i'm tom and today i'm going to show you howto calibrate your printer's extruder. now let me start out with a bit of terminology:there are two parts on your printer that are involved in squeezing out plastic from thenozzle: one is the hotend which heats and melts the plastic, and the other is the extruder,or sometimes called cold end, which pushes the plastic into the hotend. usually, it sitsright on top of the hotend, but it can also
food safe 3d printing filament, be connected to it with a long teflon tubein a so-called bowden setup. so what we're going to calibrate today isthe amount of plastic that the extruder is going to be pushing into the hotend. now,the extruder isn't a smart assembly that would know the exact amount of plastic that it ispushing at any time - basically, the printer's
controller is only telling the motor how manysteps it should move forward and, by default, it can't guess how much plastic it's feedingwith each single step. so the value that tells it that is the steps per millimeter figure,which is stored in the controller's firmware. and that's exactly the value that what we'regoing to figure out. so under- and overextrusion have a coupleof distinct symptoms. if you're under-extruding, as in your printer is laying down too littleplastic, your prints will end up with gaps in the top layers, they won't be watertightand also not as mechanically strong as they could be. also, overhangs won't print well.however, the surface quality on these prints will look pretty much perfect.on the other hand, if you're over-extruding,
so you have too much plastic laid down, yourprints will end up too large, especially holes will be too tight, surfaces will look over-stuffedand the nozzle will probably be digging through the previous layer on the top surfaces ofyour prints - which will look ugly. but, you will be able to print the radest overhangs,i've manage to print a perfect 20 degree one when i was trying things out.but what you really need is a compromise where the amount of plastic laid down is just right,which is what calibrating helps you achieve. now, for the calibration to work you needto check a couple of things first: - you need to make sure that the extruderstepper motor isn't skipping steps. - your hotend should preferably not be clogged.- the tension on the extruder's idler should
be set so that the hobbed bolt doesn't grindthrough the filament - if you set it too loose, it will have too little grip and slide onthe filament, if it is too tight, it will shred through the filament and lose its grip.there's a wide range of tension that works as long as you don't try and print way toofast. also, once you find a tension setting that works, try and set that same tensioneach time you swap filament or open up the idler for some other reason.- and make sure the filament isn't pulling on the extruder. now, if you have "calibrated" your x or ysteps per mm by, like, printing a 10mm cube and adjusting them until the cube was justthe right size, go right ahead and toss those
values- check out the prusa calculator tofigure out a proper set of values and use those. it doesn't make that much of a differencefor the actual calibration process, but using some arbitrary step/mm for x and y makes abig difference to the results you'll be getting. plus, we're doing the calibration in the firstplace so that you won't have to mess with the x and y steps to get good results. so for the actual calibration, we're goingto tell the controller to extrude a certain length of filament and we're then going tocompare that to the length that was actually pushed through the hotend.first, heat up your hotend to the temperature you normally print at. while that is heatingup, mark the filament at a known distance
from a fixed point - i use the top of my extruderbody as a reference. 100mm for the test extrusion is a good value, but because the extrudermight end up pushing too much plastic, marking it at 100mm might have the marking disappearinto the extruder, so i'm going to mark it at 150mm. next, tell the controller to extrude100mm of filament at a speed that is similar to what it does when printing. for 3mm filament,.5 to 1mm per second (30 to 60 per minute) is a good value to start, for 1.75mm filamentuse 1.5 to 3mm/s (90 to 180 per minute). if the host you're using lets you extrude plastic,set the speed and length and use that - if not, use the command line and send g1 (goto a position) e100 (extruder, 100mm) f30 (at 30mm per minute) or f90 after you sendit g92e0 to reset the extruder. after the
extruder finished, well, extruding, measurethe distance to the mark again and subtract that from the original 150mm. this is thelength of filament that your extruder actually pushed through. in my case, that's 150 minus34mm, 116mm. now, to compensate for that 16mm offset, we'regoing to adjust the steps per millimeter value for the extruder. if you don't know the valueyour printer is using at moment, send it a m503 and it will spit out its current settings.to get the new steps per mm, multiply the old steps per mm with 100mm and divide allthat by the actual length it extruded. that is your new steps/mm value for the extruder.to use it, you can either use the m92 command with the e argument and your new step permillimeter figure to temporarily set it and
you can then send a m500 to get marlin toremember the new value you just sent. or you can update your firmware configuration andre-upload the whole thing, which is how i do it. now, you can run the extrusion calibrationtest a second time to check the calibration. however, the goal is not to get the valuecorrect within .1 percent since the extrusion process is fairly tolerant to little errorslike these. however, to really get the amount of plasticcoming out of the nozzle right, there is one more thing that you need to do, and that measuringthe diameter of your filament. now, you'll definitely need to measure each new filamentyou're using and it's also a good idea to
re-check the filament as you're using it up,since especially the cheap filament can have pretty large deviations from the start tothe end of the roll. what's important about measuring the diameteris that you don't just measure one spot. get a couple samples along about a meter of filamentand also make sure to measure around the filament in case it is oval in any way. take the averageof all those measurements and enter that into your slicer. that's it. so now you've got the basic calibration doneand your printer should be really close to extruding the right amount of plastic. youmight need to tweak the extrusion multiplier if you find that your prints are constantlyover-stuffed or on the other hand not watertight
or have gaps even in the top surfaces thatare many layers thick. what i like to do is adjust the extrusion multiplier until thetop surfaces are just filled and then add like another one or two percent, just to makesure my prints are nice and strong. if you find that you have to adjust the multipliermore than about 10 percent, somthing might
have gone wrong during the calibration - justtry it one more time. so that's it for today, i hope you found thisvideo helpful and it ends up improving your print quality. as always, thanks for watchingand please like and subscribe if you enjoy what i'm doing.
