Unilateral Tolerance
Unilateral Tolerance
(OP)
I have a print with a dimension of 98,5 and it's tolerance is -0,3 and -0,2. I understand the ideas behind double minus or plus tolerancing. I do not completely agree with it but that is not the point here. Normally I am always used to seeing the max size on top and the min size on the bottom. This is not the case here. I am leaning towards this being a typo I will be checking with my customer on Tuesday, but I was wondering if anyone else has ever seen something toleranced like this. More than just the min size being on top another clue that leads me to thinking this is a typo is the other lengths on this part are toleranced +0/-0,5. The 98,5 dim is the OAL which does not appear to be critical.
Thank you in advance.
Bill
Thank you in advance.
Bill





RE: Unilateral Tolerance
Yes, typicality the nominal dimensions is between the high and low size. Your example looks like an ISO tolerance "ranges" to me, which "allows" this type of tolerating. In any case, I would not casually assume anything. Contact your customer to confirm your interpretation
Certified Sr. GD&T Professional
RE: Unilateral Tolerance
RE: Unilateral Tolerance
I regard double plus and double minus tolerancing to be a good idea. It shows off the required fabrication dimensions, and it shows off the as modeled size. I would assume that your dimension is an external feature, and that there is a hole dimensioned 98.5+0.2/0, or something like that.
Putting the smaller size on top is weird, and I agree with mkcski, that you should your customer and verify what they want.
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JHG
RE: Unilateral Tolerance
thanks again