Flatness Per Inch v.s. total area

Good Day,

Please advose regarding symbol/callout for flatness.

It is my understanding that = Flatness to .001 over entire surface. How is it written per inch? Or is it the other way around? ...can't find the reference in handbook.

Thanks!

It is flatness over entire surface.

Per inch is the same symbol but the call out would be .001 / 1.00 x 1.00

Thank you!

can be written different ways i often get flatness .0003"/12" and .0005" means
.
flat with no waves or milling pass laps or along path with waves of over .0003" over short distances of 12"
.
and flat within .0005" over total length of part which can be easily over 50".
.
short distance waves can be dull cutter or machine servo not holding steady. long distance waves can be
part deflection during machining or part warpage after material machined off
.
then there is the part 3 times longer than wide and they want narrow side within .0002" so when it sits on a
surface plate it shows long side it within .0006" perpendicular to surface plate. sometimes the narrow side
had a written spec of perpendicular and flat within .0005" but they meant to say when narrow side is the zero,
the long side needs to measure perpendicular and flat within .0005". for me it is what ever the quality
guys inspecting parts says is good and often drawing interpretation needs to remember what they will
accept as good

There's an ISO standard for Tolerances of form and position. Might be a good idea to invest a few $s.

Gordon B. Clarke said:

There's an ISO standard for Tolerances of form and position. Might be a good idea to invest a few $s.

Click to expand...

ASME Y14.5-1994/2009/whatever-revision is more common in the USA.