And this one, we’ll take a look at auto bed leveling and some of the sensors you can use to get it all working out of bed leveling and Marlin is great. When you get it set up correctly, there’s a couple different types of sensor you can use to enable this feature in this video. We’ll be using an inductive type sensor and a BL touch type sensor. You can also use a capacitive sensor or even a micro switch and the setup would be about the same for this setup. We’ll be using my Prusa clone because it already has an inductive type sensor installed and a print and Z build plate first. Let’s take a look at the specs on these sensors to get an idea of what we’re dealing with. Inductive sensors come in all shapes and sizes. A lot of these sensors will only operate in between 6 and 36 volts DC. The typical 3d printer board only puts out 5 volts. If you have a 6 to 36 volt sensor that won’t operate at 5 volts, you can add some resistors and directly cable it to the 12 volt power supply on the Prusik loan. I went with this 5 volt sensor that could be powered by a regular ramp sport. I’ll put a link to this sensor in the description below when you’re shopping around for inductive type sensors you’re gonna notice there’s NPN and PNP type sensors. NPN are triggered when you go to ground P and P are triggered when you go to a positive voltage. This can be controlled in Marlin by switching the in stop setting, so it doesn’t really matter which one you choose for this project. I’m using an NPN type. The first thing you should do is mount your sensor. There’s a lot of different mounts available on Thingiverse to fit almost every type of printer. The Prusik alone already has a spot for the sensor, so we’re just going to use that, Russo recommends starting with the sensor around the width of a zip tie close to the bed. I found somewhere around one. Millimeter is about perfect, depending on the sensor. You may need to adjust it up or down now for the wiring on a standard ramps board. These are pretty easy to set up. If you have a 5 volt sensor, you can cable it directly to the zi- in stop. I found on a lot of these sensors. The brown wire is positive. The blue wires negative and the black wire is the signal it can be different from sensitive sensor. So make sure to check the label. If you don’t have a standard grants board, maybe something like this, and you can still edit the Marlin from where you could more than likely still use. The sensor you’ll have to cable the ground and the signal wire to the negative Z N stop and then find power in another location again. You can use 12 volt power. If you add some resistors on the Bo touch, you’ll notice there’s a couple of extra wires, the brown red and orange wire to control the motion of the sensor while the black and white wire are your Z and stop signal and ground. The brown wire will go to the negative. The red wire will go five volt positive and the orange will go to the control signal. The white wire will go to the Z N Stop signal and the black wire. Go the Z and stop negative. When you set up the BL touch, it’ll have to be configured to be able to control the pop in and pop out of the pin also note, when mounting your BL touch. There’s a specific height that it needs to be at consult the BL touch manual to figure out the perfect height again. There’s a lot of mounts available for the BL Touch, Probably for your printer on Thingiverse remember? The inductive type sensor has to have something metal on the bed for you to use it. The print and Z build plate has a thin layer of copper inside it that allows it to work. You can also use an aluminum build plate with some glue. Stick on it, but you can’t use a glass sheet with aluminum tape on it. So what type of sensor Should you go with? Well, if you have a metal build plate? I definitely go with an inductive type sensor. These can be had for less than three dollars us on Aliexpress and they’re very accurate if you want to print on glass or some other type of material, go with a BL touch sensor. They’re kind of expensive, but they’re also very accurate now that we know a little bit about the sensors, how to mount them and how to wire them. Let’s get into Marlin and see how to configure it. Let’s start with the inductive sensor configuration first. Go to configuration dot H for this configuration. I’m assuming that you’re using a Rams board because that’s a very common type of mainboard. The first setting you’ll come to is minimum probe in stop inverting. If you have an NPN type sensor, you’ll probably want to set this to true for PNP. You’ll probably want to set it to false. If you do need to change the inverted setting to false, you’ll also have to set your Z minimum and stop inverting to false. You can’t have one without the other. The next section will be. Z probe options make sure defined Z minimum probe uses Z. Minimum in stop pin is uncommented. This is assuming you’re using the Z minimum in stop plug on your board. You’re also uncommented to fix mounted probe. This probe does not move, you’ll get to the Z probe offset settings. This wants you to tell. Marlon, where the location of the probe is. Our probe is roughly 23 millimeters to the right of the hot end and 10 millimeters behind the hot end. If it was in front of the hot end, it’d be a negative value. If it was to the left of the hot end, it’d be a negative value for now. We’re gonna set the Z offset to zero and we’ll calibrate that later. Now we head to the bed leveling section. This is where you select. What type of leveling you want to use? In this example, We’ll use Bilinear uncomment. Auto bed leveling bilinear. Then we’ll set how many points we want to probe on the bed. The default is 3 This means that it will probe three X points and three Y points a total of nine points to measure from next. You’ll want to set the boundaries for the probe. This is to avoid going off the side of the bed or crashing into a bed clip. I found staying roughly thirty millimeters inside. The actual build volume is a safe place to probe. You’ll have to measure your build surface and adjust these numbers accordingly. You also want to take a look at the Z safe homing option if your probe cannot safely home at zero? Y and 0 X. Then you’ll want to turn this on and zero in the middle of the bed. This allows printers that don’t home at zero zero to home safely again. This depends on your type of printer. The printer, in this example, homes at the corner of the bed. So we don’t need to turn this on. You’ll also want to put a comment in front of minimum software, and this is just until we can get the probe. Z offset configured correctly. Remember if you disable this setting, you can crash into the bed. This allows you to go into the negative below zero. So be careful, we can re-enable this. After we configure our offset after these changes are made, you can now upload it to the printer. Really, the only difference is with the. BL touch type sensor is you’ll comment out the fixed mount probe option and uncomment the BL touch option. You will have to change your probe location settings, but Marlin will pretty much take over from there and using a BL touch, you’ll probably want to change your Z minimum and stop inverting to false and your Z minimum probe and stop inverting the false with the newer versions of Marlin. The wiring is pretty simple as well on the BL touch. You want to plug in the white wire to the signal on the negative Z and stop and the black wire to the ground on the Z and negative in stop. Then you can hook the servo wires to the first servo port on the other side of the board. It’s the one right next to the button. Brown will be on the outside red in the middle orange on the inside the pins dot. H file is already configured for these servos Now. Let’s check and make sure the sensor is operating correctly. We’ll move the Z up. Enter an m1 1/9 command to see the in stop status. All the install should be open. Hold a piece of metal against your inductive sensor. The LED on this sensor should either go off or come on, then m1 1/9 again to check its status. The Zeeman is now triggered. The inductive sensor should be working if a BL touch sensor. When you turn the printer on the pin will cycle up and down that tells you the sensor is working and ready to probe now. Everything’s wired up either. Marlin is configured for your inductive type sensor or your BL touch sensor and it’s uploaded to the printer. Now we need to set the Z offset. At first. The Z offset settings were somewhat hard to understand because in Marlin, they give you this map and the Z offset says- is below and positive is above the nozzle. Well, that is true, but that’s assuming that your probe is fixed. Our probe is currently set one millimeter above the nozzle so by looking at Marlin, you’d think you would enter a positive value. That’s not true. This sensor is probably able to sense one millimetre, plus, so your offset is going to be a negative value from the nozzle location as you’re setting where the sensor is triggered. If you’re not getting a negative value, you need to move your sensor closer to the bed. We’ll start with a g28 command to home in the printer. Now enter a g29 command to run through the bed leveling process. Now move the printhead to the center of the bed d1 X 100 Y 100 feed rate 5000 move the printhead down slowly until it just touches the piece of paper the m11 for command to see where your Z offset is currently we’re at negative 0.5 6 Connect to Marlin for your Z probe offset from Extruder, enter negative point, five, six and upload now back to pronterface. Let’s do em 1 1 4 to check our location again home, the printer again g28 and g29 to run through the leveling process. Now let’s go back to the center of the printer g1 X 100 y 100 Z 0 be great 5000 Ike, again with your piece of paper now that we have a rough offset setting, Let’s go back to home and heat both the bed and the nozzle to printing temperature now that the hot end and better up to temperature. Let’s home again. G, 28 and run through the auto leveling procedure again J, 29 Now back to the center of the bed. G 1 X 100 y 100 Z 0 feed rate 5000 Check it with your piece of paper. Hitting the bed in the hot end has caused the gap to increase considerably. We’ll bring the printhead down slowly. Once again 1 1 4 to see the Z height, we’ve taken it down an additional point to disconnect back into Marlin. We want to add that value to our current offset value, but we need to leave some gap for the filament. Let’s call this value 0.65 and reupload! Now you can start a test print to make sure the first layer looks like it. Should you will need to add a g29 to your start G code in your slicer So that the printer will run through the auto bed leveling process? Every time you print the first layer should be low enough to stick to the print bed, But not too squished. If you need to get closer, the print bed increase the negative value of your offset. If you need to get further away, decrease the negative value of your offset, Here’s a side tip When you run the G 29 command. You’re gonna get a map of the points where the bed was probed. The numbers on the right or the right side of the bed numbers on the left of the left side of the bed. If you notice that, one side is much higher or lower than the other, you can use the G 29 to compensate for that. Violating your bed leveling doesn’t compensate very well for XQ. So if one of the sides is higher than the other, it’s gonna have a harder time leveling the bed, but you can use the G 29 map to decide which side needs to come down or which side needs to go up in our example. The right side is about two millimeters too high, so we’ll turn this side to the right. The lower the right side. If they were reporting negative values, you turn this to the left to raise it up g29 again. Now you can see the right side is starting to even out. If we turn the right side to the right a little more, we can get it even closer and there you go, that should get you started with auto bed leveling in Marlin. And you can say goodbye to those bed thumb screws. 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