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ISO 2768-1 Tolerance for radii

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chrisfp66

Specifier/Regulator
Jul 3, 2012
3
ISO 2768-1 appears to apply to two different types of radii. Radii NOT for broken edges with tolerances per table 1 and external radii that ARE for broken edges with tolerances per table 2.
My question is how is this difference specified on a drawing? How does someone reading my drawing know which applies? Thanks - Chris
 
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I think you are miss reading the Table 1 heading. Mine says: Permissible deviations for linear dimensions except for broken edges.
To me, Table 1 is for dimenesions betwen edges or form feature radii. Table 2 is for your chnmfers and edge breaks.

As to reading the drawing, you MUST specify which tolerance class you want your drawing to use. ISO 2768 is not enough. You must use ISO 2768-m or ISO 2768-mK, if you use ISO 27968-2, also.

Table 1 & 2 have a range chart that the values are designed for.


"Wildfires are dangerous, hard to control, and economically catastrophic."

Ben Loosli
 
Thanks for your reply Ben.

When I look at the scope of this document under note 3a it reads: "linear dimensions (e.g. external sizes, internal sizes, step sizes, diameters, radii, distances, external radii and
chamfer heights for broken edges);
It gives diameters and radii as examples of linear dimensions. I know one does not usually think of these as such but I belive due to the fact that they can be defined by two points (across a diameter or centerpoint od radius to any point on radius)they consider these linear dimensions.
Additionally it makes a distinction between radii and external radii for broken edges.
Therefore I believe table 1 applies to radii and table 2 applies to external radii (for broken edges). I am just not sure how the standard intends to differentiate between the two.

I greatly appreciate any input.

Thanks again - Chris
 
I see your point...Is the 3mm radius on the inner race of a ball bearing a design feature (table 1) or a broken edge (Table2)?

My answer would be a design feature because it is something that needs to be controlled as part of the manufacturing process.

A square plate with a 0.5mm hand grinder break edge would be Table 2. Not something that is usually dimensioned on the print, excpet maybe in the tolerance block as break all sharp edges 0.5 max.

I looked at the format from the company that we used ISO standrds at and we had ISO 13715 for fillet and radii dimensions. But I don't have a copy.


"Wildfires are dangerous, hard to control, and economically catastrophic."

Ben Loosli
 
A radius is a linear dimension as opposed to an angular dimension.

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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.
 
Then does everyone agree that table 1 of ISO 2768 is the applicable tolerancing for radii in general and table 2 is only applicable for radii that are for broken edges?
And is it to be assumed that a radii is toleranced by table 1 unless something on the drawing tells you to refer to table 2 (such as an ISO edgebreak drawing symbol or a drawing note or something)?

Thanks for any feedback - Chris
 
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