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Why is my FDM/FFF 3D Printer not extruding?

The basics of FDM 3D printing, is that layers are extruded on top of each other to create a desired shape- however when the layers cannot be extruded, how do we fix the problem? This guide will run through a …

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Tom Watkins

April 24, 2020

The basics of FDM 3D printing, is that layers are extruded on top of each other to create a desired shape- however when the layers cannot be extruded, how do we fix the problem? This guide will run through a few areas, and will explain how we can fix the problem of an FDM printer not extruding.

Where could the issue be occurring from?

One of the best starting points is to think about all the significant sections of the printing process. The image and key below helps to give an understanding of where each issue can build up.

parts of the printing process

A) Slicing software

B) Filament

C) Filament path

D) Extruder

E) Hot End/Heating

F) Nozzle

G) Extruded filament

H) Build platform

As part “G) Extruded filament” is not occurring as our FDM 3D printer is not extruding, we shall remove this from the equation. Working our way through all the other sections will allow us to understand where issues might occur.

Slicing software

The answer to the extrusion issues could be very simple, and not actually an issue with the printer itself. Its always worth checking software for faults before looking into hardware, as it tends to be an easier (and sometimes cleaner!) fix.

The first place to check is what material are you printing with, often each manufacturer will have a material guide online or with the boxed filament. Check inside here for the temperature they recommend setting. If you are using a value outside of their specified range then the filament could be too cold (causing it to get stuck inside the nozzle),or too hot (causing it to burn up and clog the nozzle).

temperature setting inside slicing software

Filament

We just discussed the filament within the slicing software, and how you can ensure that the temperatures are correct. However there is another simple check you can do. If youre finding that your FDM 3D printer isnt extruding, it could be that it doesnt have enough material. The simplest reason, is that its ran out of material, in which case you will need to re-load with a new spool. Another reason, could be that the filament is tangled or has defects.

The best way to check if your filament is the cause of the issue is to unload, and then you can check by hand if there are any tangles. Its then recommend to cut off about 200mm of filament, and cut the end at an angle as shown below. Cutting it an angle will help the filament to feed through the filaments path and out the nozzle.

How to cut filament

Filament Path

The filaments path is a term used to encompass the journey of the filament from the spool to the nozzle. The reason we have used this term as there are different designs on the market and terminology associated depending on how the printer is contructed.

Your printer could have a mixture of guide tubes, bowden tubes, PTFE tubes, and more.

Depending on the printer and material, there is sometimes a greater likelihood of filament snapping and becoming jammed inside the path. If there is a blockage then the filament cannot pass through and your printer will not be able to extrude correctly.

Its worthwhile investing in a small diameter metal rod, as this can be used to gently push through the path (some printers will come with them). Another method is to remove the guide/bowden tubes and visibly inspect the areas for blockages.

bowden tube

Extruder

Although there are different extruder’s on the market the principle is widely the same, they take the filament and push it through at the correct speed- or in this case, our FDM 3D printer is not extruding.

If there is a blockage inside the extruder then it will be unable to move filament through the path. With most printers its very easy to either remove the extruder or inspect inside it. You should then be able to see an arrangement of cogs/gears that are used to grab ahold of the filament and push it through. If there is a build up of filament dust then you will want to remove this, and if possible decrease the pressure of the cogs/gears on the filament, as its grounding it up. If there are any solid pieces of snapped filament remove these also

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Hot end/ Heating

If your hot end is unable to heat the material, then it wont be able to reduce down from 1.75mm/2.85mm to the nozzle size you have (usually 0.4mm). This could be a more complex fault, however there are some simple things that can be checked. Often there is a PTFE tube, or an area where the filament passes to the heater. Its often worthwhile checking this component to ensure that the material can pass successfully into the heater before looking for more complex issues.

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Nozzle

Another area which can cause your FDM 3D Printer to not extrude is the nozzle. We have mentioned throughout this blog post already different areas where the nozzle could be clogged. This could be due to several reasons, however now we are looking to see how we can fix the blocked nozzle.

Two tools that make a massive difference to unclogging a nozzle are as follows

  • wire brush
  • <0.4mm rods (easiest way to source this is to purchase acupuncture needles)

By manually heating the nozzle on your printer, you can then use the wire brush to gently scrape any excess material from the end of your nozzle without causing damage. Once this is clean, gently insert the 0.4mm needle up the nozzle, and this will dislodge the jammed material. By either using a length of filament/thin metal rod/the load function the printer can then extrude fresh filament to push the jam out of the nozzle. Let the printer extrude about 100mm of material to ensure that everything is back to normal functionality before continuing.

CFF Fiber Nozzle Replacement (and How to Correct a Nozzle Jam ...
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Build Platform

Lastly, the issues with your extruding could be down to the build platform being too close to the nozzle. This means that there would not be a large enough gap for the material to be extruded through the nozzle, causing it to clog.

The solution to this is simple, ensure that your nozzle is the correct height from the build platform (which is usually about 100 micron). There are different methods to set the nozzle height which will be printer specific, however in general you will need to use a shim (or a piece of paper as this is 100 microns thick) and use this as a feeler gauge. When you feel slight resistance from the nozzle and the build platform this means that it is set up correctly.

build_plate_leveling_back.jpg
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Final note

There is no better time to own a 3D Printer, being able to continue to manufacture while the country is on lockdown is vital, and a desktop 3D printer is a viable solution.

During these tough times we would love to help your business find ways to save money. To speak to a 3D Printing expert, call us on 01926 333 777 or check out our contact us section

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