Common Methods of Measuring the Diameter of a Hole

[TomG]

Here's a short video that I threw together on my lunch hour showing various methods of measuring the diameter of a bored hole. Most of it is fairly basic and commonly known techniques except for the part showing how to use a telescoping gauge. I've noticed that very few new machinists and even a few experienced machinists on these forums actually know how to use one properly, so that was the driving force behind making this video.

Tom

[EdK]

That was great Tom. I did not know that's how you use a telescoping gauge.

Ed

[TomG]

You aren't alone Ed, the telescoping gauge seems to be one of the more misunderstood measuring tools around. Glad the video helped you out.

Tom

[Micktoon]

Hi Tom , very good video , explained really well thanks for posting , I hope you will do more on other similar topics.

Cheers Mick

[TomG]

Thanks Mick.

I have a pretty good list of ideas and am open to suggestions as well. I'm trying to stick to the basic concepts of machining for now.

Tom

[EdK]

How about a video on how to properly measure with a micrometer? And how to read one? I don't use one very often and I keep having to look on YouTube to refresh my memory on how to translate the numbers into something meaningful.

Ed

[TomG]

Funny you should mention that Ed, reading the micrometer was next on my list. When I taught machine shop, I used to teach how to read the micrometer by associating the divisions on the thimble and barrel to pocket change. The ones on the thimble were pennies (1-25), each of the four marks between the numbered divisions on the barrel were quarters (4) and the numbered lines on the barrel were dollars. All you need to do is add 'em all up to get the measurement.

I'll need to check out the close-up capability of my camera, but I may be able to do that one right now.

Tom

[f350ca]

Good video Tom. With no formal training I never know for sure if Im doing things correctly, turns out I was using the telescopic guage right. Thanks

[TomG]

Thanks Greg, it never hurts to have a sanity check once in a while. I normally fail them, but it still doesn't hurt.

Tom

[Mayhem]

Thanks for that Tom. I had seen the telescoping gauge done similar but the instruction was to tighten the screw when on axis and then rock back off axis to get it out. I therefore thought that you screwed down tight, which I now see isn't correct. Perhaps I misunderstood those directions, but I found yours easy to follow.

I just have to remember not to tighten the mic up too much, as that tends to reduce the size real quick

I think you should dust off your old lesson plans from the 70s and turn them into instructional videos...