Need help with measuring internal diameter

[C-Bag]

Wow. A lot of great responses. Seems like we all are learning.

I didn't want to get to deep into technique as writing about it is just going to confuse further. I wanted to give encouragement to practice and point out this is one of the many places you don't need more tools, just attention to technique and feel. I don't use my gauges everyday even though total experience is over decades. So it takes more attention than usual if I've not done it for a while as I'll forget all the details that have been pointed out. But once I'm "warmed up" it all comes back. Metrology is frustrating at first because we're dealing with such small tolerances and it can be hard to tell if it's tools or technique are the problem. No way to get around it except adapt and overcome.

 

[epanzella]

Using tools with "feel" is a funny thing. I'm a retired contractor and I remember teaching a greeny how to cut rafters exactly the same with a circ saw. At first they'd be a 16th off this way or that but after a few months most would be right on. When asked what they learned to go from "off" to "on" they had no answer. They just magically got better with apparently no more information than they had before. It's the same way with mikes and other gauges. You could know nearly all there is to know and not be very consistant, but as you do it day in and day out your brain, eyes and fingers get used to working as a team and you just start to get better. It's magic!

 

[Bob Korves]

You could know nearly all there is to know and not be very consistant, but as you do it day in and day out your brain, eyes and fingers get used to working as a team and you just start to get better. It's magic!

That is indeed true!

The problem is that many/most of us are HOBBY machinists, who never do it full time, and may not go back to any given technique or skill until the next time we need it for a somewhat similar project, which can be years apart, and quite possibly never again. So, we have to get our game brain on, prepare and refresh our memories, learn it from written text from a H-M posting or a YouTube video, new and outright if it is our first go at it (and hoping the advice is correct,) and all of this by ourselves much of the time. And that is quite a different thing than practicing it every day after being shown how to do it right by an experienced pro. We are doing well to at least get ourselves properly prepared for any dangers that come with the operation, much lest try to get it perfect on the first try or the first try in 10 years. Much of the advice we get is not even correct, and the genuinely inquisitive, curious, and cautious will have a lot better "luck."

 

[epanzella]

That is indeed true!

The problem is that many/most of us are HOBBY machinists, who never do it full time, and may not go back to any given technique or skill until the next time we need it for a somewhat similar project, which can be years apart, and quite possibly never again. So, we have to get our game brain on, prepare and refresh our memories, learn it from written text from a H-M posting or a YouTube video, new and outright if it is our first go at it (and hoping the advice is correct,) and all of this by ourselves much of the time. And that is quite a different thing than practicing it every day after being shown how to do it right by an experienced pro. We are doing well to at least get ourselves properly prepared for any dangers that come with the operation, much lest try to get it perfect on the first try or the first try in 10 years. Much of the advice we get is not even correct, and the genuinely inquisitive, curious, and cautious will have a lot better "luck."

You're so right Bob. I must have leaned to weld 20 times over my life but between stick, TIG and MIG, and the fact that I don't do this for a living, considerable time could pass between doing certain welding processes. What usually happens with me when I'm using some process that I haven't done in a while is I start out like a total hack and by the time I get decent again the project is finished!

 

[NortonDommi]

Looks like you need some windy roads. The midget I was thinking of was one of these: