# Thread: Measuring tolerance of +/- 0.0003"

1. ## Measuring tolerance of +/- 0.0003"

Hi All,

I am a new member and having difficulties in measuring a cross drilled hole in a shaft. The requirement is to measure a hole with a +/- 0.0003", nominal dia on 0.1883 Any suggestion of how to measure this other than investing in a Air gauging equipment?

Thanks

2. I'm not aware of any alternative technology that has the resolution you need.

How many measurements do you need to make? Can you send the part out to a capable shop?

3. Hi Kelly,

Its for First Article, means that we will make about 10 parts. The problem with Air gauging method is that you will need a special Air Plug which has a nominal diameter for a specified hole. I doubt any shop will have the same exact dimension as required.

Thanks.

4. Gauge pins can be used as go/no-go gauges. Even if you have a custom go/no-go gauge made, it is cheaper than air gauging.

Timelord

5. But with a go/no-go method, wouldn't that physical gage also need tolerance of its own? Using the 10% rule, that means this gage would have a total tolerance of .00006, which might be another problem in itself.

6. First i m confused because the way you have mentioned sizes is kind of non-std (0 before decimal). are these limits in inch or mm?
.1883" = 4.78 mm i think TRI-O-BORE can be used to measure such size or if u have access to advanced tools like Mic-Trac, having accuracy below 1 micron

7. Originally Posted by mhk665
First i m confused because the way you have mentioned sizes is kind of non-std (0 before decimal). are these limits in inch or mm?
.1883" = 4.78 mm i think TRI-O-BORE can be used to measure such size or if u have access to advanced tools like Mic-Trac, having accuracy below 1 micron
Yes, SI (Metric) units are normally illustrated with a leading zero before the decimal and Imperial units (inch) are illustrated without a leading zero before the decimal.

However, notice that the number was given with a " following.

" = inch units

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