What is the best gage equipment to measure an ID bore? Coordinate Measuring Machine?

[Dawn]

What is the best equipmenbt to gauge an ID bore; what gauge will give accurate Gage R & R studies as the best possible gauge? Is a Sunnen Gauge better than the CMM for ID's when there are problems with roundness?

[Dawn]

Can you tell me where I can get a 3-point bore gauge and how much?
Thanks, Dawn

DAWN,
THE FOLLOWING ARE ONLY MY VIEW POINTS FROM MY PERSONAL EXPERIENCE.
1) THE CMM WILL PREFORM ROUNDNESS BETTER
2) THE SUNNEN GAUGE IS NOT AS GOOD AS A 3-POINT BORE GAUGE.
HOWEVER THE BORE GAUGE WILL SHOW YOU WHERE YOU ARE OUT OF ROUND. IF YOUR CMM DISPLAYS GRAPHICS ON MULTIPLE POINT FEATURES. IT WILL ALSO SHOW YOU WHERE YOU ARE OUT OF ROUND.
3) THE BORE GAUGE SHOULD GIVE A BETTER R&R BECAUSE YOU CAN CONTROL THE POINT OF MEASURE EASIER.

DAWN,
MOST ALL OF THE MAJOR MANUFACTURERS CARRY 3-POINT GAUGING. BEFORE YOU RUSH OUT AND BUY REQUEST INFORMATION FROM SEVERAL OF THEM. DEPENDING ON YOUR PROCESS THERE ARE DIFFERENT TYPES OF 3-POINT MEASURE. DO YOU HAVE A MANUAL OR CNC-CMM? IF IT IS CNC YOU CAN CONTROL WHERE YOU MEASURE AND COULD DO SOME SAMPLING BEFORE INVESTING IN A GAUGE THAT MAY NOT BE NESSARY. CHECK ALL YOUR OPTIONS AND PRICING CAN BE DONE THROUGH YOUR LOCAL INDUSTRIAL SUPPLY HOUSE.

[Dawn]

Sunnen gages have 3 prongs and can measure tenths. Why would a bore gage be more accurate?

WHAT MODEL # SUNNEN ARE YOU USING?

[Wayne]

Originally Posted by Dawn

What is the best equipment to gauge an ID bore;

The first reply question is what is the tolerance of the bore? Product can be over measured. Given enough tolerance, GO/NOGO plug gages may be sufficient.

Originally Posted by Dawn

what gauge will give accurate Gage R & R studies as the best possible gauge?

Again the tolerance of the bore plays a part in determining "best" for this application. A CMM should not be used to measure a counterbore for a cap screw.

Originally Posted by Dawn

Is a Sunnen Gauge better than the CMM for ID's when there are problems with roundness?

Remember that not all out of roundness problems are bilobal. Some are tirlobal and others are multilobal. More than one measurement tool may be needed to determine the lobality pattern of the product. Once established, a tool designed to detect that specific defect can be chosen.

[Jim Wynne]

Originally Posted by Wayne/Gage Crib

Remember that not all out of roundness problems are bilobal. Some are tirlobal and others are multilobal. More than one measurement tool may be needed to determine the lobality pattern of the product. Once established, a tool designed to detect that specific defect can be chosen.

Very good advice, and I'll add the fact that the best way to avoid roundness issues in bores is to fix the process. Often there's an easy fix, as roundness issues can usually be traced to fixturing and/or tool wear problems.