UOS Unless otherwise specified (UOS)
Unless otherwise specified (UOS) · Anotaciones de plano · ISO 1101 + ASME Y14.5
Example in plan
How to interpret it
On the drawing, “All chamfers 1×45° UOS” states a unless otherwise specified (uos) requirement.
What controls
Wording that introduces a general rule applying to the whole part except where a local callout says otherwise. It sets a hierarchy: the specific overrides the general. It is used for general tolerances, undimensioned radii and chamfers, surface finishes, treatments, edge conditions and inspection criteria. Its scope covers the entire part, which is why it is one of the notes with the greatest consequences and one of the least read.
How to verify
What gets inspected is each requirement the note imposes, using the method appropriate to that requirement: general tolerance with conventional instruments, radii with radius gauges, edges by visual and tactile inspection, finish with a surface roughness tester. In the inspection plan these general requirements should be broken out as characteristics in their own right, because otherwise nobody measures them: they are not drawn next to any dimension.
Common mistakes when interpreting it
- Not reading the notes block and applying general tolerances from memory or from a similar drawing.
- Thinking a local dimension with a different tolerance contradicts the drawing: that is exactly what the wording provides for.
- Forgetting the undrawn operations the note imposes, such as deburring, undimensioned radii or general finishes.
How to get it in the workshop / if it comes out of tolerance
Read it before programming, not after machining: that is usually where you find the general tolerance for every untoleranced dimension, the radius for every undimensioned corner and the edge condition. A note like this can add operations that are not drawn anywhere, such as deburring all edges or applying a finish to the whole part. And check whether the notes block is on another sheet of the drawing.
Parts rejected on dimensions that carry no tolerance on the drawing: the tolerance was in the general note. Rejections for sharp edges or missing deburring: this is usually where they come from too. If a local callout contradicts the general note, the local callout governs; if two general notes contradict each other, it is a drawing error and must be clarified before machining.
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