GD&T - How can i measure length in 0,1mm precision, near 2 meters?

I was told you should take half of the smallest scale for the precision of a measurement instrument.
This means with a meter with 1 mm stripes, you are able to measure withing +/- 0.5 mm.
So +/- 1.2 mm should in practice not be a problem according to this logic.

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