What is the best way to measure a .250 diameter hole +/.005 on an aluminum .030" thickness sheet? With a bore gage or a pin gage?

What is the best way to measure a .250 diameter hole +/.005 on an aluminum .030" thickness sheet? With a bore gage or a pin gage?

In my opinion, I would use a pin gage. I believe you will get a better measurement using this method, as there is not enough height in the thickness of the part to use a bore gage and get an accurate measurement.

Just my :2cents:

In my opinion, I would use a pin gage. I believe you will get a better measurement using this method, as there is not enough height in the thickness of the part to use a bore gage and get an accurate measurement.

I agree. The only issue with a pin gage is it is MMC. As long as roundness of the hole does not matter, you will be OK. If it does, then you need optical comparator, vision system or other such device.

What is the best way to measure a .250 diameter hole +/.005 on an aluminum .030" thickness sheet? With a bore gage or a pin gage?

You have to use a set of calibrated pin gauges with size intervals of 0.002mm between them.Or else a co-ordinate measuring machine with appropriate accessories which provide 0.001mm sensitivity.
V.J.Brahmaiah

You have to use a set of calibrated pin gauges with size intervals of 0.002mm between them.

If you have to simply measure the hole, .001" increment pins should do. But, if you want to do SPC on the hole, you need to know your control limits, and use the 10:1 on the distance between them - which will likely require .0001" pins. Again - pins are only good if the roundness of the hole is not significant.

If the hole is punched out, you also have less thickness to work with due to the break away. The recommendations above are good.

What is the best way to measure a .250 diameter hole +/.005 on an aluminum .030" thickness sheet? With a bore gage or a pin gage?

Just a one-time measurement or mass-production? This should also be considered in the selection of the correct device.

Stijloor.

Well, actually I am assessing the competence of our inspection department and one of the questions on the exam is the following:

Which of the following would be the most appropriate inspection tool to measure a machined, .213” dia. hole +/- .010, in a .030” thick stainless steel plate?

a. Micrometers
b. Gage pin
c. Calipers
d. Bore gage

This is one question I was not sure about the answer, a gage pin makes sense, the bore gage too accurate and calipers seem good enough for the +/-.010" tolerance.

Suggestions are welcomed.

Well, actually I am assessing the competence of our inspection department and one of the questions on the exam is the following:

Which of the following would be the most appropriate inspection tool to measure a machined, .213” dia. hole +/- .010, in a .030” thick stainless steel plate?

a. Micrometers
b. Gage pin
c. Calipers
d. Bore gage

This is one question I was not sure about the answer, a gage pin makes sense, the bore gage too accurate and calipers seem good enough for the +/-.010" tolerance.

Suggestions are welcomed.

It depends. If you need to know something about the roundness of the hole and you have a skilled operator, a bore gage would be the best tool. If roundness isn't an issue, a pin would probably be sufficient. If you're dealing with a clearance hole for a fastener (not likely given the odd nominal size and the fact that the hole is machined), calipers might be OK.

Well, actually I am assessing the competence of our inspection department and one of the questions on the exam is the following:

Which of the following would be the most appropriate inspection tool to measure a machined, .213” dia. hole +/- .010, in a .030” thick stainless steel plate?

a. Micrometers
b. Gage pin
c. Calipers
d. Bore gage

This is one question I was not sure about the answer, a gage pin makes sense, the bore gage too accurate and calipers seem good enough for the +/-.010" tolerance.

Suggestions are welcomed.

Calipers would suffice. However, when statistical studies must be conducted, you should use a device that is able to show you deviations in .001". A bore gage or intrimik (http://brownandsharpe.com/precision-hand-tools/internal/brown-sharpe-intrimik-internal-micrometers-9) are more appropriate.

Stijloor.

It depends.

That truly is the most correct answer! There is not enough information to properly determine if any of the list is adequate, based on some of Jim's responses.

Fact is, the MOST correct answer is ANY of the above gages that meet gage R&R for the dimension, and also measure the required dimension. For example, is MMC specified? Should be if you truly want to use pins gages OR you have qualified the process that capability shows the roundness is less than 10% of the tolerance (falls into gage error range).

Picking gages by tolerance rather than by gage R&R is a bad habit to get people into.

Also, is the Micrometers ASSUMED to be OD mics as a trick answer, or are ID mics, pin mics, etc. included in the micrometer family option?

However, when statistical studies must be conducted, you should use a device that is able to show you deviations in .001".

Actually , gages that measure 10:1 resolution to the control limits.

Folks,

Are we overanalyzing this thing relative to the OP's intended purpose of the question? ;)

Stijloor.

Are we overanalyzing this thing relative to the OP's intended purpose of the question? ;)

Nope - considering the audience of the test.

Nope - considering the audience of the test.

Simple questions require simple answers. Let the OP decide.
Ask a simple question at The Cove, and you're in for a treat! :mg:

Stijloor.

Folks,

Are we overanalyzing this thing relative to the OP's intended purpose of the question? ;)

Stijloor.

Note that the question changed in midstream; the OP first asked about a .250" diameter +/- .005 in aluminum "laminate" and now it's .213 +/- .010 in stainless steel. The only thing that's the same is the sheet thickness. We can only use the information we're given and try to provide the best responses we can.

Note that the question changed in midstream; the OP first asked about a .250" diameter +/- .005 in aluminum "laminate" and now it's .213 +/- .010 in stainless steel. The only thing that's the same is the sheet thickness. We can only use the information we're given and try to provide the best responses we can.

Agreed. :agree: But there's a tendency to make it more complex then needed.

Stijloor.

Agreed. :agree: But there's a tendency to make it more complex then needed.

Stijloor.

If the OP isn't sure what's needed, how do you know?

Simple questions require simple answers.

You are right, for backyard garage or a junior high shop class work just run with the calipers. If that is the scope of the question, I can go with that. But, I do not recommend that simplistic of a thought process in an industrial setting - especially to evaluate inspectors. I think framing the problems with the question is fair game and important for the OP.

...and the OP still can decide what to do with the info...

If the OP isn't sure what's needed, how do you know?

Intuition and the many years in this business. ;)

Stijloor.

Yes, I did changed the rules in the middle of the game, did not had all the right information at the time I posted the question, but it has been a real interesting thread. Thanks to all.

Yes, I did changed the rules in the middle of the game, did not had all the right information at the time I posted the question, but it has been a real interesting thread. Thanks to all.

Other than "interesting", were we able to answer your question? :D

Stijloor.

The thickness of aluminum sheet is only 0.03". Hence inserting a gauge could cause a slight depression of the sheet particularly when you are trying the pin gages one after another. Or even a deformation if one is not very careful. I would opt for an optical method for measurement - like a profile projector with micrometers (of accuracy 0.001) attached to x-y axes.

Well, as you guys have already noted, not enough information is given on the question to make the right assesment. But yes, you all have answered my question by given me valued information.