Anycubic Kobra 2 Max Bed Leveling/first layer calibration explained

all right so trying to just help anyone else that's having issues with their Cobra Max like I am um I have two things I'm trying to get dialed in one um I've got some y access shift but save that for another time and two is a first layer uh print and um I have two of these printers and both printers um I have not been able to get a very consistent um first print layer this this what you're looking at here is probably the best uh that I've gotten so far and I just wanted to share uh how I got here so um first and foremost when you're building this thing and you're setting it up um you know I it doesn't feel to me and I you know I'm new to this but it doesn't feel to me like it's vital that um everything is like perfectly Plum and square but you want to get it as close as you can so um the key things to look out for I I think and you know I could be wrong is you want the um the Gantry supports here to be square to the bed you want um the print head access to be parallel to the bed and um and then you want everything to um all of the rollers uh to be snug uh but not loose to where you can spin them by hand so check all three rollers on uh the print head uh the Gant Gantry both sides um and then there's six rollers underneath the bed um if those rollers are overtightened uh they can cause too much you know extra stress on the motors if they're too loose then you're going to get slop and you're going to get play and you're never going to get consistent prints um the other thing and probably the most important thing I'm learning here with what I'm doing is um is the print bed itself being level and um when I first got this machine if I took a straight edge and here I'm just using a um you know a ruler that came from a square this is a 16in uh which is you know pretty much perfect for these machines uh but if I sit this on the print bed you can see that it is flat and flush all the way across and the way that I've got this machine set up now whether you go this way this way this way wherever um it is flat and not only is it flat but if I take the print head off and I sit this flat I can lower uh the print head access onto the ruler and it is completely flat all the way across um as it comes down it makes contact it's consistent it's even um so that tells me it's parallel um you know assuming this is you know even all the way across which I think it is so uh if not good enough um you know I think the key here is you don't want gaps that are thicker than a f a single layer of filament if you have a gap that's thicker than a single layer of filament uh that means that um you know it's either going to be too high or too low uh on the first layer and uh these machines are supposed to have automatic bed leveling it does not seem to be capable of solving that problem um I've tried everything to adjust uh the level sensor you know I do automation for a living I understand how Those sensors work um the to either the tolerance is uh not good enough on that sensor or there's something in the software that um isn't making a good enough mesh for the machine to be able to you know compensate for a half a millimeter a millimeter uh or more of variation in bed level so to get the bed flat um what I did is I installed uh silicone spacers in place of the factory spacers so if you look under the print print bed you're going to find these metal spacers and I replaced them with these silicone ones um I don't remember what the brand is but they came from Amazon in a pack of 12 for I think eight bucks so they're a little bit uh shorter than the original spacer which um I can't seem to find any reason why that would be a problem uh if anything you're going to get a couple extra millimeters of um of uh height available to your prints which yay um so the way that those get installed is you take the bed plate off the Pei plate you'll see uh the eight screws here so left right or left right and center and um one thing I'll note is that the spacers uh that serve the center of the print bed that is the spacer for the center um on second a come on this is one of the spacers for the perimeter so the spacers for the center of the print bed are a little bit longer than the perimeter um so what I did is I just put all the silicone spacers in they're all the same height uh which means that these spacers need to be tightened more than these spacers uh to get um you know the same amount of pressure on the plate uh if I had to do it again I would uh Source or maybe even print a spacer that is the height difference between the perimeter and the center and I would put that on the underside of the silicone um furthest away from the bed so the bottom of the silicone spacer not the top uh especially if you 3D print a spacer if you put it on the top that print will be in contact with a hot surface um and I think over time it's going to warp it's going to compress it's going to problems but I think if you put it on the bottom uh it's got enough thermal separation with the silicone that it wouldn't be an issue um so that's probably what I'm going to do is just print uh some simple uh spacers that are whatever that thickness difference between these two are uh to me it looks like it's about a millimeter maybe two so once the silicone spacers are in um what I did with the bed plate off is I 3D printed an adapter for uh really cheap dial indicator uh that I have uh this thing snaps right onto the side let me raise this up I'm just raising this by pulling the belt on top uh so this thing snaps right onto the side of the print head and then what I did is I would lower this down to where the Cal the gauge would spin a couple times just making sure that I've got you know enough depth here that it never um releases contact with the build plate but not so much that it's you know a lot of friction and what have you uh then what I did is I zeroed it just by spinning the spinning the guy here and I moved this thing all along the print bed and I started in the center and I moved the print bed between the two Center screws and I would tighten those screws to where they were firm um but I got consistent pressure from one to the other and then as I got two screws down and you know at this point these two screws were dialed in and firm but I also hand tightened to a what I felt like was a firm enough that it won't back itself out um but not so firm that I'm really trying to warp the bed or anything like that so I tightened all the screws in that fashion um but then once they were all tight I would either you know if I'm if I'm low over here I would back the screw out just the hair uh if I was high I would tighten the screw down a little extra so like if I was moving from here to here and I saw my dial indicator um show me that that area was higher this area then I just tighten that screw down a little bit more um and as you're moving it around that's that's what you're looking for so if I slid it over to here and this was getting raised up then I want to tighten this screw down more um and then vice versa if this was coming down then I want to back this screw screw up so that was the first step for me um was the dial indicator and I got it pretty good it's not perfect as you can see as it moves around um as it moves around there are variations but it seems to be you know about 5 thou difference which um I haven't done the math on that but I think that's less than the thickness of the first layer so I think that's probably got us in the ballpark close enough so once that part's done it's time to put the build plate back on and I've been using this test print which puts a first layer on top of the screw locations with a couple of extra circles in the middle front middle back which just helps you understand where your Peaks and valleys are so with this print um uh I'm doing more fine tun tuning so what I'm doing now is um after I leveled the bed it was okay but still with just adjusting Z height alone I wasn't able to get consistent some of the squares were uh smushing the filament too much they were flattening and they were creating um you know uh pits uh and some of them were too high and so they would look stringy and the lines that were the filler uh they were actually disconnected so if you go to peel the print off you would um you know you would see one second you would see that uh you could actually peel the squares apart um which tells you that it's too high so uh from this point forward what I was doing is printing this um I was um getting to a point where I started to see one square way off from another as soon as I saw that I would stop the print um and I would take the um you know the if it was a low spot and it was already a pretty well tensioned screw I would back it out just a hair uh and if it was a high spot and and it wasn't overly tensioned already and when I say overly tensioned you it it's going to be a feel thing um I would tighten that screw down a little bit more so I was doing my f adjustment here regardless of tools and measurements just based on the quality of the print and um and this is where I'm at so far and I think it's pretty good and and also as the print improves um I've been able to pull this thing off even with a hot bed plate using nothing more than just a little 3D printed scraper which if if you haven't printed any of these yet these things are amazing I these are the bamboo ones on printables uh by the way this if you just search Cobra 2 max um bed on printables you're going to see this print it'll come right up um with instructions that are pretty decent they got me going uh but these things are awesome for being able to get prints off your bed um I would print a whole batch of these things cuz they don't last very long but you know hell yeah and what's great about them too is they don't leave any residue behind cuz you plastical glass whereas when when you're scratching with your fingernails and your hands you're putting oil on the print bed which can affect the um ability for the first layer to stick and and if you don't have it already get yourself a spray bottle and put some 91% alcohol in it and just spray the print bed every single print and give it one wipe down um it's a godsend so that is how I'm dealing with trying to level the print bed um so far it's working great um we'll see if the prints consistently stay good I'm pretty confident at this point though I've got this leveled in enough that I'm going to start getting much higher quality prints out of this machine um I do also have on this particular machine so I have two of these uh this machine is having issues with Y access shifting during prints so um I think I've got uh something somewhere hang tight so you've probably seen prints like this where where the layers are shifted and um yeah so having issues with that with this machine um not having it with my other machine my theory is that it is um something to do with the rear stepper motor um I got a good tip on that though that I think is worth sharing and basically what I did is if I pull the bed all the way forward um or I'm sorry not pull it all the way forward but if I um if I home everything and then use the little menu there to push the bed all the way forward um I drew some lines with some paint markers across the belt uh the pulley and the shaft and this is going to help me know with confidence uh on both sides um is the belt slipping uh because if the belt is slipping then this line at some point will no longer be aligned with that line um or is the pulley shifting and if that's the case then this line will no longer be in alignment with that line um or is the motor having issue and if the motor's having issue I would expect that these lines are always in alignment but that I'm still getting layer shift so that's where you have to either I think dial in your acceleration uh or it just could be potentially a bad stepper motor um I did see here on the Facebook group that um somebody had a stepper motor where he um with with the motor on and and torque applied was able to rotate the shaft um meaning that the shaft uh is no longer connected to the um to the stator inside of the stepper motor uh so if that's the problem it sucks but I have heard nothing but good things about any cubic and their willingness to send parts so um so I'm confident that they'll send me a stepper motor in you know worst case scenario uh I don't believe I haven't looked it up yet I don't believe that stepper motor would be very expensive typically these machines are built with a array of parts that are pretty damn inexpensive it's the only way they're making money selling these things so um hope this helps someone else and if you have any questions um you know feel free to ask um I'll do my best to respond and and help you guys out if I can and um good luck out there

Channel: Mark Foor

Views: 2,030

Keywords:

Id: e9rsYGmJ8oE

Length: 14min 19sec (859 seconds)

Published: Thu Jan 25 2024