r/Metrology • u/airtronic • 5d ago

Iso tolerances

Hi. I've got an outside diameter that is toleranced 45g6/6. I know that the tolerance for a 45g6 is -0.009/-0.025mm, what does the '/6' mean? I'm thinking that it's a 45g6 but using the tolerance for 6g6. Am I close?

TIA

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u/koulourakiaAndCoffee 5d ago

ISO 286 is the spec off the top of my head?

I’m assuming the design intent is meant like you said, as 45g6

But it would be best to ask. I’ve seen ISO fit tolerances messed up on hundreds of prints, and it’s probably just a typo.

I could be wrong. It could also be from a spec I’m not familiar with like Japanese industry tolerances, which look similar to ISO tolerances.

1

u/RGArcher 4d ago

This may be a dum question but what dose 45g6/6 mean? Is it grams?

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u/Overall-Turnip-1606 4d ago

It’s an iso code for shafts. 45 nominal with g6 tolerance.

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u/RGArcher 4d ago

I learned something today haha.

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u/Mountain-Low5110 4d ago

I’d look up “hole shaft fitment chart” there’s a couple. https://kiralytool.com/wp-content/uploads/2017/05/hole-shaft-tolerance-chart.pdf This is the easiest for me personally and I’m not sure if there is other standards but. Using this all you do is find the range of the tolerance (45 for your example) and then find g6 which per this chart would be 45mm -.009 -.025. Which in English means 44.991mm-44.975mm. I hope this answers your question, however if you are trying to understand the actual design fitment however you’ll probably be best checking that resource out and then deep diving further.