Many people are happy with the results they get from their machines, but sometimes things are a little off. An articulated dragon that won’t articulate, castle walls with layer gaps, press fit objects that don’t fit. These are usually extrusion issues where there is either too much or too little filament coming out of the nozzle.
There are actually a number of reasons why prints turn out that way, but in this discussion we are going to talk about stepper motors and what ESteps are, followed by flow rate because these are the most likely causes of your printing issues if you are new to 3D printing.
Esteps:
Extruders have a “stepper” motor attached to them that allow filament to be pushed towards the hotend. The software program called a slicer determines how much needs to be pushed to get the result you are looking for. ESteps are how we measure that amount comoing out ofthe etruder to make sure it is accurate.
Stepper motors move in steps of precise movements. Most 3D printer stepper motors are 1.8 degree motors. That means they take 200 steps to travel 360 degrees. A 0.9 degree motor would need 400 steps, but those are not typically stock on 3D printers. They are an interesting upgrade I will discuss in a future post. For the purpose of this post I will be talking about 1.8 degree motors.
The type of extruder you have can affect how many steps are needed to extrude the requested amount of filament. Bearing and gear extruders such as what are often found on most entry level printers, are usually 93-96 ESteps. Many dual geared extruders are usually around 136-139 ESteps. They require a different number of steps to extrude 100mm of filament because one has more friction from being dual geared so it needs more steps.
To properly do your ESteps, you have to have a connection to a computer or other means of reading a gcode response. I have discussed both in previous posts, so for our purposes today we turn on our printers, plug in the USB connection to your computer and we will be opening up PrintRun (Pronterface). Once open we wil click connect and in the gcode input box type: M503
After clicking send, lines of information will be displayed. You are looking for M92 X??? Y??? Z??? E???, where ? represents the value returned on screen. You want the E value, that is your initial ESteps.
Your next task is to remove the Bowden tube or other connectors at the extruder. We are only measuring the extruder here, which is why we don’t want anything else connected to the extruder. with a Direct Drive setup, the hotend needs to be disconnected, but needs to stay wired so it can be heated. In PrintRun heat up your printer to at least 180 C (It will not extrude if it is not heated), and tell it to extrude some filament. Slice this off cleanly at the exit of the extruder with a razor blade. Extrude 100mm and cut it off the same way.
Now tape the filament that is supposed to be 100mm flat to a surface and measure it using digital calipers. You are going to take your intial ESteps, and this measurement with a calculator to determine your new ESteps. I really like the ESteps calculator found here: https://www.th3dstudio.com/estep-calculator/
Take the “Serial command to change ESteps” and put it into the gcode input box in Pronterface, then click send. After that type M500 in the input box and click send. This saves the value in your printer’s EEPROM. Type M503 and then send to confirm that the M92 values now reflect your new EStep value. Repeat the measurement to confirm that you are now extruding 100mm of filament.
Once you have set your ESteps, you won’t have to measure this again unless you replace the Motor, the Extruder, or Flash your Firmware. In most instances of printers with multiple extruders, they will use the same ESteps value.
My ESteps video on my YouTube Channel can be found here: https://www.youtube.com/watch?v=eTV5KpBCRHI
Flow Rate:
Filament is not dimentionally accurate, and can come “wet” from the manufacturer. As a result to have an accurate extrusion, and to determine if it is wet, you need to print a 40x40x40 flow cube. You can find an example here: https://cults3d.com/en/3d-model/tool/1mm-duvar-ile-kalibrasyon-kupu-40x40x40
You have to print one of these flow cubes with every roll you buy, as even the same color from the same manufacturer can have differences even in the same batch. The flow cube is to compensate for that. As mentioned, the flow cube can also show you if your filament is wet as you will see material defects present from when water escaped as steam. Yes, your filament can come wet from the manufacturer, even inside a vacuum sealed roll. It just happens to be wet before they spool, weigh and seal it.
When printing the 40x40x40 flow cube, you use the following settings: 0% infill, no top layers, 2 line walls, 0.4mm line. Your expected wall thickness is 0.8mm as a result.
Measure the center of each wall, add them up, and divide by 4. This is your average. For this example we will assume it is 0.78mm
Take the expected value (0.8mm) and divide with the average (0.78mm in this example). So 0.8/0.78=1.025. Based on the example average, your extrusion multiplier is 1.02 or 1.03 as the 0.005 is not measured as a value. In Cura, that’s your flow % which is 102% or 103% which again doesn’t count the 0.5%
When you have used the new extrusion multiplier/Flow % in your print settings, print another cube to verify the value if you wish. Either way, using a gold or silver permanent marker, write on the side of the roll which printer you did the measurement on, and the multiplier/% value. Use this measurement each tim you set up your print settings for that printer with this roll of filament. You need a seperate flow cube for each printer you use that roll on.
My Flow Rate Video URL will be included here shortly.
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