Setting Rings and Setting Master
These sizes of setting rings are specifically used to calibrate ingages, intrimiks, holtest and other inside micrometers and dial bore gages. The rings can be used to check and verify either the high or low range of most of these micrometers. The 1" ring, and larger, can also be used to calibrate the ID jaws of calipers.
Each ring will have the actual size stamped on it. This means that when you order a 1" ring, the item you get may be stamped 0.99998 inches. It would be very costly to manufacture rings exactly to the nominal value, and that's why you'll get something very close instead.
Rings of other sizes will not be available here. If you need something like 1.045" you will have to have them custom made. You may want to check with Starrett-Webber for starters.
The B&S rings offered below come with a manufacturer's certificate of accuracy and traceability to NIST standards. You can use the rings just as they are, because the manufacturer guarantees their accuracy. However, your quality system may require certification with data. You will have to send the rings to an accredited gage lab for this formality.
Those made by Mitutoyo come with a manufacturer's certificate, traceable to International Standards. International Standards are accepted in place of NIST by international agreement. You may have to convince your quality assurance department of this fact (let them look up the agreement signed by the U.S. government). The certificate is dated at the time of manufacture and may be several to many months old at time of purchase. You will have to decide if this is sufficient for your purposes. Otherwise, buy the setting ring and send it to an accredited calibration lab for certification.
Once a year you will have to have them re-certified, unless your quality system has implemented a shorter or longer calibration cycle. Chances are this happens exactly when you need to use the setting ring. It is best to plan ahead and to have someone else in charge of these annual calibrations. That way you will be able to blame that "someone else."
Calibration certificates are never included but the manufacturers guarantee the accuracy as stated in their catalogs and as reproduced below. If you need NIST traceable certification with data, then you will have to send these rings to an accredited gage lab. We have a partial listing of such laboratories on page 151.
Setting rings are not consistently available but, surprisingly, Amazon often has stock! They also offer the best prices (but you know that already). Click on the Amazon links below and find out.
Bore Gage Zero Checker
An easier solution for setting your dial bore gage or digital bore gage is to use the Mitutoyo Zero Checker.
You will require a set of gage blocks to equal the dimension you intend to measure. The gage blocks will be used to set the Zero Checker and then it is an easy task to set your bore gage to the same dimension.
Setting the bore gage dial to "zero" will then allow you to compare your work piece where any deviation from zero will be readable in the plus or minus direction.
You could also use the Zero Checker to calibrate the bore gage, again using gage blocks. You will need a block for the upper and lower end of the range for each contact point used with the bore gage. It may not be the ideal way to calibrate your bore gage but it will work within reason.
Gage blocks will have to be bought separately. See page 164