Ender 5 Plus Kinematic 3 Point Levelling

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UPDATED DESIGN - 17 January 2022! ---------------------------------------------------- This is my design for a kinematic self levelling bed system for the Ender 5 plus. This design allows you to fully automate the levelling of your bed to a very high precision - meaning you only then ever have to worry about the nozzle offset. The updated design now incorporates an improved kinematic mechanism based on what is known as the "Maxwell principle". It uses the standard Marlin functionality (gcode G34) and independent z stepper levelling to achieve this. In order to use this setup, you will need to perform extensive modifications to your 3d printer. I've tried to detail as much as I can here, but inevitably you will need to work a few things out for yourself. The setup uses the stock Ender 5 plus heated bed, but it needs to be drilled and modified to suit this setup. In my case, I have used a Bigtreetech GTR v1 / M5 board, with a lot of Marlin configuration in order to get it to work. I only describe here the mechanical changes you need to make, and if you are not familiar with getting Marlin to work to a particular configuration, this modification is probably not for you. Whatever board you use will require 2 spare stepper drivers / sockets available - as design uses 3 independently controlled z stepper motors in order to level the bed. In addition, you will require some kind of probe such as a BL touch - as this does not work without it. Requirements: ------------------- 1. Suitable motherboard with 2 x spare stepper slots to give you a total of 3 steppers allocated to z motor control. 2. 3 stepper motors of the same type 3. Stepper motor wiring, 3 separate cables running to independent steppers on your motherboard. Note you cannot use Y splitter cables etc - they have to be separate stepper sockets. 4. Probe such as BLtouch or equivalent. 5. Knowledge of Marlin v2.x, and ability to troubleshoot your configuration to suit this setup. 6. 3 x 12mm threaded balls with M4 threads. 7. 3 x 500mm linear rails, MGN12H carriages 8. 3 x 500mm 8mm diameter lead screws, all of the same type and pitch 9. Lead screw / stepper couplings x 3 10. 3 x brass threaded supports for lead screws 11. 2 x 2010 alloy extrusion cut to size which I used to provide the necessary fixings between the standard Ender 5+ bed, and where I needed the 3 supports to be. 12. Time and patience to put it all together 13. Dowel pins: 6x 20mmx4mm 14. Superglue 15. Various m3/m4 nuts and bolts 16. 3 x 490mm 2020 extrusion 17. Brackets to secure the above extrusion into place. Bed Modification ---------------------- This setup uses 3 points on the bed to create the levelling process (remember that 3 points in mathematics define a plane, and is all you need. More than 3 points creates stress on the bed and promotes warping). In very simple terms - you need one of the threaded balls to be exactly in the following locations: (When viewing the printer from the front) i) Bed front left support. 10mm from the bed front, and 10mm from the left hand side of the bed. ii) Bed rear left support. 10mm from the bed rear, and 10mm from the left hand side of the bed. iii) Bed right hand support. Exactly in the middle of the right hand side of the bed, and 10mm in from the right hand edge. As the above positions will either interfere or come very close to the heating traces on the bed, it is not advisable to drill straight through the bed in these positions. Instead, I used some 2010 alloy extrusion which I cut exactly to the right length to match the left and right side of the bed. I then drilled the bed and extrusion in a location where there were no heating traces. I tapped the alloy extrusion and screwed into it from the top side of the bed to get a nice secure fit - ensuring that the extrusion was perfectly flush with the edge & end of the standard bed. I drilled a nice countersink from the top of the bed to ensure that the countersunk bolts I used were flush and would not interfere with the glass bed when fitted. Once I had sorted out the fitting of the alloy extrusion - I was then able to drill the mounting holes for the 3 threaded balls and bolt these into position. You should be able to see this from the attached photos and youtube clip I have embedded. Z axis setup --------------- You will need to print 2 of the stepper motor supports and 1 of the stepper brackets with a corner on it. The 3 x 490mm 2020 extrusion needs to be placed exactly as follows: 1. Front left: Edge of 2020 extrusion 46mm from inside edge of front left of printer extrusion 2. Rear left: Edge of 2020 extrusion 104mm from inside edge of rear left of printer extrusion 3. Right side: Edge of 2020 extrusion 219mm inside edge of front right of printer extrusion. The above 2020 extrusions should be supported by brackets ensuring they are perfectly square with the frame. Bolt the 500mm linear to each of the 2020 extrusions. I would advise to put the rail so it bolts into the horizontal extrusion forming the printer top rail - this helps to pull everything tight and square. After printing the z motor brackets, assemble these, along with the lead screws and align each stepper motor so it is centred over the linear rail to avoid any binding. Bed supports ----------------- Print the bed supports. Each one is different and needs to be assembled in the correct place. I print these with supports standing upright - as the cutouts for the nuts etc are a critical size. Glue the dowel pins into the relevant slots. There are optional holes for magnets measuring 10mm diameter x 3mm thick. Assemble the brass threaded leadscrew supports using M3 x 16 bolts and M3 half nuts (these are a little tricky to get into the correct position from below). A tip to get the nuts in place is to use a M3 50mm long bolt, and thread the nut so it is "just" on the end of the bolt. Push the bolt down inside the hexagonal hole, and seat the nut. Then unscrew the bolt applying light pressure so the nut stays in place. Then, turn the bolt 180 degrees and push the head of the bolt against the nut, then insert the securing bolt through the brass leadscrew nut and into the m3 nut and secure whilst still applying pressure with the 50mm bolt. Setup ------- If you have done everything correctly - the threaded balls from the bed, should sit perfectly on the 3 supports. You will notice there is an extra hole in the end of each of the bed supports - on my setup, I inserted a brass heatset (m3) insert with a m3 bolt, and use springs between the bed support and the bed to keep everything tight, and connected (so you can't accidentally knock the bed off). You will now need to configure Marlin for the G34 setup, making sure you select the option for the 3 steppers - and ensure you connect the steppers to the motherboard in the right order. Once you have compiled the firmware - you will see an extra menu option to perform Z levelling. It's up to you whether you do this every print (its quite slow using the stock Marlin settings), or as I do - every few prints manually. The youtube video below should hopefully help give an idea on how it works: https://www.youtube.com/watch?v=-I5dzDhDKwg&t=68s You can find a copy of the firmware sourcecode and IDEX documentation I have written here: https://drive.google.com/drive/folders/1p4-6zlIA4cBuUpSgOc0V-NtMvwz24c9N?usp=sharing