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[Sticky] Ender 3 Extruder Calibration and Flow Calibration

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Extruder calibration

Items needed: Measuring tape, Calipers, Engineer Scale or etc

The extruder, quickly explained, is a spring, a tooth nut, a motor and a tube. The filament enters the frame and gets moved through the tube by a motor with a tooth nut on it. When you calibrate your extruder, what you actually do is check to see if the motor moves the filament 100mm when you tell it to. Spoiler alert: I have never heard of an Ender 3 with a perfectly calibrated extruder right out of the box. If the motor does NOT move the right amount of filament, you get under extrusion or over extrusion. This is where too little or too much plastic is pushed through. Both can cause issues.

Shortly summed up, you take the tube off at the hotend side of the printer by unscrewing your tube fitting. Then you run filament through the tube and cut it right by the fitting. Then you connect your printer and do the following:

1) Connect to the printer with a terminal. This can be Pronterface; Or if you run Octoprint, the Octopi page has a terminal built in

2) Set extruder to relative by entering M83

3) Heat up your hot-end. This is because you can't extrude cold. Set the hot-end to 200 degrees, make sure the tube is pointing away from the hot-end

4) Tell the extruder to extrude 100mm of filament over 100 seconds. You do this by entering G1 E100 F100 in the terminal

5) Measure how much the extruder actually moved out of the tube. Repeat 3 times and find the medium value(for instance if I measure 97, 99 and 98, then I assume 98 because it's the middle value)

6) If you extrude below 100, you are under-extruding. If you extrude over, you are over-extruding. Let's say you get a value of 98, you are under-extruding by 2%. So now you need to find your original ESteps value. Do that by sending M503 in the console. You get a line back that looks something like this: Recv: echo: M92 X80.00 Y80.00 Z400.00 E94.96 The value you look at is M92 E. In this case, mine says E94.96. This means that on 100mm, it takes E100 steps, so 94.96100 steps = 9496 steps in my case.

You now know your steps and how much you are under-extruding. So you just divide steps with percentage you are extruding(ESteps/Extruded amount), in this case 9496/98. This means my new esteps value will be 96.897(96.90 to round up, max 2 decimals). So now I just send M92 E96.90 to my printer and save to EEPROM(M500). If you use stock firmware then you don't have an EEPROM so you have to add the M92 value to Cura startup code

Test that your extruder extrudes exactly 100mm into free air. If not, do it again, you probably measured wrong

You should only need to calibrate your extruder motor once - but if you ever mess with your extruder(like take off the motor, change out the frame, change the nut and so on and so on, you should run a calibration again to make sure it's still calibrated.

Flow rate calibration

Items needed: Digital caliper

Note: If you do not have a digital caliper, you can't really calibrate flow. But fret not! You can get a good result by going back to extruder calibration, but instead of calibrating through free air, you calibrate through the nozzle. But if you do it like that, you have to re-calibrate your extruder every time you use a different filament. So if you have a digital caliper, free air extruder and then flow calibration are the better choices

This is equally as important as Extruder calibration. Quickly summed up, what you do here is calculate a multiplier for the ESteps for your specific filament. Your extruder is calibrated, great! Except it's calibrated into thin air. What do, what do? 9/10 times you won't extrude the right amount after calibrating your extruder. This is because free air has no resistance at all, but your nozzle does. So your extruder will have to put a different amount of work in for different filament types. This is called your flow rate. You need to calibrate your flow rate for every type of material(one for PrimaCreator EasyPrint PLA, another for PrimaCreator EasyPrint PETG, another for Hatchbox PLA, another for Hatchbox PETG and so on and so on). But theoretically you only need to calibrate it once per filament type.

What you do is the following:

1) Load in a 25mm cube in your slicer. You can make one in a program of your choice or you can just find one on Thingiverse

2) Set it to print only ONE WALL - you go to Shell, and where it says number of walls, put 1. Then you set top and bottom layers to 0, infill to 0% and look for a box named "Alternate extra wall" and tick that off. I like to turn on adhesion because keeping a 1-wall print on your bed is not an easy thing. REMEMBER to set your flow rate to 100%, otherwise it will be difficult to calculate later

3) Then you go ahead and print your 25mm cube with only 1 wall. What you're aiming for is to get a wall thickness that is exactly equal to your line width in your slicer. I will use my settings again to demonstrate. I use a 0.4mm nozzle, and my line width is set to 0.4mm. So ideally my 1-wall cube should have walls that are 0.4mm thick. If they are not, this is where you calibrate.

4) Let's say I printed my cube. But my walls came out measuring only 0.37 but I aimed for 0.4. Then you calculate using that. The formula is Expected wall/actual wall=flow. In this case, 0.4/0.37=1.08(108%)

5) Print another 1-wall cube with your new flow(in my case 108% flow) and measure your walls. If your walls don't match your line width then you measured or calculated wrong

The flow is now calibrated, you just add it to your material profile as your new flow rate. Do this for every new type or brand of filament

Note: If you re-calibrate your extruder, you need to re-calibrate flow rate for your materials too. Luckily you should rarely, if ever, have to re-calibrate your extruder so it shouldn't ever be an issue.

!!!!The two above calibrations are IMPORTANT to make as they are essential to getting strong prints with the right amount of material and proper bonding. !!!!

Original Source:

Business IT Solutions -
Plastic Process Engineering

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