What masters do you use for your equipment?

viper · Dec 9, 2009

We typically use our micrometer standards to set our tools up and calibrate them. OUr calibration procedures have been accepted by all our customers but we are now getting into a few jobs where a couple tenths could really bite us so just curious what you guys use to calibrate your tools?
We would typically use our mic standards to set the mics, then use those mics to calibrate everything else. Problem is mics can be off by .0001" just by how many times you roll over the thimble ratchet. I wish I could decrease the clutch force on the mics but I do not think I can.

Eric M · Dec 9, 2009

If you read the thread about "Accuracy of Micrometer Standards", some of your questions may be answered.
The only way to truly verify the accuracy of your tools is to use gage blocks. They are made to a MUCH greater degree of accuracy than a micrometer standard.

The real Leigh · Dec 9, 2009

As Eric said, if you really want precision you have to use gage blocks.

Mitutoyo makes a gage block set specifically for checking mics, catalog #516-931 and other numbers depending on tolerance. I would suggest you buy one of these as a starting point.

- Leigh

viper · Dec 10, 2009

Thanks! I will certainly read the related thread and bring in some higher precision gage blocks. We have some now but I would not trust them. I guess I could have them certified too. I am not sure if that is expensive or not. Basically have a cert facility measure and certify blocks for use as calibration standards?

The real Leigh · Dec 10, 2009

viper said:
I guess I could have them certified too. I am not sure if that is expensive or not. Basically have a cert facility measure and certify blocks for use as calibration standards?

I recently got a quote from Starrett-Webber for calibration of the 9-block Mitutoyo set that I mentioned: $28.80.

I expect a standard 81-block set, having nine times as many blocks, would cost about nine times that amount.

But you certainly don't need a full 81-block set for checking mics.

- Leigh

machinistrrt · Dec 10, 2009

While the OP doesn't need an 81 piece set of blocks just to cal mics, I suspect he'd do well to obtain a good grade 2, 81 piece set. The current set of blocks should be limited to shop use.
Were I working to 3 tenth or tighter limits, I'd want better instruments than mics for measuring, as well.

gbent · Dec 10, 2009

I'm surprised anyone will accept any measurement that is not directly traceable back to the NIST. Especially since you are doing aircraft work. An inspection department starts with a calibrated set of gage blocks and a calibrated surface plate. IIRC, those calibrations are good for one year. With those two reference standards you can calibrate almost your entire shop.

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What masters do you use for your equipment?

viper

Titanium

Eric M

Cast Iron

The real Leigh

Diamond

viper

Titanium

The real Leigh

Diamond

machinistrrt

Stainless

gbent

Diamond

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