How to Measure to a MILLIONTH of an Inch (The Dawn of Precision) - Smarter Every Day 206

• [Destin] Radius gauges.
• [Darryl] Yes. If anything's missing it's because you probably--
• [Destin] What are you talking about?
• You probably misplaced it.

Hey, it's me Destin. Welcome back to Smarter Every Day. So this is my dad, and everybody's gonna talk about in the comments how ugly we are. Let's just get that outta the way.

• Chip off the old block.
• We're ugly.
• It ain't gonna get no better.
• We know it.

He knows how to measure things. He's been a metrologist for years and years and years, right?

• Yes.
• Yeah, what things have you measured?
• All kinds of things.
• Yeah?
• You name it, just this week I measured things that go into space and things that go down deep in the ocean.
• Just this week?
• Just this week.

And that's what a metrologist does, right? It's the study of measuring things. So, when I was growing up, this is the kind of stuff I would play with in the garage. These are micrometers; that's a really old lathe over there. These are things that kind of shape the way I think, and I read a lot of books back in the day, and I'm basically making this video because I want you to see it. It's the dawn of precision. You taught me all this stuff, and there's a guy named Joseph Whitworth.

• Mm-hmm, we're standing on his shoulders right now, right?
• Right, well I mean like, you like surface plates don't you?
• Oh yeah.
• Do you know who made surface plates?
• Who made 'em? I guess Mr. Starrett did.
• No, Joseph Whitworth.
• Did he?
• Yeah.
• Did he really?
• Yeah, so today on Smarter Every Day, I would like to go on an adventure to learn about this guy, Joseph Whitworth, and basically I think you will enjoy this video.
• Okay.

So our story starts here at the Tennessee State Museum. There's a really cool thing here, something I've cared about my entire life. It's a special weapon that was used in the Civil War called a Whitworth rifle. Okay, this is what we're here for, this is a Whitworth. This represents the proliferation of the idea of modern manufacturing precision. This is a weapon that was designed in England by a guy named Joseph Whitworth. The scope is off to the side so I don't really know how they fire this thing. Look at the end of the barrel here. You can see that it's not a circle like most rifles are at the end of their barrel. This is a hexagonal bullet. Now the interesting thing about that is it's a hexagonal helical bullet. If you think about it, how do you make a hexagonal hole in metal, and then how do you twist that at a certain rate? The answer is extreme manufacturing precision.

So there was a bullet at the museum, but the cool thing about the South is you can pick up the phone and call people like Preston who owns nashvillerelics.com, and you have a Whitworth bullet?

• [Preston] I do.
• [Destin] So your thing is Civil War relics, right? Like you've got all the--
• Yes.
• [Destin] You buy and sell the stuff, right?
• Absolutely.
• [Destin] But is your Whitworth for sale?
• Not yet. (laughter)
• [Destin] Well what's the deal here? You found this, right?
• I found that one.
• [Destin] Okay, so it has sentimental value to you.
• [Preston] It does. I've never actually sold anything that I found.
• [Destin] Really? So what's the story with this? This is what you'd call a drop?
• [Preston] This was a dropped bullet; it was not fired. It was found along the second day's battle lines at the Battle of Nashville. Basically it would've been dropped on December 16, 1864.
• [Destin] Really? You can peg it down to the day?
• You can peg it down to that day.

So what's so special about the Whitworth bullet, the hexagon right?

• The hexagon, a lot of the Whitworth's that came through were the round conical type shells. You didn't see a lot of the hexagon type guns come through, and it's quite rare to dig one and to find one in dropped great condition is kinda neat to find.

• [Destin] So why did the sharp shooters of the day prefer the Whitworth?

• Very accurate.

• [Destin] Really? Did you know they actually made artillery pieces that have the hex?

• I did, I did. I'd seen some of those shells. I've never seen the actual cannon, but I'd seen some of the shells.

• [Destin] I recently went to a civil war cannon shoot, and while some people were there on the field trying to knock down barrels with their cannons, there was this one guy that was absolutely drilling whatever he aimed at. How long did it take you to make this, Mike?

• [Mike] It took me a couple years. The planning and arranging stage took longer than the actual making of it. The making of it was about a year.

• [Destin] So the whole purpose of this is that you have an increased roll rate, so you have a more stabilized projectile, right?

• Correct.

• Wow, that's amazing. Okay, let's get the camera set up.

• [Man] That's perfect.

• Is that it? Oh, that's cool. That's really cool. That's gonna work.

• [Mike] It looks good, doesn't it?

• [Destin] It really does. Okay, here we go, Whitworth 600 meters, yards, yards. 600 yards.

• [Mike] Whitworth three powder ready to fire? Fire! (cannon boom) (explosion) (explosion flying through the air) (explosion) (explosion)

• [Destin] Did you hit it?

• Yeah, looks like I skimmed the bullseye at about nine o'clock.

• [Destin] Really? Oh holy cow, dude! We're talking about 600 yards?

• Yes.

• That's insane. So here it is right here.

• Aw man.

• Oh my goodness.

• Look at how aggressive that rotation is.

• Whoa!

• Wow!

• [Destin] Each one of those lands represents 60 degrees of rotation, so what we can do is we can go back and we figure out where one is in polar coordinates, and as it rotates we can actually calculate the roll rate and the distance. And we can calculate the distance or the muzzle velocity, based on the length of the round itself. (cannon firing)

• Whitworth was an engineer. He developed a lot of machining, unique machining abilities to make flat planes, to measure to a millionth of an inch; those were all original things that Whitworth engineered.

• A millionth of an inch. To show how this might work, let's look at this. So let's say we have a lever here, and we have 10 inches here, and we have one inch here to where we put a pencil or something like that. So if we move this thing 10 inches up top, we get one inch of movement down here. But what if we add another lever to this, exactly like that one. It's got a 10-inch fulcrum distance there, one inch of movement. Down here in the middle, that's a hundred thousandths of an inch of movement. Down here at the bottom, it's barely even moving. That's 10 thousandths of an inch. We have to zoom in so you can even see it.

Okay, it's one thing to understand these principles, it's quite another to actually incorporate them into the machinery of the day. That's the magic of what Whitworth did, and to explain how he did it, I'm gonna kick it over to a buddy of mine named Will. He has a YouTube channel called Machine Thinking. He actually went to the U.K. and shows exactly what Whitworth did to kick precision manufacturing into high gear.

• [Will] Thanks, Destin. Though it does seem incredible, Whitworth did make a machine that could measure down to a millionth of an inch. To make a machine this accurate and precise, he did something amazing. His machine had a micrometer screw with 20 threads per inch, which acted on the work piece that had a worm wheel with 200 teeth on the end of that shaft. In turn, the shaft had a dial divided 250 times. So 20 times 200 times 250 gives you a resolution of one millionth of an inch. Whitworth was able to show even a momentary human touch on the workpiece was detectable by this machine. Now this was before the times of environmentally controlled rooms, so I'm certain he was unable to get those same measurements day to day, but it does show he was able to measure to accuracies far beyond what anyone else was doing at the time. In fact, Whitworth is credited for introducing the thou, a one thousandths of an inch of measurement, and he could easily and regularly work to that kind of precision or beyond.

But you can't make a machine measuring close to millionths of an inch from just anywhere. There's a whole chain of important precursors to make something like that. Whitworth helped invent or improve those as well, probably the most important being the surface plate. The surface plate is simply a piece of cast iron or later granite, which is incredibly flat and serves as your reference for all precision. Whitworth helped popularize the method for making surface plates by scraping and lapping three pieces of cast iron together. The only plane that has come in between three or more surfaces has to be one that is practically perfectly flat, and it's from those flat surface plates that Whitworth could transfer that precision into other tools or machines like his millionth of an inch machine or cannons or rifles, and was able to help the world make precision a commodity like it is today. All the precision and accuracy in the world can be traced back to flat plates like the one that Whitworth made.

It's not initially intuitive, but even those precise hexagonal bores have their origins back in Whitworth's machines and tools, which got their precision and accuracy from his surface plates. The amazing accuracy of his cannons and rifles are just the end product of a very long chain of precision. But Whitworth didn't keep all this technology to himself. He eventually founded his own company, and he made precision machine tools for the industries that were starting to bloom thanks to this new level of precision. Whenever you have new kinds of precision and accuracy available to manufacturers, it enables new kinds of things to be made and products start to get cheaper. If you're ever eating a fresh strawberry in New York City in January, you have Whitworth partly to thank for that.

Whitworth's company made some of the absolute finest machine tools you could buy, including lathes, planners, drill presses, shapers, slotters and more, which gave precision manufacturing a huge kick. Whitworth died a wealthy man, and for his enormous accomplishments was given a title by the crown, but perhaps his biggest legacy was for another kind of machine he made, a screw cutting machine that he sold all over Britain. What that machine did, and the implications of it are amazing.

• If you wanna learn more about precision manufacturing, go check out Will's channel, Machine Thinking. Think about how important this stuff is. He's got some more videos coming about Whitworth and precision manufacturing, but this is important. Like Whitworth was the first person to standardize threaded fasteners, like threads per inch. He did that, it's called the British Standard Whitworth. Imagine going to a bolt bin here and trying to get a bolt, but nothing is standardized. He fixed that back in the 1840s. So do me a favor and look around you and see what's within arm's reach. If there's something made by humans around you, chances are there's a threaded fastener in it. So, leave a comment down in the video as to what that thing is; chances are it's a small fine thread machine screw, if I had to guess. Leave a comment and bonus points if you can name exactly what thread it is.

You went to Alabama right?

• Absolutely.
• Roll Tide.
• Roll tide.
• [Destin] Dude, every time I see you, you're over here sticking things in your barrel. What's up with that?
• Well, I have the luxury of cleaning the bore to an immaculate state, which helps with accuracy in an actual war situation.
• Dude's proud of his gun, that's what this is. Proud of your gun, that's exactly what's going on.
• That's right.
• [Destin] This is your baby, isn't it?
• It's like waxing my corvette.
• [Destin] It's called the Whitworth three plate method.
• I did not know that. I mean I knew the three plate method, but I didn't know Whitworth did it.
• [Destin] So Whitworth is like your hero.
• Yup. (laughter)