WEBVTT - The Boring Podcast 0:00:04.120 --> 0:00:07.200 Get in touch with technology with tech Stuff from half 0:00:07.200 --> 0:00:13.840 stuff works dot com. He there, and welcome to tech Stuff. 0:00:13.880 --> 0:00:17.960 I'm your host, executive producer, Jonathan Strickland, and I love 0:00:18.120 --> 0:00:22.759 all things tech. And in past episodes of tech Stuff, 0:00:22.840 --> 0:00:26.239 I have covered stuff like the history of subway systems, 0:00:26.320 --> 0:00:30.200 and I've given an overview of the Boring Company that's 0:00:30.280 --> 0:00:33.400 one of Elon Musk's companies and its mission to create 0:00:33.479 --> 0:00:36.920 underground tunnel systems beneath cities to allow for a new 0:00:36.960 --> 0:00:40.560 method of getting around town and also methods for getting 0:00:40.640 --> 0:00:44.880 between towns. So you've got the loop and the hyper 0:00:44.920 --> 0:00:48.000 loop concepts. But today I'm going to talk more about 0:00:48.040 --> 0:00:52.559 the enormous machines used to dig out tunnels as well 0:00:52.600 --> 0:00:54.279 as the smaller ones that are used to dig out 0:00:54.320 --> 0:00:58.200 smaller tunnels, the ones that are used for utility lines, 0:00:58.680 --> 0:01:01.720 or the ones that are really huge to make transportation tunnels. 0:01:01.920 --> 0:01:05.360 Those are gigantic, they're incredibly interesting, and they consist of 0:01:05.400 --> 0:01:08.960 multiple machines joined together to make a comprehensive tunneler. So 0:01:09.680 --> 0:01:12.560 this is a this is a big topic, both figuratively 0:01:12.680 --> 0:01:16.840 and literally. So first, let's talk about the challenges that 0:01:16.880 --> 0:01:19.920 we face if we want to dig a tunnel, specifically 0:01:19.920 --> 0:01:22.959 a tunnel under a populated area like a city. So 0:01:23.640 --> 0:01:25.280 we have to make sure that the method we use 0:01:25.319 --> 0:01:28.760 will not create structural problems for the region above. Right, 0:01:28.800 --> 0:01:31.920 we don't want any collapses. The tunnel can't create any 0:01:31.959 --> 0:01:37.600 welling or sink holes. Uh if it cannot undermine buildings. 0:01:38.240 --> 0:01:40.680 The method we use has to preserve the stability of 0:01:40.720 --> 0:01:45.720 everything else above it, or catastrophe will occur. Obviously, Likewise, 0:01:46.120 --> 0:01:49.440 the method we use needs to protect the tunnel that 0:01:49.600 --> 0:01:52.320 we're digging. We have to create a way to prevent 0:01:52.360 --> 0:01:56.480 the tunnel from collapsing in on itself. Through stone, maybe 0:01:56.480 --> 0:02:00.720 this requires a little bit of work just to force everything, 0:02:00.720 --> 0:02:02.920 but through soft earth you have to come up with 0:02:02.960 --> 0:02:05.160 something else. So there's got to be a mechanism to 0:02:05.240 --> 0:02:09.040 improve the structural stability of a tunnel. The machine we 0:02:09.160 --> 0:02:11.519 build has to be able to cut through lots of 0:02:11.560 --> 0:02:17.080 different kinds of ground, from sandy soft material to rocky surfaces, 0:02:17.240 --> 0:02:21.440 or dry material to wet mud. So the cutting edge 0:02:21.440 --> 0:02:24.440 of the tunnel er has to be capable of handling 0:02:24.520 --> 0:02:26.360 all of that, or you need to be able to 0:02:26.360 --> 0:02:29.720 swap out cutting edges depending upon the kind of ground 0:02:29.720 --> 0:02:33.160 you're going through, and that's easier said than done. Typically 0:02:33.639 --> 0:02:37.880 you just want to keep the same cutting edge on 0:02:38.120 --> 0:02:41.280 your your tunnel, or for the entirety of a dig 0:02:41.720 --> 0:02:44.760 you may have to replace little components on it, but 0:02:45.080 --> 0:02:47.960 that's a lot easier in the grand scheme of things 0:02:48.000 --> 0:02:51.800 than replacing an entire cutting head. We'll get more into 0:02:51.840 --> 0:02:53.680 that in a bit. We also have to have a 0:02:53.680 --> 0:02:57.399 way to remove all the material we're cutting or digging through. 0:02:57.400 --> 0:03:01.880 The excavated material, which is often called muck or spoil. 0:03:02.320 --> 0:03:05.160 All of that stuff has to go somewhere, so whatever 0:03:05.200 --> 0:03:08.080 method we use needs to take that into account so 0:03:08.120 --> 0:03:10.880 that we can manage all that mess as we keep digging. 0:03:11.320 --> 0:03:14.519 The digging mechanism needs a method for transporting the muck 0:03:14.760 --> 0:03:19.320 or spoil out from behind the cutting head and preferably 0:03:19.360 --> 0:03:23.919 out of the tunnel itself. So modern tunneling machines do 0:03:23.960 --> 0:03:28.400 these things in really interesting ways. There are differences between 0:03:28.440 --> 0:03:31.919 the various machines. They generally are doing the same thing, 0:03:32.000 --> 0:03:33.960 but they do it in different ways. Some are almost 0:03:34.080 --> 0:03:38.720 completely automated, others have a balance between human controlled systems 0:03:38.760 --> 0:03:42.600 and automated systems. The Boring Company posted a video that 0:03:42.640 --> 0:03:46.640 showed a machine apparently following the input of someone holding 0:03:46.720 --> 0:03:51.760 an Xbox game controllers. So that was interesting. Now, I 0:03:51.800 --> 0:03:55.280 don't know if that machine was actually following the directions 0:03:55.320 --> 0:03:57.880 of the person with the controller or the whole thing 0:03:58.000 --> 0:04:02.560 was an orchestrated video. It seemed to correspond with the 0:04:02.680 --> 0:04:05.600 person holding the controller, although that could have been a 0:04:05.680 --> 0:04:08.920 very well rehearsed routine and the person with the controller 0:04:09.040 --> 0:04:13.240 is just pushing the controls in different directions and hitting 0:04:13.280 --> 0:04:17.440 different buttons in time with something that has already been programmed. 0:04:17.440 --> 0:04:21.640 That's a possibility. I suppose there's no reason someone couldn't 0:04:21.680 --> 0:04:25.160 make an interface between a game controller and a huge machine. 0:04:25.640 --> 0:04:28.120 But then, considering the precision needed for some of the 0:04:28.160 --> 0:04:30.919 operations we're going to talk about, it does make me 0:04:30.960 --> 0:04:33.919 a little skeptical. I mean, it's possible that the video 0:04:33.960 --> 0:04:36.800 is completely legitimate, but I'm a bit concerned about the 0:04:36.800 --> 0:04:39.000 work the machine would be doing in that case, because 0:04:39.600 --> 0:04:42.600 I play Xbox a lot and precision is not one 0:04:42.600 --> 0:04:46.000 of the words I would use to describe the control system. 0:04:46.000 --> 0:04:50.800 But maybe I'm wrong. It's entirely possible. Now, Ideally, the 0:04:50.800 --> 0:04:54.640 device we create should be able to cut through the ground, 0:04:55.200 --> 0:04:57.680 shore up a tunnel as it does so so that 0:04:57.720 --> 0:05:01.680 the tunnel remains stable, move the spoil or muck from 0:05:01.760 --> 0:05:03.720 the dig so it's out of the way, and do 0:05:03.839 --> 0:05:07.599 so without disrupting anything above the ground. So how the 0:05:07.680 --> 0:05:11.600 heck is that possible? Well, first, the type of tunneling 0:05:11.640 --> 0:05:14.400 machines we use to drill the way for stuff like 0:05:14.560 --> 0:05:17.719 utility lines to subway trains or tunnels come in a 0:05:18.000 --> 0:05:23.160 range of sizes. Some are relatively small, and they're meant 0:05:23.160 --> 0:05:26.960 for digging tunnels that will house cables or utility lines. 0:05:27.680 --> 0:05:31.960 The company Robbins produces small tunneling machines that range from 0:05:32.000 --> 0:05:35.719 two feet or about sixty one centimeters up to six 0:05:35.760 --> 0:05:39.160 ft or one point eight meters in diameter. They make 0:05:39.200 --> 0:05:42.560 bigger ones too, but these are the ones that they consider, 0:05:42.760 --> 0:05:46.920 these small boring machines from two to six feet in diameter, 0:05:47.520 --> 0:05:51.640 and these machines actually rely upon another device. It's called 0:05:51.680 --> 0:05:56.279 an augur boring machine, which provides two things. It provides 0:05:56.320 --> 0:05:59.880 the rotational force that is used to turn the cutting head, 0:06:00.200 --> 0:06:03.560 which is the part of the tunneler that actually makes 0:06:03.600 --> 0:06:07.599 contact with the earth, and it also provides the forward 0:06:07.760 --> 0:06:12.200 thrust to push that cutting head against the earth, so 0:06:12.240 --> 0:06:15.320 that it is continuously making that contact and cutting away. 0:06:16.120 --> 0:06:19.680 The cutting face or the cutting head and the end 0:06:19.720 --> 0:06:22.800 of the augur can interlock with each other sort of 0:06:22.839 --> 0:06:26.640 like a socket wrench, and it's detachable sockets. So you've 0:06:26.680 --> 0:06:29.880 got the end of this auger blade coming in all 0:06:29.920 --> 0:06:33.920 the aug boring machine that connects it its sockets into 0:06:34.560 --> 0:06:39.280 the actual cutting head, and that's where you can transfer 0:06:39.360 --> 0:06:42.599 the rotational force from the auger boring machine to the 0:06:42.600 --> 0:06:45.840 cutting head, which spins like a disc on the other 0:06:45.920 --> 0:06:48.599 end of the scale. So that's the small side. If 0:06:48.640 --> 0:06:50.720 you want to talk big, let's go with the biggest 0:06:50.760 --> 0:06:54.080 there ever was, at least up to now. You've got 0:06:54.120 --> 0:06:59.920 something like Bertha. Bertha was the largest boring machine ever 0:07:00.200 --> 0:07:04.360 made so far. Anyway, the cutting face, that is the 0:07:04.760 --> 0:07:09.120 front of the cutting head, measured fifties seven feet in diameter, 0:07:09.480 --> 0:07:15.360 that's seventeen point four meters. The machines length from the 0:07:15.400 --> 0:07:18.160 face of the cutting head all the way to the 0:07:18.160 --> 0:07:21.840 back of the machine was three hundred twenty six ft 0:07:22.000 --> 0:07:26.360 or nine nine meters. While a small boring machine is 0:07:26.360 --> 0:07:29.360 an extension of an auger and it gets its rotational 0:07:29.400 --> 0:07:32.520 power and its forward thrust from this auger boring machine. 0:07:32.760 --> 0:07:37.000 Bertha was like a giant tunneling facility. It had a 0:07:37.080 --> 0:07:40.920 frame mounted behind the cutting head that housed stuff like 0:07:41.040 --> 0:07:44.040 break rooms and an operator office. So you had people 0:07:44.640 --> 0:07:49.560 walking inside this giant machine that had a shielded part 0:07:49.600 --> 0:07:52.080 in the front where the cutting head was, and then 0:07:52.080 --> 0:07:54.960 the part in the back was. It looked like a big, 0:07:55.000 --> 0:07:59.640 open scaffolded machine with lots of conveyor belts and these 0:07:59.680 --> 0:08:02.680 little rooms for for operator rooms and break rooms that 0:08:02.760 --> 0:08:06.680 kind of stuff. So the cutting head looks like a 0:08:06.720 --> 0:08:10.720 big disc with teeth sticking out of the face of it, 0:08:11.360 --> 0:08:16.520 and then behind that you've got this big cylinder. The shield. 0:08:17.400 --> 0:08:20.360 The shield is what protects the cutting head and the 0:08:20.400 --> 0:08:24.120 immediate part of the tunnel or from behind the cutting 0:08:24.160 --> 0:08:29.880 head and keeps the earth stable behind it, so it's uh, 0:08:30.120 --> 0:08:33.880 it's keeping everything from caving in essentially. Behind that, you've 0:08:33.920 --> 0:08:38.880 got an enormous um crane. More on that in a bit, 0:08:39.440 --> 0:08:42.960 and you also have a screw conveyor. A screw conveyor 0:08:43.120 --> 0:08:46.120 is kind of like an auger. It's got this helical 0:08:46.360 --> 0:08:49.560 screw that's designed to lift spoil or muck up to 0:08:49.640 --> 0:08:52.880 a conveyor belt. The conveyor belt sends all that muck 0:08:52.960 --> 0:08:55.680 back through the back of the machine and eventually completely 0:08:55.679 --> 0:08:58.400 out of the tunnel. All of these elements are mounted 0:08:58.440 --> 0:09:00.719 within this enormous metal for aim that's part of the 0:09:00.760 --> 0:09:05.160 tunneling machine. It's typically held into place by hydraulic legs 0:09:05.200 --> 0:09:08.040 that brace against the sides of the tunnel to keep 0:09:08.080 --> 0:09:11.800 it steady. The frame or maybe wheels as well. It 0:09:11.880 --> 0:09:14.560 could be wheels that are are locked into place. They 0:09:14.559 --> 0:09:17.200 have very powerful breaks and they just locked into place 0:09:17.320 --> 0:09:20.080 on the sides of these tunnels. Bertha was a special 0:09:20.120 --> 0:09:23.760 type of borer called an earth pressure balanced tunneling boring 0:09:23.800 --> 0:09:27.200 machine or EPB. I'll explain more about that and a 0:09:27.240 --> 0:09:31.240 little bit. So let's start with the small boring machines. 0:09:32.240 --> 0:09:34.880 A lot of the principles behind the small boring machines 0:09:34.920 --> 0:09:37.720 apply to the larger ones. That's just they're much bigger scale. 0:09:38.120 --> 0:09:41.440 So the drive for those smaller machines, as I mentioned, 0:09:41.520 --> 0:09:44.800 was an auger boring machine. Now, an auger is a 0:09:44.840 --> 0:09:47.360 tool that's a type of drill. Usually it has a 0:09:47.360 --> 0:09:50.080 helical bit, meaning the bit is in the shape of 0:09:50.120 --> 0:09:53.400 a helix, and the helical bit acts like a screw 0:09:53.440 --> 0:09:56.280 conveyor and It works on the same principle as an 0:09:56.280 --> 0:10:01.000 ancient piece of technology called Archimedes screw. And your typical 0:10:01.040 --> 0:10:05.559 Archimedes screw has a helical bit housed inside a pipe, 0:10:06.160 --> 0:10:08.839 and you don't have a whole lot of space between 0:10:08.920 --> 0:10:11.760 the screw and the pipe, so the screw is very 0:10:11.840 --> 0:10:15.040 snug inside this pipe. You can rotate it, but that's 0:10:15.040 --> 0:10:18.760 all you know. It's it's otherwise almost essentially making contact 0:10:18.840 --> 0:10:21.560 with the sides. It's very important for this. You set 0:10:21.559 --> 0:10:24.640 the screw at a forty five degree angle with the 0:10:24.679 --> 0:10:28.440 lower section immersed in water. So imagine you have a 0:10:28.480 --> 0:10:32.240 low body of water. You insert and Archimedes screw at 0:10:32.240 --> 0:10:34.920 this forty five degree angle into the water, and then 0:10:34.960 --> 0:10:38.600 when you turn the screw, it will lift or pump 0:10:38.880 --> 0:10:41.920 water out of the low end. As the water moves 0:10:42.080 --> 0:10:44.880 up the screw, it acts like a rotating ramp and 0:10:44.960 --> 0:10:48.000 it pushes the water up traps the water lifts it 0:10:48.080 --> 0:10:50.520 up to a higher elevation, so you can actually transfer 0:10:50.600 --> 0:10:53.400 water from a low area to a high area using this. 0:10:53.679 --> 0:10:56.760 You can build one of these yourself with a dowel 0:10:56.840 --> 0:10:59.800 and some plastic tubing and you just wrap the plastic 0:10:59.800 --> 0:11:03.800 two being around the dowel and a spiral, and when 0:11:03.840 --> 0:11:06.400 you put the dowel into water and you keep the 0:11:06.440 --> 0:11:08.760 dowel at like a forty five degree angle, as long 0:11:08.760 --> 0:11:12.240 as you're turning the dowel in the proper direction, it 0:11:12.280 --> 0:11:14.880 will continue to dip into the water, and that water 0:11:14.960 --> 0:11:17.840 will slowly make its way all the way up the 0:11:17.880 --> 0:11:21.560 coil as you rotate the dowel. Augers are used for 0:11:21.600 --> 0:11:25.320 all sorts of things. So wood drill bits typically have 0:11:25.520 --> 0:11:29.120 those helical grooves in them, and this helps convey shavings 0:11:29.160 --> 0:11:31.679 out of the hole that you're drilling and gets that 0:11:31.880 --> 0:11:33.960 those wood shavings out of the way so they don't 0:11:34.000 --> 0:11:37.080 just gum up the space. And you can use an 0:11:37.080 --> 0:11:40.760 auger to drill holes into the earth. The tunneling machines 0:11:40.760 --> 0:11:44.440 i'm talking about used augers for their rotational force and 0:11:44.480 --> 0:11:47.880 their ability to transport spoil out of a tunnel. The 0:11:47.920 --> 0:11:51.920 actual cutting head of these tunneling machines wasn't on the 0:11:51.920 --> 0:11:54.800 augur itself. It was a separate piece and it does 0:11:54.840 --> 0:11:59.000 the actual tunneling part. The auger boring machines sold by 0:11:59.000 --> 0:12:03.440 companies like Robin are large devices that allow for horizontal 0:12:03.640 --> 0:12:08.319 boring and they look like these big metal rectangular construction devices, 0:12:09.040 --> 0:12:12.960 and out of one end parallel to the ground is 0:12:13.000 --> 0:12:16.120 the auger blade. So to use one, first thing you 0:12:16.120 --> 0:12:19.400 would do is you would dig a pit down to 0:12:19.679 --> 0:12:23.120 whatever level you need so that where the tunnel is 0:12:23.160 --> 0:12:24.760 going to be. So you're gonna actually have to dig 0:12:24.800 --> 0:12:28.320 a pretty long and deep rectangular pit and get it 0:12:28.320 --> 0:12:31.240 down to the level where you're gonna dig this tunnel. 0:12:31.720 --> 0:12:36.959 And then you would put down tracks which the auger 0:12:37.679 --> 0:12:44.000 boring machine would sit on, and probably a concrete barrier 0:12:44.120 --> 0:12:48.560 at the back to act as a surface that the 0:12:48.600 --> 0:12:51.800 auger boring machine can thrust off of to start with. 0:12:52.720 --> 0:12:57.360 And that's your basic point of operations for the beginning 0:12:57.360 --> 0:13:03.120 of your tunneling process. The machine will provide the torque 0:13:03.400 --> 0:13:06.520 necessary for everything to work, and torque is a twisting 0:13:06.600 --> 0:13:10.320 force that tends to cause rotation. When you use a screwdriver, 0:13:10.760 --> 0:13:15.440 you are applying torque to a screw. With augur boring machines, 0:13:15.800 --> 0:13:19.040 torque comes from the rotational force created by the motor 0:13:19.160 --> 0:13:21.800 driving the auger And I've talked a lot about motors 0:13:21.800 --> 0:13:24.120 in previous episodes of Tech Stuff, So rather than go 0:13:24.240 --> 0:13:28.120 on through all that again, we'll just say it's a 0:13:28.160 --> 0:13:32.120 motor that creates the rotational force. The international systems of 0:13:32.280 --> 0:13:36.280 unit metric for torque is the Newton meter and Augur 0:13:36.360 --> 0:13:40.160 boring machine on the more modest side, might produce a 0:13:40.200 --> 0:13:43.559 peak torque of about four hundred newton meters or two 0:13:44.640 --> 0:13:47.680 foot pounds of force. I've got a lot more to 0:13:47.720 --> 0:13:50.360 say about these tunneling machines, but first let's take a 0:13:50.440 --> 0:14:01.559 quick break to thank our sponsor the honors. Rotational force 0:14:01.760 --> 0:14:05.640 transfers to the cutting head of this boring machine. These 0:14:05.679 --> 0:14:08.920 components make contact with what's called the cutting face of 0:14:08.960 --> 0:14:12.120 the dig that's the part of the earth or rock 0:14:12.320 --> 0:14:15.680 that the cutting head is actually making contact with. The 0:14:15.720 --> 0:14:19.360 cutting head is the surface that goes against the rocks, boulders, 0:14:19.360 --> 0:14:22.800 and sand. So this cutting surface can have numerous tools 0:14:22.840 --> 0:14:26.640 on it, including cutting disks which are used mostly to 0:14:26.760 --> 0:14:32.480 break up rocks and boulders, scrapers and other projections meant 0:14:32.520 --> 0:14:35.760 to remove material to excavate it, to break it up, 0:14:35.920 --> 0:14:39.560 excavate it and move it back into the back part 0:14:39.760 --> 0:14:44.000 of this tunneling machine. They also typically have gaps in 0:14:44.040 --> 0:14:47.800 the face of the cutting head that allows this spoil 0:14:47.880 --> 0:14:51.320 to pass through the cutting head and move back through 0:14:51.600 --> 0:14:56.040 the chain. Uh the spoil is able to come through 0:14:56.080 --> 0:14:58.720 that way, it encounters the auger blade that acts like 0:14:58.760 --> 0:15:02.600 a conveyor screw, and the auger blade will pull the 0:15:02.680 --> 0:15:06.800 spoil or muck away from the cutting surface. Now, not 0:15:06.880 --> 0:15:10.440 all cutting tools are suitable for all types of ground. Some, 0:15:10.600 --> 0:15:12.480 like the cutting disks, like I said, are really good 0:15:12.480 --> 0:15:15.400 for breaking up larger rocks and boulders into smaller pieces. 0:15:15.640 --> 0:15:18.080 But if you're encountering a lot of mud or water 0:15:18.320 --> 0:15:22.200 in this tunneling job, a different selection might be needed 0:15:22.520 --> 0:15:25.080 in order to dig the tunnel and to convey the 0:15:25.120 --> 0:15:29.320 material to the conveyor screw and maintain the cutting faces stability. 0:15:29.520 --> 0:15:32.680 Wet ground presents challenges in that regard. I'll talk more 0:15:32.720 --> 0:15:36.280 about that in a bit. So the cutting tools tend 0:15:36.280 --> 0:15:40.000 to be made from really really hard materials because you 0:15:40.040 --> 0:15:42.960 want them to last a good long while, preferably for 0:15:43.040 --> 0:15:45.960 the length of the tunneling job. So you might use 0:15:46.040 --> 0:15:49.480 something like tungsten carbide, and it's also sometimes just called 0:15:49.520 --> 0:15:52.880 carbide for short. And this is a pretty cool material. 0:15:53.320 --> 0:15:57.360 So tungsten is more than twice as dense as steel. 0:15:57.760 --> 0:16:01.840 The process for making tungsten carbide involves lots of steps, 0:16:01.880 --> 0:16:07.360 but essentially you're taking ore that contains tungsten, so something 0:16:07.400 --> 0:16:10.160 like wolf from right. Uh. So you take wolf from 0:16:10.240 --> 0:16:12.720 right and you crush it. You maybe you treat it 0:16:12.720 --> 0:16:15.400 with some chemicals, You heat it up, and you end 0:16:15.480 --> 0:16:18.760 up with something like tungsten oxide. Then you treat it 0:16:18.840 --> 0:16:21.800 in a carbonizing process, such as heating it to more 0:16:21.840 --> 0:16:26.240 than twelve degrees celsius. This removes the oxygen from that 0:16:26.360 --> 0:16:30.760 mixture and it binds carbon to the tungsten. Then you 0:16:30.800 --> 0:16:34.320 sort out the grains of tungsten carbide into piles based 0:16:34.320 --> 0:16:37.200 on grain size. You typically would use something like a 0:16:37.240 --> 0:16:41.200 sieve to do this. So you pass through sieves and 0:16:41.280 --> 0:16:43.560 you get the finest grains out, and then you go 0:16:43.800 --> 0:16:47.680 with progressively larger sieves to get the other grains. You 0:16:47.760 --> 0:16:51.960 mix that with some other materials, including cobalt. Cobalt connect 0:16:52.000 --> 0:16:54.960 as a binding agent. You press the mixture into a 0:16:55.040 --> 0:16:59.560 mold high temperature mold for the whatever tool you're building. 0:17:00.200 --> 0:17:03.160 Then you put it into what was called a centering furnace, 0:17:03.200 --> 0:17:05.960 which is hot enough to melt the cobalt, which then 0:17:06.000 --> 0:17:09.199 binds everything together kind of like the force. Then you 0:17:09.240 --> 0:17:13.240 remove the tungsten carbide you and uh then hone it 0:17:13.280 --> 0:17:15.800 down to its final size and its final shape. And 0:17:15.800 --> 0:17:18.199 I've skipped a lot of details here. Anyone who has 0:17:18.240 --> 0:17:21.280 worked with tungsten carbide, who's made the stuff knows that. 0:17:21.680 --> 0:17:23.720 But this is a very high level kind of look 0:17:23.760 --> 0:17:25.639 at the process. And in the end, what you have 0:17:25.800 --> 0:17:29.120 is a tool much stronger than steel that can stand 0:17:29.200 --> 0:17:30.679 up to a lot of wear and tear, which is 0:17:30.720 --> 0:17:34.480 perfect for cutting into stuff like stone and breaking up rocks. 0:17:34.720 --> 0:17:37.720 So the business end of the boring machine is the 0:17:37.720 --> 0:17:40.960 cutting head, and that's typically protected by some shielding that 0:17:41.119 --> 0:17:44.920 that sort of cylinder that's from the point of the 0:17:44.960 --> 0:17:49.200 cutting face and extends back quite a bit. And then 0:17:49.520 --> 0:17:54.720 sometimes you might use a length of pipe right behind that, 0:17:54.960 --> 0:17:58.880 especially if you're using cutting these utility size holes, then 0:17:59.000 --> 0:18:03.600 you would have metal pipe that would be connected to 0:18:04.240 --> 0:18:07.639 the cutting head and surrounding the auger blade. On the 0:18:07.760 --> 0:18:12.080 really big machines, it's typically part of the boring machine itself. 0:18:12.119 --> 0:18:16.040 You don't just have a cutting head that's extending from 0:18:16.080 --> 0:18:20.000 a pipe. It's all part of the same machine. This 0:18:20.160 --> 0:18:24.280 big shield that will extend back several feet. The shielding 0:18:24.680 --> 0:18:27.280 keeps the area near the face stable and it makes 0:18:27.320 --> 0:18:29.919 direct contact with the earth that you're cutting through, So 0:18:30.000 --> 0:18:32.320 it's it's sort of the tip of the tunneling machine. 0:18:32.440 --> 0:18:34.920 So the cutting surface of the toweling machine presses against 0:18:34.960 --> 0:18:38.400 the cutting face and turns it up to start digging horizontally. 0:18:38.880 --> 0:18:42.040 The pressure is generated by these in the small ones 0:18:42.080 --> 0:18:46.720 by the boring machine. It has those tracks I talked 0:18:46.720 --> 0:18:50.160 about that's laid down in the pit and it starts 0:18:50.200 --> 0:18:53.320 to roll forward, and the rolling forward is what puts 0:18:53.359 --> 0:18:57.480 the forward thrust against the the cutting head which makes 0:18:57.640 --> 0:19:01.240 contact with the the earth it starts to cut through 0:19:01.440 --> 0:19:04.240 and tunnel in. This is a very slow process. It 0:19:04.359 --> 0:19:07.360 is not happen quickly at all. So when I say 0:19:07.440 --> 0:19:11.000 roll forward, I really just mean putting forward pressure, forward 0:19:11.040 --> 0:19:15.240 thrust on that cutting head. Uh. The process itself takes 0:19:15.359 --> 0:19:20.359 quite a long time, and the auger is typically wheeled 0:19:20.640 --> 0:19:23.439 and has some sort of bracing technology to hold it 0:19:23.480 --> 0:19:27.840 into place so that it doesn't just push itself backward 0:19:28.320 --> 0:19:31.439 while it's trying to cut through this tunnel. Between the 0:19:31.480 --> 0:19:36.840 auger boring machine and the tunneler that you've you're using, 0:19:36.880 --> 0:19:39.480 you would lay down this metal pipe that contains the 0:19:39.520 --> 0:19:43.040 auger blade and it would attach to either end right, 0:19:43.080 --> 0:19:46.120 So one end of the auger blade attaches to the 0:19:46.200 --> 0:19:49.120 cutting head, the other end of the auger blade attaches 0:19:49.160 --> 0:19:52.600 to the auger boring machine. And then the auger boring 0:19:52.640 --> 0:19:55.919 machine starts to turn, the auger blade turning, the cutting 0:19:55.920 --> 0:19:59.840 head starts to tunnel into the earth. But obviously this 0:20:00.000 --> 0:20:03.359 only allows you to tunnel so far right. Eventually you're 0:20:03.400 --> 0:20:06.879 going to push the auger boring machine up against the 0:20:06.960 --> 0:20:10.880 point where the tunnel opens up. So what happens then? 0:20:10.920 --> 0:20:14.040 How do you go any further? If you're digging a 0:20:14.080 --> 0:20:16.280 short tunnel, obviously it's not a problem. But if it's 0:20:16.280 --> 0:20:18.840 a long tunnel, what do you do? Well, what you 0:20:18.880 --> 0:20:21.560 would do is you would stop the auger boring machine. 0:20:21.880 --> 0:20:24.520 You would you would stop your tunneling process. This is 0:20:24.520 --> 0:20:27.879 the cutting phase. You'd stop the cutting phase, and you 0:20:27.880 --> 0:20:31.879 would detach the auger boring machine from the blade and 0:20:31.920 --> 0:20:36.399 the pipe that it was pushing into the tunnel. You 0:20:36.400 --> 0:20:39.480 would pull the auger boring machine back to its starting position. 0:20:40.080 --> 0:20:43.960 You would then lower into the digging pit a new 0:20:44.119 --> 0:20:49.400 length of pipe inside, which is another length of auger blade, 0:20:50.440 --> 0:20:52.960 and then you would connect the two lengths of auger 0:20:53.000 --> 0:20:55.600 blade together the one that's already in the tunnel and 0:20:55.680 --> 0:20:58.119 the new length of auger blade that you've just lowered 0:20:58.160 --> 0:21:01.159 into the pit. You would connect the other side to 0:21:01.240 --> 0:21:04.960 the auger boring machine, and now you've essentially doubled the 0:21:05.119 --> 0:21:08.200 length of your auger blade and you can start up again. 0:21:08.680 --> 0:21:12.240 A full dig job might require you do this several times, 0:21:12.800 --> 0:21:15.440 and essentially you would keep doing it until the dig 0:21:15.520 --> 0:21:18.360 job was done. Uh, if the dig job was super long, 0:21:18.480 --> 0:21:21.200 this is problematic because eventually you're going to get to 0:21:21.240 --> 0:21:23.359 a length where the auger boring machine is not going 0:21:23.400 --> 0:21:26.200 to be able to generate the torque necessary to turn 0:21:26.600 --> 0:21:29.399 that long of a blade and the cutting head. But 0:21:29.480 --> 0:21:32.240 generally speaking, that's how it works. You just keep on 0:21:32.359 --> 0:21:35.800 lowering extensions into the pit, connecting it to the part 0:21:35.840 --> 0:21:38.960 that's already been pushed into the tunnel, and start up again. 0:21:39.840 --> 0:21:41.240 It's actually kind of neat. There are a lot of 0:21:41.320 --> 0:21:45.040 videos on YouTube that show this process. I watched tons 0:21:45.200 --> 0:21:47.879 of them because it was I don't know, I was 0:21:47.920 --> 0:21:51.240 turned into like a little kid again watching construction videos. Now, 0:21:51.240 --> 0:21:53.560 for the larger boring machines, the really big ones that 0:21:53.600 --> 0:21:56.680 are digging tunnels for like, you know, cars, or trains 0:21:56.760 --> 0:22:01.160 or whatever. There's a really cool method for building out 0:22:01.160 --> 0:22:04.680 a tunnel. These machines are way too big to draw 0:22:04.800 --> 0:22:08.040 thrust or rotational power from an auger boring machine. You 0:22:08.119 --> 0:22:12.600 would not have just a truly enormous auger boring machine 0:22:12.600 --> 0:22:16.800 outside in a deep pit. So instead they have all 0:22:16.800 --> 0:22:20.880 the mechanical elements incorporated into this enormous tunneler, and there's 0:22:20.920 --> 0:22:22.920 so many moving parts that it's hard to keep track 0:22:22.920 --> 0:22:26.119 of them all. They have their own rotational motor to 0:22:26.200 --> 0:22:32.120 generate that incredible torque needed to turn the cutting heads that, 0:22:32.480 --> 0:22:34.919 like I said, can be meters in diameter. Bertha was 0:22:35.240 --> 0:22:38.520 seventeen nearly seventeen and a half meters in diameter. You 0:22:38.560 --> 0:22:40.960 need a really powerful motor to be able to turn 0:22:41.040 --> 0:22:44.080 that with the force necessary for it to start cutting 0:22:44.119 --> 0:22:48.040 through the earth. Behind the cutting head, typically you have 0:22:48.119 --> 0:22:50.560 a chamber. There are a couple of different major types 0:22:50.560 --> 0:22:54.359 of tunneling machines, so these chambers can serve slightly different purposes, 0:22:54.720 --> 0:22:56.560 And I guess I should go ahead and break them 0:22:56.600 --> 0:22:58.399 down because it all has to do with the type 0:22:58.440 --> 0:23:02.479 of material your dig through. If it's pretty much solid 0:23:02.600 --> 0:23:05.000 rock you're digging through, you could use what's called an 0:23:05.000 --> 0:23:08.920 open tunnel boring machine. These do not have the protective 0:23:08.960 --> 0:23:14.120 shielding cylinder that extends back from the cutting head. They're 0:23:14.160 --> 0:23:19.080 just open because they're cutting through essentially stone, and they 0:23:19.960 --> 0:23:22.200 the rest of the machine is just straight behind it, 0:23:23.119 --> 0:23:26.600 unprotected for the most part, and the machine would use 0:23:26.720 --> 0:23:29.840 hydraulic grippers to brace against the walls of the tunnel 0:23:29.880 --> 0:23:33.480 it was building and to provide the forward thrust needed 0:23:33.560 --> 0:23:37.080 for it to make contact with the cutting face to 0:23:37.200 --> 0:23:41.040 keep on cutting crews behind it would add support systems 0:23:41.080 --> 0:23:44.040 to the tunnel like rock bolts and wire mesh, and 0:23:44.160 --> 0:23:47.720 that would help support the tunnel as it was being dug. 0:23:48.640 --> 0:23:52.359 But otherwise you don't have to have any additional stuff. 0:23:52.400 --> 0:23:54.800 You know, you you have like a conveyor to move 0:23:54.880 --> 0:23:59.480 the spoil away from the cutting head and down the tunnel, 0:23:59.560 --> 0:24:01.880 but otherwise eyes you don't need all the other bits 0:24:01.880 --> 0:24:05.600 and pieces. For soft ground, however, you might need something 0:24:05.640 --> 0:24:08.800 like an earth pressure balance machine. These machines have a 0:24:08.840 --> 0:24:12.119