CoreXY explained: Comparison + strengths & weaknesses

have you been wondering about core XY printers in this video we'll look at what they are their strengths and their weaknesses [Music] [Music] Couric's wife 3d printers seem to be all of the rage lately this here is a second SK go which I recently did an assembly video on and in the last week I've assembled this trunk cx-5 s a pro other recent printers are the two tree sapphire and Peru so recently announced that they were working on a large format core XY 3d printer the design for a core XY motion system has been around since 2012 but all of a sudden the design seems to be gaining a lot more momentum so in this video we're going to look at exactly what it is and look at the strengths as well as the weaknesses to see if it's ideal for your next 3d printer 3d printers have firmware on a mainboard which is used to control stepper motors and create the motion that makes 3d printing possible the vast majority of 3d printers use a frame and belts with a Cartesian motion system with this design the XY and z axes are all linear but moved together to create 3d toolpaths these days the most popular cartesian motion systems are called a3 style as popularized by the Purusha i three this motion system has humble beginnings dating back to the Purusha Mendel so let's demonstrate it on the hugely popular end of three the end of three has a stepper motor for the x-axis and that controls a gantry that moves from side to side there's one at the rear that moves the bed back and forth for the y-axis and then another one at the rear that moves the z-axis up and down and as you can see it takes the x-axis for the ride along with it this setup is really tried and true and very popular with new 3d printers and the results you can't deny can be simply outstanding even so there are some inherent weaknesses the main one is that the y-axis stepper motor has to move that heavy bed and this problem is exacerbated the larger the printer gets and furthermore the larger heavier and taller the printed object is the greater the inertia the y-axis has to carry which can present itself as surface artifacts most commonly you'll see this in the form of ghosting or ringing the x-axis on this print is pretty clean but when we rotate to the Y we can see that the outline of the Y is repeated on the surface of the print the other problem with these moving bed printers is they're not very efficient for the space they take up when we take the bed through its full range of motion we can see that it overhangs and the front and the rear quite substantially this see our 10 max has a wire length of 450 millimeters but needs just about a meter of space in total to fit it on the bench so what about another Cartesian motion system that doesn't have a moving bed on the y axis one popular design is the ultime Kerr but what I have on hand is as all tracks m200 on this printer the bed still moves but only up and down to create the movement for the z-axis if we inspect the top of the printer we can see that the printhead moves in X as well as the Y and there's a stepper motor assigned to each a printer commonly mislabeled as core XY is the Cree ality and a5 like the salt racks the z-axis controls the bed moving up and down and similarly the x axis moves with its own stepper and the y axis moves independently with its own stepper as well the fact that the x and y axis move independently is a great way to test whether you've got the core XY printer or a regular Cartesian let's have a quick look at the kinematics which for us is when the firmware is calculating movement Cartesian movement is relatively simple to calculate let's have the example of moving 100 millimetres on the x-axis the firmware knows that there might be 80 steps per millimeter for that axis so the calculation is simply 80 times 100 or 8,000 steps for that movement we're ignoring a bunch of things such as acceleration but all things being equal it's easier to crunch the numbers for Cartesian even a diagonal movement is just a calculation each PHA x and y in the vast majority of cases a Cartesian motion system really does get the job done in 3d printing but let's look at some alternatives starting with the Delta Delta 3d printers are completely different when it comes to the motion system they still have three stepper motors as can be seen in the bottom of this monoprice mini Delta but each one controls linear motion up and down a tower if haven't seen one print before it really is amazing the carriages on each corner moving up and down sending the printhead to the right location as if almost by magic even simple straight lines on a delta are a combination of all three towers moving up and down and because of this the kinematics are a lot harder to calculate for the firm where Delta's require a light printhead and because of this almost exclusively Boden ship setups they're well known for both speed as well as high quality but that's more to it than that which we'll illustrate with an analogy in a Cartesian printer the three stepper motors are all doing their own thing even on a diagonal move x and y are moving but they're doing so independently on a delta printer the three stepper motors are actually working together any single move has three stepper motors powering it and that combined with the light head means we can maintain great precision as well as speed there are downsides of course and for some people the circular rather than rectangular bed won't be practical for the types of items that they like to print another weakness of the Delta motion system is the inefficiency for height my students and I built this monstrous k2 80 which has a build height of 600 millimeters but the printer itself is roughly double that not a great use of space but it's bear to say because the footprint is still small it's easier to store than other designs now we'll get on to the main topic core X why I believe this website may be the origin of the system with testing going back to early 2011 and the first design on Thingiverse referencing this page coming in 2012 being a verse also has a very popular hypercube designed in 2016 by fellow Aussie tech to see I'm going to make the argument that core XY 3d printers are a mix between Cartesian and Delta in their characteristics let me explain why firstly they're like a Cartesian in their appearance and they have a single stepper motor to control the z-axis moving up and down secondly like a Cartesian the x and y movement is isolated from the Zed in this case taking place on top of the machine but here's where it starts to differ remember on the end of five that the X&Y stepper motors were tied exclusively to each axis which move independently on a Couric's Y it might seem too much depending on which belt you pull but if you pull another belt something strange starts to happen despite pulling a vertical belt the printhead moves in a 45 degree direction if we move the opposite belt the printhead moves in a 45 degree direction but this time rotated 90 degrees to move anything other than a perfect 45 degree angle both stepper motors need to work together to move around the printhead on our Delta printer we had three stepper motors working together to move the printhead on a core XY we have two stepper motors and it kind of works like a tug-of-war on either side of the printhead the third step are for the z-axis is still doing its own thing independently in the background the core XY website does a reasonable job of introducing the kinematics for such a machine it starts by comparing it to the mechanism on a drawing desk to keep the straight edge horizontal you might have guessed that with two stepper motors being required for any movement calculation of the kinematics is harder to crunch for the firmware and like the Delta printer this type of printers benefit most from a 32-bit mainboard if you want to learn in more detail about core XY kinematics I've linked to a really clever videos in the description one that uses pieces of paper to demonstrate the principles and another that goes through the maths both by CRT on the vector 3d channel like a delta ik or XY is optimal when it has minimal mass to move around you can see for the y-axis we have the print head and a single skinny rod and for the x axis we only have the print head because the print head is not suspended in midair like a delta it is possible to have a pancake stepper direct driven extruder this second SK go also came with the parts to run a lightweight Bowden tube setup if that's what you prefer as part of the preparation for this video I asked the two manufacturers of the parenthesis who are in the intro why they chose a core XY motion system you can pause the video and read their exact responses if you like but they both talked about being lightweight fast and precise with their print heads as well it's very efficient for space when you compare the build volume to the overall size of the printer they both also described the robust motion that comes from two steppers rather than one pulling on the printhead for the majority of moves ernest from second also hints about future compatibility with tool changing systems let's keep our fingers crossed for that one so core XY is the best thing well like everything in engineering there are compromises in a core XY not only other belt systems relatively complicated but they're also very long if you follow each one you'll say it takes quite an interesting path around the printer and back to the other side of the printhead any 3d printer needs properly tensioned belts to print with good performance not doing so introduces some pretty prominent artifacts on a core XY the belts are quite long and therefore can be more difficult to tension if we scale up health ready print is designed by a factor of two the belts become particularly long our first must for core XY is an easy-to-use and reliable belt tensioning system on a large format core XY machine we might ever need to upgrade the belts to be wider or stiffer to cope with this added tension core ex-wife 3d printer frames therefore need to be quite rigid to hold the belt police in place this SK Go has all-metal junctions for the moving parts and the motion system is based on linear rails as well although a different approach the motion system on the trunk C seems to be suitably robust as well another key consideration other belt idlers that need to be suitably stiff to not bend under the pressure of the very tense belts once again as the printer size goes up this becomes even more important getting these things right requires a good engineer and potentially cost in components but if you can get it right the potential is therefore simply outstanding prints the bench II as well as this mask were printed on the SK go at 0.2 millimeter layer height they're both almost completely free of print artifacts a quick note on the h bot which is similar to a core XY but typically has a single belt the page you're seeing here is from a book by Neil Rosenberg called designing 3d printers essential knowledge he was kind enough to send me one it's an excellent reference and it's linked in the description I'm happy to admit that I've used three core XY machines but never an h-pipe so linked in the description is an interesting debate between people who decide debating their merits and which one might be better one other 3d printer motion system that I haven't discovered in this video Escarra or basically a robot arm I'm sure you'll agree the footage you're seeing here is incredibly cool it's linked in the description and time will tell if this format takes off and becomes viable for more 3d printers I hope that was helpful and can show you that core XY is like anything else in engineering there are compromises and it's not automatically the best solution so therefore you need to make an informed decision - what if it's best for you I'm looking forward to finishing testing both of these and potentially doing a shootout and whichever comes out on top is not really important what I think is good is that manufacturers are no longer having a race to the bottom they're looking at other options trying to innovate and that's great to have that choice but consumers if you've already got the core ex-wife 3d printer or you're thinking about getting one feel free to leave your thoughts below in the comments thank you so much for watching and until next time happy 3d printing g'day it's Michael again if you liked the video then please click like if you want to see more content like this in future click Subscribe and make sure you click on the bell to receive every notification if you really want to support the channel and see exclusive content become a patron visit my patreon page see you next time

Channel: Teaching Tech

Views: 329,467

Rating: 4.921814 out of 5

Keywords: 3d printing, 3d printer, 3d print, 3d printed, corexy, core xy, explained, explanation, comparison, compared, cartesian, delta, hbot, h-bot, h bot, kinematics, motion system, stepper motors, mainboard, speed, quality, precision, bowden, direct drive, seckit, seckit3dp, sk-go, tronxy, x5sa-pro, two trees saphire, prusa, hypercube, ender 3, ender 5, creality, cr-10s pro, cr10s pro, cr10, i3 mk3, belt, belt tension, scara, linear rails

Id: _ramiM3KHYE

Length: 12min 32sec (752 seconds)

Published: Fri Nov 08 2019