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Doug, there are 2 parts to ISO 2768. -1 and -2. -1 refers to tolerances for linear and angular dimensuons without tolerance indications and -2 refers to geometric tolerances for features with individual tolerance indiscations.
So, in -2 you'll see that K is a tolerance class
Dear Steve ,
if on a technical drawing it is specified ISO 2768 mK , where should I look for knowing the tolerances ? In ISO 2768-1 m class or in ISO 2768-2 K class ?
thanks in advance
Just to add to what Steve has already mentioned:
ISO 2768-1 General Tolerances (linear & angular) has three charts, Linear, Broken Edge & Angular. Each chart is divided in four classes of tolerances as follows:
f = fine
m = medium
c = coarse
v = very coarse
The tolerance designation is determined by various items, such as size, complexity & means of manufacture of your parts.
ISO 2768-2 General Tolerances (geometric) has four charts, Straightness & Flatness, Perpendicularity, Symmetry and Circular Run-out. Each chart is divided into three classes of tolerances as follows: H, K and L. They are not literally defined in the specification, although I believe all letters from this specification are derived from Fit Tolerancing Charts ISO 286.
On our metric drawings we specify ISO 2768-m K
Thanks Steve and Eddie
Thanks for the info. It is starting to become a little clearer as to what impact this standard has on the way we manufacture I would hate for us to have our work rejected because we chose to ignore the tolerances