One of the worst things about most issues related to 3D printing is that they are usually very cryptic, with no real signs to direct us to the proper solution without a lot of time and effort spent on research.
Fortunately, in rare cases, it’s also possible to stumble upon issues that show visible effects on parts of the 3D printer alongside affecting the printed model, making it much easier to identify the problem and apply the appropriate solution.
Today, our topic is one of the issues that fall into the less cryptic side of 3D printing problems, known as filament clumping, where the filament ends up gathering on the tip of the nozzle, dries out, blocks part of the nozzle, and causes the 3D printer to under-extrude as new filament can’t pass through the nozzle correctly.
So, what causes 3D printer filament to clump on the nozzle?
Below, we have listed the most common reasons that can cause 3D printer filament to clump on the nozzle:
- The distance between the nozzle and the build plate is too great.
- The 3D printer nozzle is partially or entirely clogged.
- The print temperature is not high enough.
- The extrusion multiplier is too high.
- The print surface is not clean.
Next up, we will analyze the factors that can cause 3D printer filament to clump on the nozzle in more detail, find out what we can do to fix this problem, and discuss ways to identify this issue as quickly as possible to apply the appropriate fix.
What Causes 3D Printer Filament to Clump on the Nozzle?
As the issue of filament clumping on the nozzle can be a product of a few different problems, we will talk about each of these problems individually in detail throughout this section to make it easier for you to pinpoint the one that’s causing the issue in your case.
Here are the most common factors that can contribute to filament gathering on the nozzle of your 3D printer, creating clumps:
- Large distances between the build plate and the nozzle – A significant distance between the build plate and the nozzle due to a misconfigured Z offset or an unlevel bed will prevent the filament from connecting with the surface. As a result, the filament will gather on the nozzle instead.
- Partially or fully clogged 3D printer nozzle – A clogged 3D printer nozzle will prevent the filament from having enough room to flow out of the nozzle, causing it to get stuck inside the nozzle and clump up.
- Too low print temperature – A too low print temperature will prevent the plastic from reaching the state where it’s fully melted and can flow freely out of the nozzle, which can end up getting stuck on the nozzle and clumping up.
- Too high extrusion multiplier (flow rate) – A too high flow rate value will cause the extruder to extrude more plastic that can fit in the space under the nozzle, which will cause the plastic to gather on the nozzle with nowhere else to go.
- Dirty print surface – A print surface that isn’t clean will reduce its adhesive capabilities, repelling the plastic from sticking to it and making it more likely for the plastic to stick to the nozzle itself instead, causing the clumps.
How to Prevent the Issue of 3D Printer Filament Clumping on the Nozzle?
Since there are a few factors that can cause the issue of filament clumping, taking preventative measures is all about ensuring that there are no issues on any of these fronts by following a checklist.
Below, we have listed the solutions for the most common culprits that can cause the issue of 3D printer filament clumping:
- Clean the nozzle before each printing process, especially if you switch between filaments.
- Clean the build plate before each printing process.
- Ensure that the bed is level before each print.
- Re-configure the Z-offset value.
- Use the print temperature values recommended by the manufacturer.
- Keep the extrusion multiplier at its default value of 100%.
Applying these solutions will allow the filament to have a clear path out of the nozzle and strengthen the chance of the filament coming out of the nozzle connecting with the build plate or the model, which will prevent it from clumping on the nozzle.
How to Fix the Issue of 3D Printer Filament Clumping on the Nozzle?
The course of action to fix the issue of filament clumping on the nozzle is pretty straightforward, which is to clean the nozzle thoroughly and get rid of all the leftover filament blocking the extrusion path.
To clean the nozzle of the clumps that have gathered on it, the first thing we recommend doing is to wipe the nozzle with a wet (water or alcohol will do) cloth or a wet wipe while it’s still warm, which will allow you to get most of the melted filament off.
Afterward, clean the inside of the nozzle with a wire brush to free it of any clumps that are clogging it, creating a clear path for the filament to move through it without problems.
Finally, perform the cold pull process to remove any filament that may have gathered around the interior walls of the nozzle, which will free the nozzle of any leftover filament that may have collected there.
If you cannot get all the filament off with the steps above, using the more complex method of disassembling the nozzle and thoroughly cleaning it should provide a more definitive solution at the expense of spending more time and effort.
How to Identify the Issue of 3D Printer Filament Clumping on the Nozzle?
Since being familiar with the signs that occur due to the clumping of the filament will come in quite handy to identify the problem as soon as possible, let’s quickly go over these signs to make the identification process less challenging.
The primary sign of 3D printer filament clumping on the nozzle is parts of the filament not sticking to the bed or the model and staying on the nozzle instead, causing under-extrusion in some regions.
Aside from the under-extrusion, the filament gathering on the nozzle will eventually connect with the model as it grows large, creating blobs of plastic that should not be there and reducing the surface quality even further.
As it’s possible to observe both of these occurrences by only watching the printing process, you should be able to identify the plastic that clumps on the nozzle of your 3D printer reasonably quickly.
As filament clumping on the nozzle of your 3D printer will drastically reduce the quality of your prints due to the many problems it brings, we highly recommend finding out what’s causing the clumping and cleaning the clumps out of the nozzle as quickly as possible.
To quickly recap, distinct factors such as too much distance between the nozzle and the build plate, a clogged nozzle, a print temperature that is too low, a flow rate value that is too high, and a print surface that isn’t clean can all cause the plastic to clump on your 3D printer’s nozzle.
Essentially, considering that everything that prevents the plastic from making a healthy level of contact with the build plate will cause the plastic to gather on the nozzle due to it not having anywhere else to stick to, it’s a good idea to keep an eye on other factors that you can think of as well.
Mike started his 3D printing journey with the Anet A8 when it first came out back in 2017, and has been obsessed with 3D printers ever since. Nowadays, he primarily uses his Ender 3 to print functional parts that make his life more convenient whenever possible.