D-Bot CoreXY but expanded and improved. 27.5" X 18" print bed

thingiverse

EDIT: 11/28/2022 Fixed a mistake in the length of the crossmembers under the bed. They were too short, which would make the distance between the Z leadscrews too small, and they would hit the edge of the bed making it unbuildable. New lengths are correct. EDIT: 11/9/2022 I finished adding in the cable chain system. This system is an addon to the printer and if you don't want to use it, simply don't print the 2 holders for the cable chain ends. The 2 cable chains I used are these: https://www.amazon.com/dp/B07VSLJLX4 You will need one bracket found here: https://www.amazon.com/dp/B0B5DRM898 You will need to extend all the wires that go to the hot end as they will need to loop through the cable chains. This includes the nozzle heater, X endstop, hot end thermister, cold end fan, and the stepper motor cable. Between the Y direction cable chain and X direction cable chain you will need some slack for the wires to jump from one chain to the other on the left side. I recommend putting them in a nice cable wrap or mesh sleeve to neaten things up. EDIT: 11/6/2022 I found a seller on Aliexpress that does custom heater sizes. They put up a link to the heater I requested. It is 450mm x 700mm, 110V 750W. This matches the dimensions of the 1/4" glass I will be using on the print bed. It leaves room on the sides for access to the leveling screws, and also roughly coincides with the far left and right travel of the nozzle. You can order your own 450x700mm heater here: https://www.aliexpress.us/item/3256804740319784.html?spm=a2g0o.order_list.0.0.21ef1802yE3C22&gatewayAdapt=glo2usa&_randl_shipto=US Once I get the heater and test it I'll update how I like it here. EDIT: I am currently working on installing the new larger print bed and heater. I didn't think to request no 3M adhesive on the heater, which I recommend you do. The side with adhesive is the side facing the glass, which needs to be removable to clean it. So I had to remove all the adhesive which was a lot of messy work. So when you order your heater tell them no adhesive. END EDIT: This needs to be controlled using a DC to AC Solid State Relay (SSR). Because this will be running off AC power from the wall outlet directly, you won't need more than one power supply if you use this. Just get a single supply to power your controller and extruder heater. No need for bed power supplies anymore! The relay I have coming can be found here: https://www.amazon.com/gp/product/B09QSKVXG7/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 You don't actually need the 60A version. I just ordered overkill so I can use it later for something larger if need be since it's only a couple more dollars. The bed heater really only draws about 7 amps. (750W divided by 110V gives you the current of 6.82 amps.) EDIT: 10/25/2022 One major feature of this design is how the belts are adjusted. You need the 2 belts to have perfectly equal tension in order for the X axis to be perpendicular to the frame. This is easily adjusted behind the extruder. The belts are attached in blocks that slide in channels behind the extruder, and the blocks are attached with a long M5 screw and nut. The other ends of the belts attach next to the extruder but don't move on that end. So to adjust the belts, you first attach the belt ends in the front, then the back and when you put the belts in the bocks, do so with very slight tension just when you start the M5 screw. Then as you tighten the screws the belts tighten. This may take a couple tries to get the starting point right, but once you do, your goal is to have the blocks completely inside their channels somewhere when they are fully tightened. You don't need to bottom them out. Just get their final resting spot in a place where they don't stick out. Then you can move the Y axis all the way to the front or back and make sure the X axis is parallel with the frame. If it isn't, adjust the belt tightness until it is. This is a MAJOR flaw in the large TRONXY printers. There is no good method of adjusting the belts on those printers. EDIT: 10/14/2022 I modeled in the filament spool. This makes it easier to understand. I have changed out the Sketchup model screenshot and deleted the old ones since there were a lot of changes since then. I uploaded the new version of the Sketchup model. EDIT:10/9/2022 I improved the mounting brackets for the controller and stepper drivers. The ones in the pictures curled inward over time and allowed the build plate to run into their bottoms. New brackets are more rigid and the bar passes through their center instead of near the top end. I also made a more robust bracket for the Z endstop. It had the same curling problem. This is a side effect of using resin to print thin, non-symmetrical parts. EDIT 8/21/2022 The build plate is 27.5" X 18" but if you use the extruder included in the model, the actual build area is 21" X 18" because the extruder can't reach the back of the build plate, and can't quite reach the front edge by about 1/4" if you put the 3rd Z axis in the front center. You could make the build plate shorter in the Y axis because of this. But having extra gives you room for upgrades and changes later. Or, really, you could just make the frame longer front to back by 6.5" if you want so the extruder can reach the whole build plate. Your choice. Be sure to order the longest belts you can. Here are the belts I used: https://www.amazon.com/gp/product/B07PGHTSLT/ As you can see in the real life photos, I have not put the full sized build plate in my own printer yet. I extended the depth of the frame but have not built the new build plate yet. It's an ongoing project. I want to reiterate, you CAN'T use 6 heaters. You have to use either 4 or 1 big one. Otherwise there's no way to wire the thermistors properly to give 100K ohms resistance. I recommend using 4 heaters and wire the thermistors in series parallel, and evenly spread the heaters out under the 1/4' glass plate. I have yet to find a single heater that's the proper size. What I mean by series parallel is wire the two thermistors on the left in series, and the 2 on the right in series, and then hook the ends together so the pairs are in parallel with each other. This makes the total equivalent resistance equal to if you had just 1 resistor, and gives you the average temperature of all 4 heaters. If the heaters are not perfectly matched, they won't actually be exactly the same temperature. So I recommend buying all 4 heaters together at the same time. This reduces the odds the power they draw varies by much. Of course using one big heater would alleviate this issue, if you can find one that's the proper size. But using 1 heater means you have to power the whole thing with just one power supply as well, which might be a challenge due to the high current draw. You don't really need 3 power supplies. But you do need at least 2. One is 12V for the various heaters, fans, and motor drivers, and one is 24V for the BIGTREETECH Octopus controller. Unless of course you use some other controller that's 12V, like the RUMBA. That's what I used previously, but it doesn't support as many motors. The MK2B heaters themselves are wired in parallel. The reason I have 3 power supplies is 2 heaters are on one 12V supply and relay, and the other 2 are on the other 12V supply and relay. They draw a LOT of current. Each MK2B heater draws about 12A at 12V. So if you wire them all in parallel you need, at minimum, a 48A power supply just for the heaters. It's much cheaper and probably safer to use 2, 30A supplies instead and wire the heaters in pairs. https://www.amazon.com/gp/product/B00D7CWSCG/ DO NOT try to hook the heaters directly to the controller. It can't handle that much current. Instead, use the heater output to switch the solid state relays on and off that the heaters are attached to. You could wire the heaters in series, or series-parallel, but then they will take a very long time to heat up, but it would reduce the current draw considerably. The wires going to the extruder are held in the air above the extruder by 3 strands of copper wire twisted together using a drill, and they slot into the bracket on the front crossbar. This works, but I'd eventually like to route them through cable chains or something. The DOCX files included are copies of the original from the original CoreXY this is a remake of. They will considerably help with assembly, but there are some differences and changes. For example this printer is designed for use with optical endstops not mechanical ones. And the wheeled guide assemblies are completely different. The extruder is also completely different. The wiring is more complex for this printer because of the external stepper drivers and 4 bed heaters. The TB6600 wiring diagram I added shows a different controller and I do not know if the pinout is the same on the Octopus, so I recommend using an ohm meter and checking for continuity from the pins on the stepper socket boards to the output jacks and verifying they are in the same order. The image also shows jumper wires instead of the small boards, but that is useful because it shows you what the board is accomplishing. Whether you use the boards or jumper wires does not matter and would produce the same result. I prefer the boards as the connections are more reliable. The TB6600 controllers can run on any DC voltage from 9-42V DC. I run mine on the 24V supply. This way they also share power and ground with the controller so you don't have any issues with having separate grounds. Here is the fan controller board that fits the box shown in the model. Just remove the plate. You will need to splice a SATA power plug from an old PC power supply to your 12V and ground from your 12V printer power supply. Black will be ground and yellow hooks to 12V. If your plug has red wires, cut them off and don't use them. https://www.amazon.com/icepc-Channels-Cooling-Controller-Interface/dp/B08CXYZLBK The object on the upper rear crossbar is a holder for 1.5" PVC pipe. Print two of them and use 2 90 degree elbows and some pipe and make a spool holder. EDIT 8/11/2022 I previously took this project down, but decided to reupload it with the original text included. I have not pulled each model out and saved it as an STL yet. So I uploaded the complete printer file to be opened in Sketchup. To print the printable parts you will have to export each part as an STL for print. Most of them have built in supports if they need it. Most are now designed to be printed on a resin printer. The model shows 5 Z axis motors. This is to give you the option to either use 4 in the corners of the bed, or 3 where 2 are in the back and one centered on the front. I recommend using the 3 motor method. Easier to level and not put twisting torque on the bed by not having the threads equal. The model shows 6 MK2 bed heaters, but there is no way to correctly wire the thermistors to give an average temp of all heaters since you can't create the same equivalent resistance with 6 resistors as 1 resistor like you can with 4. So the real solution to this is either use 4 heaters wired in series/parallel, or find one large heater instead. I have included a RAR of the Marlin firmware to use. It is driven by the BIGTREETECH Octopus V1.1 found here: https://www.amazon.com/gp/product/B0967G39SJ The NEMA 23 motors for the X and Y axis need to be driven by external TB6600 stepper drivers found here: https://www.amazon.com/gp/product/B01MYMK1G9/ All other motors are NEMA 17 with a gear reduction on them. The Z motors have a 14:1 gear reduction, and the extruder is 5 to 1. To use NEMA23 motors/TB6600 drivers, you need special PCBs for the controller stepper sockets to jump the pins to the side connectors. You can find them here: https://www.pishop.us/product/pololu-socket-to-external-driver-conversion-board/ EDIT 10/24/2021 I updated the design to fit 10mm GT2 belts and NEMA 23 motors on the X and Y axis. You need to use stand alone stepper controllers for these motors. I used these: https://www.amazon.com/gp/product/B01MYMK1G9 You also need to access the Step,Direction,Enable,Ground pins on your X and Y stepper sockets on your printer controller in order to hook it up to these external stepper drivers. These boards simplify this and route those pins to the screw terminals on your board where you used to hook up your X and Y stepper motors. https://www.pishop.us/product/pololu-socket-to-external-driver-conversion-board/ I added the wiring diagram I used to figure out the wiring to the pictures. It's not the exact same parts, but the wiring is the same. You will need some various hardware that wasn't in the original design as well, including: Eccentric spacers: https://www.amazon.com/gp/product/B08FRJSQ3Q?th=1 Gantry plates: https://www.amazon.com/Mworld2-20-80mm-Durable-Universal-Aluminum/dp/B089DHB6T8 32 tooth 10mm bore pulleys for the X and Y motors: https://www.amazon.com/Zyaobei-Timing-Pulley-Timing-6-35mm-Diameter/dp/B08SVZYHDR I use a Rumba 3D printer controller: https://www.amazon.com/RepRapDiscount-Control-Without-Stepper-Drivers/dp/B014S8BXR8 I added my latest firmware as a RAR. I removed all the old STL files. You will have to open the sketchup model named "D-Bot_Sketchup_Model Edited for 10mm Belts.skp" and export the various parts as STL files and print them. I left the previous version of this printer that used all NEMA 17 motors here as a Sketchup model as well, if you don't want to upgrade to 10mm belts and NEMA 23 motors. The reason I did this upgrade is because the printer is so large, 6mm belts would bounce a lot and cause artifacts in prints. 10mm belts are less stretchy and don't do this, so you can both print faster, and put a heavier direct drive extruder on the extruder gantry. -------------------------------------------------------------------------------------------------------------------- EDIT 11/6/2020: I have upgraded a LOT of the parts on this, and don't have the time to save each new part as a single STL and reupload them all, so I uploaded my most current version of the Sketchup model of the entire printer today. I also made the side extrusions longer so the nozzle will be able to reach the back edge of the print bed, so you can actually use all 17"x17" of it. You will have to install Sketchup, then install the STL exporter plugin, and export all the new parts yourself one by one. The newer motion hardware for the 3 axis are MUCH improved. You will need more rollers and screws, so be warned the BOM isn't correct anymore. I mean, it's correct, but you will need additional stuff like rollers, screws, and nuts. EDIT 2/7/2018 Keep in mind that the Bill of Materials and build guide are just copies of the same thing from the original D-bot CoreXY Thing. I didn't edit them or add any additional parts. So keep that in mind when ordering. Especially the V-slot rails. You will need more than the guide says. Probably about half a meter of 20x40 extra should cover it. This is the extruder it's designed to use, but you could use the standard D-bot CoreXY bowden if you wanted to. Just be sure to print the right mounting plate for the X carriage. The holes are different on mine to fit this: https://www.thingiverse.com/thing:760444 EDIT 2/1/2018 Oh. I forgot to mention. For some reason my X axis is reversed and I can't figure out why. So if you use my firmware you will have to mirror all non-symmetrical parts in your slicer. If you solve this let me know how! There will be more information added later, but for now you can use the Sketchup model to figure almost everything out. All V-slot rails are correct length in the model and the ones laid off to the side are the best combination I found for the cuts with as little waste as possible. I think the second rail in the front of the build plate that I added is NOT included in the rails layout off to the side. So make sure you account for that rail when ordering V-slot. Also you will need more rollers and screws etc for the front rail on the bed. I HIGHLY recommend you use the added rail in the front. The bed is VERY heavy so you will need to order Z axis steppers with gear boxes on them. These are the steppers I used. https://www.ebay.com/itm/US-Ship-14-1-Planetary-Gearbox-High-Torque-Nema-17-Stepper-CNC-Robot-3D-Printer/331601658649?epid=10012076645&hash=item4d34ffc319:g:dxgAAOSwDNdVmx48 I have included my Marlin firmware in the files and it should be pre-calibrated. It's set up for dual extruders even though there is only 1 so you will have to put a dummy thermister on extruder 2 pins or edit it to board type 33 and number of extruders 1 in configuration.h. The 4 heated beds are wired in pairs. Put two beds on each power supply in parallel. For the bed temperature thermister you will need to wire 4 of them in series parallel. So put two in series with each other and the other two in series with each other. Then connect the two sets in parallel with each other so the resulting resistance is 100K. Then hook that to the bed temp pins on your Ramps board. If you don't understand this look at this schematic but ignore the values. All 4 would be 100K ohms. https://sub.allaboutcircuits.com/images/00123.png When your Ramps reads the bed temperature it's not really reading each one and making sure they are all the same. it's reading the AVERAGE temperature of all 4. So be warned. If your heaters are not perfectly identical (they won't be) you may have slight variation of temp on your bed. It's pretty close though and the thick 1/4" glass will even out the heat if you let it sit for a bit and warm up. You will need two solid state relays because you will be using two separate power supplies to power the bed heaters in pairs. Wire the inputs of the relays both to the 12V bed terminals on your Ramps together. So it turns both relays on and off at the same time. I'm sure there will be lots of questions but those are the main differences between this and the regular D-bot. It's been quite a while since I built mine and some of the files might be different versions of the same thing. You would really have the best luck if you opened the Sketchup model and just exported all your own STL files as those are probably all the final design. But if you can't do that I THINK the files I uploaded are complete. Message me if you have any questions. If you post a comment I will probably miss it or not see it for a long time, so message me. Or look me up on Facebook. My name is Amadon Faul.