Magic Numbers and the Incredible improvement they provide! - 3D Printing 101

So, here's the thing. Nobody likes to admit when they're wrong, but I have no problem admitting that I don't know everything. I think one of the biggest problems in the world today, as far as scientific exploration and development of ideas for the future, is the fact that people have a hard time saying they don't know. So, I'm going to show you today something that I didn't know last week that I wish I had known this whole time. Stay tuned. Alright guys, let's talk about magic numbers. Here's the thing. Recently, I got into it a little bit with a guy over on Reddit, who actually, it turns out, was right. That's right. I have no problem admitting I was wrong. Let me explain to you. So, when I initially set up my Ender 3, the original file that came with it printed perfectly, and then everything else I sliced and tried to print came out like crap. So it took me about two, three, maybe even four days to get it dialed in and find a setting, a profile that actually printed nicely on this guy. So, I messed around with all the settings. Everything from the infill, to the percentage, to the flow rate, to basically the layer thickness. What I found was that I could pretty much only get prints at one height, and that was set 0.15 millimeters. Now don't scream my head off, I know that sounds weird to you people, okay? That might seem normal to you. It might seem extremely strange, because anybody who's had an Ender 3 for a while knows that the Ender 3 does have a magic number, and it's 0.04 millimeters. And the 0.15 that I was using was not a multiple of 0.14. My prints were coming out okay, and I was completely unaware of the little details that I was missing because of that hundredth of a millimeter. So, coming up in this video, I'm going to show you a couple of models that I printed, both at 0.15 and 0.16. I'm going to show you some of the differences in detail using only that one hundredth of a millimeter, and then we're going to discuss what a magic number is, and why they're so important. So, stay tuned guys. If you've never heard of magic numbers, you're definitely not going to want to miss this video. Alright, so here's the thing. For my test of these magic numbers, what I wanted to do was get the same model printed as close as possible using a magic number, and using a number that was slightly off. So, as I mentioned a minute ago, normally I've been doing things at a 0.15 millimeter layer height. And so far, my models have come out pretty nicely. I mean, if you look at Lightning here, he's got good detail on his wheels, there's no stringing. You can, though, see the layer lines pretty easily. So that, depending on which PLA I use, is different. I mean, I have a couple that come out really smooth at 0.15, and then I have this guy, which if I can get it to focus here, there we go, you see all the layer lines. There is a little bit of detailing in the window, and there's a little bit of a back window there. The gas cap is there, the tires are fine, Lightning's mouth is fine. All in all, a pretty decent model. If you look at the back, now this guy prints oriented like this, and that's the part that was stuck to the raft, and it is pretty nasty looking, actually. I also lost some of his spoiler. If you look at the other model, you can see it's quite a bit larger. I see we're a little bit better off in the shade here. One of the other things I wanted to point out that I thought was interesting, this is my 0.16 millimeter layer model, okay? This is, I mean, they seem identical, pretty close, but if you get a good look at them, you'll notice, like I said, the one with the magic number, the spoiler came out. The back doesn't look nearly as rough, actually. There's still a little bit of support need to be cleaned up there, but all in all, not bad. My biggest disappointment with the magic numbers was this. If you look, the bottoms of these two cars are pretty much identical. Now, this is the 0.15, and there is a little bit of fragmentation left over from the support stuck to my wheels, you can see, and then there's a little bit of fragmentation from where the supports went in there. But basically, if you look here, the pipes are not perfect by any means. But other than that, the rest of this is pretty clean, pretty nice. You get the same thing here, actually, where the pipes are a little bit frayed at the end. There is a little bit of that residue left from the supports on the wheels, but it is significantly less, which leads to less finishing time and probably a better product because it's not as lumpy. But of all the things I noticed that I almost missed, and the reason that I will actually be sticking to the magic numbers in the future, that shows me that it is actually a very big difference. Now, we're talking about 0.01 millimeters, and with that difference, the detail is staggering. Not only did I get this to come out properly with an extra hundredth of a millimeter, but if you look, hang on, let me focus here. You see this line right here, this ridge? Where is it at? That one hundredth of a millimeter difference resulted in that detail right there. That's a pretty fine line, guys. That's a pretty tiny detail. The difference between getting those tiny details in your model and having thin spots that come out properly instead of with holes in them that break is literally one hundredth of a millimeter. Depending on what your setting is set at right now, it could be a couple hundredths of a millimeter. I'm going to break this down for you now. We're going to do a little video, and I'm going to show you how exactly a magic number works and what it is because I was under the improper guise that the magic number was determined by your nozzle. In fact, it has nothing to do with your nozzle. After this discussion I had with this gentleman on Reddit, it became clear because he made it abundantly clear that the magic number actually has to do with your Z step. Your X, your Y as well, but more so your Z because that's the height that your printer can move accurately each time in a minimal step. Now that doesn't sound like it makes sense, but let me show you this video. All right, you'll have to forgive my lackluster animation. Basically what I wanted to show you here is that each stepper motor has four quadrants. As the motor is turning, it's going to turn on two, and then it's going to alternate the other two. So basically, let's say we're starting off here. When I rotate, when I move it, it's minimal step. The smallest step it can make, it's going to make a quarter turn. It cannot move an eighth of a turn. It won't stop here. It can move from here to here, and then it can move to here, and then to here, and then back to the original position. It can be fired backwards, so it can move in the opposite direction, but it's still going to move basically by a quarter turn. Now depending on the plane incline on your Z axis screw, the lead screw, it's going to turn a different amount. It's going to move up and down a different amount depending on the plane on your lead screw. Let's say we're talking about the Ender-3. If I flip over, do the minimal movement, I know that that's going to move this axis .04 millimeters. Then if I come back and I make a half a turn, then that's going to move my Z axis by twice the amount of a quarter turn. It's pretty obvious, so one, two. Now this isn't exact, this is just an example. If I were to take, if my quarter movement step is .2, and say I wanted to move something .5, in order to do that, I would have to make a quarter turn, and then another quarter of a quarter turn. I can't do that. The motor doesn't work that way. It's always going to revert to that quarter. Basically each time the motor turns a quarter turn, my axis moves by four hundredths of a millimeter. That's my magic number. I want my layer height to be a multiple of four hundredths of a millimeter. That's because I know if I move two turns, it'll move .08 millimeters. If I move three turns, it'll move .12 millimeters. Knowing exactly what your Z movement is capable of, the smallest step it can make, that's how you're going to get your magic number. It's not that simple. Every stepping motor isn't going to move every lead axis by .04 millimeters every time it makes a quarter turn because of that lead screw incline. It depends very heavily on how flat your incline is, basically. If your incline is more of an incline, a quarter turn is going to move you a lot further along the rod. If your incline is less, your quarter turn is going to move you a lot less along the rod. Now that we've taken a good look at this, I do have a formula I want to show you for calculating the exact magic number for any printer, but the two things you're going to need to know are the lead screw incline and what kind of stepping motor you have. We'll do that real quick. That's it, guys. That's going to wrap it up for our tutorial on magic numbers for 3D printing 101. I did put a link in the description down below that will lead you to a rather lengthy discussion, but at the top of that page is going to be the formula you need to get your own magic number for any 3D printer. You will need a couple of variables such as the lead screw height and what kind of stepping motor you're using. Definitely definitely check that out. I can tell you offhand that the Ender 3 is going to be a .04 millimeter layer height. That's the magic number, so any multiple of .04 will work great on the Ender 3. If you don't feel like doing the math or going through the formula, it's pretty easy to just Google the magic number for your specific printer. I definitely recommend you do that. You're going to want to be printing in multiples of that magic number from now on. That's it for this video, guys. Don't forget to hit like and subscribe. Thanks for watching, and I'd also like to shout out ThrowAwayForCause over at Reddit for setting me straight and teaching me something new. I'm always anxious to learn things I don't know, especially when it leads to a better print, so thanks again, ThrowAway.