Hack Your Prusa! - Prusa Bed Leveling - Chris's Basement

today we're going to take a look at a pretty interesting hack you can do to improve your bed leveling on your prusa 3d printer hello everyone chris here i hope you're all well and a couple of weeks ago friend of the channel sergio sent me a link to a video from ben gadgets i will leave ben's information in the description below so you can check out his content but basically what ben was doing was installing a modification on his prusa mark iii that added some nyloc nuts to the screws that hold the bed in place that way he could adjust the level in multiple points and it seemed pretty interesting to me so i wanted to check it out for myself now when doing a lot of these things i usually go digging around the internet just to see what everything's all about and most of the time there's always a ton of information about it and this was no exception and with just a bit of digging i was able to find the prusa owners github where they talk about this and the plug-in that they've written for octoprint we'll go into that more for sure and a step-by-step walkthrough that's been created on how to do this and what you're actually going to be doing to improve your bed level this photo included on that guide will kind of give you the idea of what we're getting ready to do here so i definitely want to check this modification out just to see how level i can actually make one of these beds but i also want to use this as an excuse to talk about bed leveling in general and see what happens when the bed is cold and we do the level and then as we get warmer just check out everything that has to do with auto bed leveling so let's start by taking a look at the prusa mark iii just to see what the bed's makeup is like so here's our mark 3 and this is what they call the mark 52 bed it has a removable steel sheet that's held on by magnets now the heater the actual bed portion of this is just a pcb and it's relatively thin and the whole thing is held onto an aluminum y carriage with these nine screws here's underneath just to get an idea of the carriage that we're actually dealing with this piece of aluminum right in here stock these plates just have spacers underneath here that are screwed down onto that carriage basically what we're going to do here is leave the center spacer intact as kind of a reference point and then all the rest of these spacers will be replaced with a nylock nut that way these screw heads can screw independently into that carriage effectively adjusting the bed up and down now we're talking about small measurements here but that can make a lot of difference when you're trying to print in a really large area on one of these beds now the mark iii has a lot of smarts built into it and it does a pretty good job at getting things corrected if there's any skew or something isn't quite level but those only go so far so i want to start with what prusa recommends so let's go ahead and run through the calibration on one of these just so i can show you what it does and that will give us a good starting point so when you buy a prusa kit you actually run through a wizard and set up a few things and do some tests but that also includes an xyz calibration and a z calibration so in the menu you can rerun your calibrate xyz i'm just going to do it here to show you what it does the first thing it does is auto home and then it sends the z all the way to the top these have tmc 2130s with stall guard so they know when the motors have stopped when it gets all the way to the top and it can't go any further that's how it knows it is level with the top of the machine and with your steel sheet off the printer is going to go around to four points on this bed and measure it with the pin to probe and check for skew at each point it goes back and forth and all around that spot just trying to test how sensitive that probe is to the spot so that it can tell if there's any skew on the printer and it'll do that in all four locations and after all four of those spots have been checked it will have you put your sheet back on so that it can do a bed level since we always print on a steel sheet from a mark iii you can probe anywhere on the bed not just specific spots now it goes through nine points measuring how far the probe is from this steel sheet to try to get a grid of what the bed map looks like and when you're all done it does give you some stats that you can look at if you go into the menu and go to support you can see your xyz calibration details so why distance from minimum that's telling you if there was any skew this way so is this edge further forward or further back than this edge that's what it was able to measure then the measured skew was actually 0.01 so not very much at all and it gives you some values of slight and severe that's how many degrees out it would be and this gives you the x and y point offset this gives you the information of that first point there in the front left corner how much the sensor thought it was off in front these are both positive numbers in front for the y and to the right for the x and again that process does do a pretty good job if you have your printer assembled correctly but we're just going by a few numbers that the prusa machine is kicking out it'd be much better if we could see what was actually going on and that's also part of this modification there's a plugin available for octoprint where you can run these bed level checks and then it will map the whole thing for you in fact there's a couple of different bed visualizer plugins that you can use and these visualizers are also available on the web you can just plug in your mesh data and it will show you that same graph so you don't have to use octoprint if you don't want to so the first bed visualizer that we're going to look at is just called bed visualizer the other one is tailored towards prusa and this modification but this plugin is really handy and all you have to do to use it is plug in a few things specific to your printer so we'll go to settings bed visualizer and it needs to know what commands you want it to run to gather this data but for most firmwares they already have it out there for you you can just click on this link right here today we're going to be doing everything on the prusa mark 3 so we're going to go with this g code right here we'll just copy it but if you have clipper prusa mini marlin use those so we just take that go back to our plugin and we paste it right in here now there are custom commands you can use with your g80 like the n the n will tell it how many probes to do now on newer firmwares for prusa you get a choice in between three by three or seven by seven we're going to look at both but we'll probably just change it manually so i can show you what to do it also gives you all the values when it does the level you can just look at it in the graph inside the plugin and it gives you angle corrections so if you're using an m3 screw down here like we're going to do to adjust it it tells you roughly how much of a turn and what direction to correct that which is kind of cool so it's a very useful plugin but let's just start taking a look at a couple of these so the first one i want to see is the bed cold the hot end cold and we're going to do 9 points and just so i can show you how to alter this on your printer it's available in the menu just go down into settings and you should have one for mesh bed leveling and here you can either set 7x7 or you can reset it to three by three let's start with three by three when we hit update mesh it's gonna home the printer and then build its nine by nine grid it probes the bed three times really quickly at each spot and here's our map now cold the bed looks pretty good remember this is a three by three grid nine points and we take three measurements on each one you can actually jump up to 10 points if you want to but this really isn't about how accurate the probe is this is about how level the bed is at different temperatures and what we can do about it and this plugin is pretty cool because you can save a snapshot it'll just download it as an image which is nice for reference later and it will let you edit the chart on a different website if you hit this pencil it brings it in gives you all the stats up here this is a pretty nice tool and like i said before you don't have to use octoprint to get all this information let me show you how to do it without octoprint just to get that out of the way if you don't want to use it so i'm just going to plug in the printer usb to my computer i'm going to open up pronterface and connect to the printer now from print to print the prusa will store this mesh so you can take a look at it if you want to but if you run a g28 w that should run a home without bed leveling so this will turn off mesh bed leveling so we'll run that command and the command to look at the mesh is g81 now it says mesh bed leveling not active now to run the probing sequence we'll just run g80 and then to look at it again g81 now you'll notice it's giving you the seven by seven grid even though we only run the three by three my guess is it's making some assumptions in between those probe points even though it's doing less probes but they're using the same grid pattern it should pan out to be almost the same thing 7x7 is definitely going to be more accurate but just take this whole grid and copy it we'll go back to the visualizer website and right here you can just control a to select all hit delete and paste in your grid and hit visualize and there's your graph and you can see it's really close to the one that we saw in octoprint it looks like it's even using the same engine but here's the visualizer then one more time here's the one we ran in octoprint so we're real close but this is just to show you that you don't have to use octoprint if you don't want to now on with the test so we're still doing the 3x3 nine point grid let's turn the temperature on the bed up to 60. now that we're up to 60 we're going to hit update mesh and it's going to do another probe sequence and there's our 3x3 at 60. you can see in the center things are starting to get stretched the corners are much lower so heating it up definitely makes a difference but what about at 100 c let's go up to that now that we're at 100 let's go again update mesh now and we're pretty close to where we were at 60. so it really doesn't seem to matter how much heat as much as just having heat we can take a look again here's cold here's 60 c and there's a hundred c and on these tools you can actually go around to each probe point remember it assumes a seven by seven but right here it's calling out a point three seven seven and on the 60c it is a 0.287 so it's actually affecting it a little more than i thought it would still an interesting result now even though these are assuming a 7x7 all the time no matter how many probes you're taking let's go ahead and do the same set of samples with the seven by seven grid so we'll go back into the menu and turn on the seven by seven settings mesh bed leveling seven by seven and we'll work backwards this time since we're already at 100c let's just update the mesh remember in your bed visualizer settings if you have any parameters adjusting the 3x3 versus the 7 or the number of probe points you need to update that the printer is not going to necessarily force them i'm just trying to show you both ways so we had it on n3 we'll switch it to n7 we'll save it then we'll update the mesh you can see it does a complete 49 point grid and this one is the 100c again we're working backwards it's probably a little better than the one at 60c we'll compare them all at the end let's jump down to 60c we're back down to 60. let's go ahead and update our mesh again the 7x7 is much better than the 3x3 but we'll go ahead and save it and let's go ahead and let it get down to room temperature which today is about 21c and we'll give it another shot just to see what it looks like so we're down in about the 23 degree range i think that's cool enough let's update our mesh and cold the 7x7 it's a little different let's save that one and we'll compare it to the original cold right here so the 7-7 is definitely doing a better job i know i said that once before but that's the way to go now i am curious about one more thing does it make a difference what temperature the hot ends at so let's just run one at 60c for the bed and 215 for the hot end to see if it's any different we'll compare it to our seven by seven at sixty and now that we're up to temp on hot end in bed let's run just one more time so there's our mesh this is the 7x7 60c bed hot end at 215 and this is the 60c bed 7x7 hot end off so room temp so there's a little bit of difference there so our testing going forward i say we leave the hot end on at the temperature we're going to print at i'm also going to do a print before and after just to see if we can tell any difference i took tom's bed leveling guide and just stretched it out we can measure it with some calipers maybe we'll be able to tell the difference in the corners but we'll give it a try and before we run that test print we're actually going to do the first layer calibration you usually have to do that if you do that xyz calibration it wants you to just make sure that the first layer is going to go down good but it's built in settings we go into calibration first layer calibration and you can do it with multiple filaments now we're just going to do it with pla we've got some pink so we can see it really well it's going to do a quick level and then it's going to start a test pattern so we can tell how our first layer is set it'll start at zero and then we can bring it down so the proper amount of squash is seen i usually like to just test it with my fingernail you can see it comes up with our layer adjust i know it's going to be a lot lower than zero so we'll just start in the negative you can tell because it's not actually sticking it won't make the corners so we'll keep going and let's check it right about point seven needs to come down some more point nine is some pretty good squish let's go nine 30. that should be good and at the end it prints a little square so you can kind of get an idea of what the bottom of a print would look like so there's our test patch probably just a little bit too much squish but it's really easy to adjust we can just back it out a bit and with the calibration out of the way we're ready to start our bed leveling test print and we're off so now we're done with our testing portion and i'm pretty happy with the results so heat and the number of points definitely makes a difference so we'll test that while we're doing our modification and hopefully we can do this test print and compare it with one after and there will be a difference so after this print we'll move on to our mod so we've got our before test print so here's what we're going to do we're going to take off the steel sheet and then we're going to remove all the screws that hold the pcb on then we're going to remove all the standoffs and note this mod works because we have the nine screws we're able to adjust it in multiple locations it probably won't on something like a mark ii i'm not sure on the mini but i think it has nine connections as well probably not a big advantage on the mini because it is smaller we'll just remove all these screws i'm going to back out the center one but i'm actually going to leave it in place for now before you start you might actually want to raise your z all the way up if you didn't know if you hold the button down for two seconds you can go right to moving the z i'm just going to move it all the way up now that everything else is loose i'll go ahead and pull this screw i just didn't want to move that stand off so i could show you what was underneath here but if you lift this up real careful you'll see there's nine standoffs one under each of those screws and we're just going to remove them all except the center one now using our stock screw we're just going to put it back on the pcb on every location except for the center one and then after you put the screw through i'm going to put a nylon three millimeter washer and then a nylock nut i'm gonna go ahead and get all of those started and there we have all eight of these in place now we need to tighten them up and what we're going for is we want the nut to be tight down on that nyloc washer but we want the whole assembly to rotate you don't want the screw moving at all but it has to be able to be adjustable when it screws into the y carriage so tighten them down and then maybe back them out about a sixteenth of a turn just a little bit i'll show you as we tighten these up there's the first one you can see i have the nut pretty tight down to that nylon washer those nylon washers are really going to help with this being able to move after you tighten them and it's tight the screw doesn't move but i can still turn the whole assembly and that's what you want now i'll do that to the other seven and there we go all eight are done and they're spinning freely but the screw is tight i would not want to do this without that nylock washer you don't want to mess up this pcb they're not cheap and it could cause a lot of problems if that nut actually dug into one of those traces so get some washers definitely but now this thing should be adjustable so we can put it back on but we need to be careful about how we torque this down so the goal here is we need to make sure all of these screws have the same tension my advice to you is to put all of these on and just get them started by about one thread just so they start to grip and leave that center one loose then we're going to go around clockwise each time and do one turn then after we do that a couple of times we're going to use one of the standoffs that we removed and judge how far the bet is from the y carriage metal i'll try to get you a shot of that but we're trying to get the height around the spec of this spacer and that way when the center one gets snug we'll know we're close to where stock should be then we can adjust from there so we've got one turn in all the way around let me show you underneath the bed here so our goal is to get these down back to stock height and we can use that spacer like i said before to kind of judge how far we need to go down so we probably need at least six seven more trips around the whole bed before we start to get close so just keep working clockwise on all eight of those screws remember only one turn you want to go slow and make sure everything's even we've been around four times we're getting there we've been around seven times and i actually can't quite fit the spacer under there it's pretty snug so we might have to back it out a bit but let's see if we can see where the center one is we want to make sure that center spacer is snug up against the pcb just by turning those outer screws we need to back these out just a bit because i think it's too snug but when the pcb can hold that spacer in there you can see it underneath then we can go ahead and put this last screw in but we don't have to get it super tight just enough so it doesn't move now we need to go around to all the outer screws and make sure we can slide that spacer underneath the y carriage in between the pcb so there we go i've been around to all eight locations used my spacer as kind of a feeler gauge if i were to guess i did about six and three quarters turns on each one of these i had to back them all out just a bit basically i backed it out slid the spacer in there turned it down just a bit until the spacer was a little bit hard to remove just barely touching it and then i called that good on all eight locations now we should be ready to use the app to try to help us judge if we need to make changes or not and that's why we're going to move to using this prusa leveling guide plug-in these are meant to be the locations of the screws on the bed and you'll see after it runs but this is going to try to tell you how much to turn each screw to get it back into level it's a pretty clever design and they also give you this preheat option it will pre-heat for you before we do the test level so let's go ahead and begin adjustment this will start the preheat we can put our steel sheet back on we'll need that for leveling and remember we decided to go with the hot end warm and the bed we're going to do this at 215c on the hot end 60 on the bed and we're using the 7x7 level the preheat is complete now it's going to do the mesh level it's assuming that your center screw is zero that way you can adjust up and down from there it might not be zero they just call it zero because it's the only one you can't adjust so the preheat completed and it went ahead and ran the level now it only did the 3x3 grid but remember it fills up that whole 7 grid for you it just fills in the numbers but these are the values we came up with and it's telling you which way you need to turn whether you need the bed to go down or up so in the front right we need to come up quite a bit it looks like on the whole right side we need to come up a bit and then down a little bit on the left side you can even have it recommend the number of turns you need to make you can switch to fraction turns so three quarters of a turn on this one and before we make any screw adjustments let's jump back over to bed visualizer and have it tell it what it sees and you can compare those results from what we saw it is quite a bit lower here on the right than it is here on the left so let's go ahead and save this one and let's go back to the prusa plug-in and we'll try to make some adjustments so the front right corner was definitely the lowest let's back it out just a bit and let's just play with a little and see how much measurement we actually get out of this so i'm going to give the front one a half turn because it was at .36 this one was at point 16 so let's give it a quarter turn and this one was point 15 so how about another quarter turn maybe a little less just to see how it changes as we try to adjust the bed this front one was .09 low so i'm just going to back it out a little and the back one was 0.05 too high so i'm just gonna nudge it down a little and it's probably wise to make really small adjustments on these but these were all just a little bit high this is a zero seven zero eight zero nine so let's snug them down just a bit just to see how they're going to change in the tool so we made some adjustments we're still preheated you can just hit continue and it'll run the cycle again it's kind of nice because it does move the printhead out of the way when it's done running it after that first correction i actually had to hit continue a couple of times to get it to populate correctly but now we're actually just a little bit too high on the right side so you can see how temperamental these adjustments are going to be also if it makes more sense to you to see them on the bed you can click this button and it'll show you where they are on the bed but basically we're just gonna have to work on this in little increments and try to get it as close to zero as possible so i'll continue to work around for a moment and we're getting closer i'm making smaller and smaller adjustments here we're getting all down into the hundreds it does tell you your whole bed variance we're down to a 0.08 i think i can get a little closer so i'm going to still keep working on it i'm just running these adjusting the screws tiny amounts and then running it again i try to adjust them in the same order every time i'm getting really close now i'm down to a 0.033 which is pretty good i don't know if we can actually get closer than that i'm going to work on this red one and these two yellow ones see if i can get them a bit closer and then we'll see what we end up with and i was able to get it down to a 0.013 i've been seeing one nine pretty consistently but i don't think the probe slash bed configuration is accurate enough to get down much lower than that you could mess with this thing all day but this is a pretty small amount of measurement we're talking 1900s here and auto bed leveling can take care of the rest from there i'm sure so i think that's where i'm going to leave it i was able to actually get a few zeros but every time you run it it'll change a bit so let's go ahead and hit finished and let's run our other bed visualizer plug in we'll just update mesh and that is about as flat as i could ever expect a bed to be again you could obsess over this a lot but here was our 60c measurement with the hot end on before and here's the same now so it's a definite improvement and a pretty easy mod to do i want to just run that mesh one more time to see how consistent it is and it looks pretty good it's fairly consistent so overall i'm pretty impressed with this modification it's pretty easy to do and the plugins are really handy and make it really easy to adjust it and it seems to be pretty consistent i ran through this process probably 20 plus times just to make sure everything still stayed the same way and apparently it does it doesn't change much at all so now let's go ahead and run another test print on this setup after the mod just to see if there's any differences in those prints so here's our test prints before and after let's take some measurements on all the corners just to see what they are i'm not expecting to see a lot of difference but we'll see here's the top left on the before print we got a 1.16 top right 1.13 bottom right 1.17 that might have been 1.18 and bottom left 1.15 now let's see if the bed test after the fix is any more consistent top left almost 1.16 top right 1.12 bottom right almost 1.19 bottom left 1.18 so for at least this print this prints only supposed to be about a millimeter tall it really didn't help with consistency any it might over a larger print but this one was pretty inconclusive they really don't look much different either so there it is the nyloc nut bed mod for your prusa printer is now complete and i have to say it was a success my bed is a lot more level now than it was when i started in fact i have a couple of other crucial machines i might have to give this a try on thanks to ben and sergio for showing me how to do this and all the people that worked on this project the write up and the plugin was very well done so hopefully you found this interesting that's it for today and i'll see you very soon on the next one

Channel: Chris Riley

Views: 50,007

Keywords: 3D, printer, Printing, 3D Printing, 3D Printer, ChrisBasement, ChrissBasement, Chris'sBasement, Chris Basement, Chriss Basement, Chris's Basement, ChrisRiley, Chris Riley, benchy, 3dbenchy, 3d, Prusa MK3, Bed Leveling, Prusa Hacks, Prusa, Pinda, ABL

Id: qRbMOfMy-MA

Length: 30min 29sec (1829 seconds)

Published: Wed Jan 20 2021