Unilateral Profile Tolerance

Ben1989 over 2 years ago

Hi all,

I have a unilateral tolerance that I'd like some gentle help with.

It has a 0.6 tolerance but with a negative offset. Am I correct in saying that this reduces the "nominal" position by 0.3mm essentially making it +0/-0.6? I understand I will not measure it to a +/- tolerance but just for my understanding of what it is asking for. Or, another way for my understanding, is saying that it cannot be oversized at all?

Also, what does the UZ mean? I know U means unilateral but I've not seen the Z before.

Any help would be appreciated.

TIA

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Matthew D. Hoedeman over 2 years ago

UZ, tells m that it is an ISO print. I THINK that the UZ (and the value following it) means a NOMINAL SHIFT and the direction & amount.

But don't quote me on that.
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Tater over 2 years ago

The UZ- means into the material. meaning the minimum size slot width is Nominal +.3mm. You want the slot big and whatever goes into the slot smaller than nominal for a clearance fit.
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Benedictj1 over 2 years ago

Yes it is ISO 1101, there is a sample in the HELP . Looks like .6mm unequal tolerance with .3mm in the minus direction to AB 'ALL AROUND" denoted by the circle on the extension / leader line
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Ben1989 over 2 years ago

So, as Tater said, is the offset supposed to make the slot bigger?
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vpt.se over 2 years ago

Hi all,

I have a unilateral tolerance that I'd like some gentle help with.

It has a 0.6 tolerance but with a negative offset. Am I correct in saying that this reduces the "nominal" position by 0.3mm essentially making it +0/-0.6? I understand I will not measure it to a +/- tolerance but just for my understanding of what it is asking for. Or, another way for my understanding, is saying that it cannot be oversized at all?

Also, what does the UZ mean? I know U means unilateral but I've not seen the Z before.

Any help would be appreciated.

TIA

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You are correct. +0/-0.6. Z is for zone.
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Matthew D. Hoedeman over 2 years ago

ARE YOU SURE? I know that for just U, with a negative value after, that means that one limit is -0.3, with a total zone of 0.6, so, -0.3 to -0.9 would be the zone as checked as a surface point.

The amount AFTER the U is how much "stock on" is allowed. SO, with a nominal size of 7, the the acceptable size would be 7.6 to 8.8 (AS A SIZE), but, the callout is for surface checks as profile, so -0.3 to -0.9 for individual points checked inside the slot.

BUT, it is ISO, not sure if it is different, as I said before, I thought UZ means a nominal shift of -0.3 (PER SIDE!), which would be different than the 'stock on' method. A nominal shift of -0.3 would mean that the 'middle of tolerance zone' size would be 7.6 (0.3 per side), the +/-0.3 AS A SIZE, not as a profile, which is what VPT stated.

They really need to get this stuff 'commonized'
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vpt.se over 2 years ago

The UZ value defines how much the center of the tolerance zone shall be offset from nominal.
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Matthew D. Hoedeman over 2 years ago in reply to vpt.se

yes UZ moves the zone (or offsets what the nominal should be), just a U is (American) different, the value after the U defines the 'stock on' tolerance limit. (which I said is what you stated, a shift, not a tolerance limit)
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Ben1989 over 2 years ago in reply to Matthew D. Hoedeman

So with a 0.3 offset making the slot "nominal" 7.6. Then applying a +/-0.3 limit (0.6) would then make the slot 7.00mm - 8.2mm. In my understanding at least
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Matthew D. Hoedeman over 2 years ago in reply to Matthew D. Hoedeman

yes, as a SIZE, but as points checked on the profile, it would be +0/-0.6 (for ISO UZ), but you need to check it as a profile per the print (individual points or a scan) and do a profile dimension. Which is stupid (IMO) as they also want it checked as a slot, so WHY didn't they just give it a +0.6/-0.0 size tolerance with the position callout?
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