What Causes Over Extrusion in 3D Printing? How to Fix It?

3D printing is a technology of conveniences, but it is not without jams, glitches, and hitches. It can be annoying when they happen. They are not only a setback on your schedule, but can also lead to wastage of materials and power. Over extrusion is one such problem. You cannot create masterpiece 3D prints when your printer is hemorrhaging out materials with little care for your blueprints. Usually what you get is a model with geometrical/dimensional defects, falling parts, and weak structural bonds. This post outlines the causes and remedies for this problem so you can get beautiful 3D prints.

What is Over Extrusion?

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3D Printing Over Extrusion (source)

Over extrusion is a situation where the 3D printer splotches out too much material. It usually ends up ruining the design quality of your prints. Without solving this problem, your projects will be susceptible to dimensional inaccuracy, oozing blobs, layer drooping and stringing. If you see these signs in your final prints, it would mean that you need to take measures to stop over extrusion.

The glitch is common in all filament and printer brands. The problem is more pronounced when you are attempting to stick two parts of a model. With an over extruded top layer, the result will be an uneven surface that prevents perfect connection between the two pieces.

What Causes Over Extrusion?

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Causes of Over Extrusion in 3D Printing (source)

Extrusion multiplier setting is off

The Extrusion Multiplier controls the extrusion flow rate which refers to the amount of filament coming out of the nozzle. You can usually tell when your extrusion multiplier is off when you see signs such as large layers and frequent nozzle jams. This setting needs reduction.

You can control over extrusion by adjusting either the Extrusion Multiplier settings in the 3D printer Slicer or the Flow rate settings in the 3D printer firmware. These values are always filament specific.

Too high print temperature

When the print temperature is too high, more filament is melted and at a faster rate. The consequence is obvious: the over-melted thread flows uncontrollably out of your printer’s nozzle, interfering with the design quality of your final print.

The hotter the filament gets, the more material it blobs out. Printing at a lower temperature can help to control the amount of the print material to form precise layers with accurate contours. However, it would be best if you didn’t get the temperature too low. That would lead to under extrusion which results in 3D layers not sticking. If the extruder temperature gets too cold, the melted thermoplastics coming out of the nozzle will not be hot enough to bond with the previous layer.

Flow rate set too high

If there is too much filament flowing out of the nozzle, it is highly likely that that problem is your flow rate settings. A high flow rate can destroy the dimensional preciseness of your prints. The upper layers will have larger dimensions than the bottom layers.

A high flow rate allows for the more heated filament to flow out of the nozzle. Even though this can lead to strong bonds between layers, too much of it is destructive. Dial it down a bit to stabilize the level of extrusion.

Incorrect filament diameter

If your slicer gets the wrong filament diameter measurement, the printer will extrude the material at a higher rate leading to over extrusion. The standard filament diameters are 1.75, 2.85, and 3 mm. A correct input of these can help solve the over extrusion problem.

Big nozzle size

Even though nozzle size is often an overlooked detail, it also plays a part in the overall design quality of your final prints. A wrong nozzle side could hold you from your perfect 3D aspirations. It is imperative that when you are shopping for nozzles, find the right nozzle size to achieve a higher resolution in 3D printing.
The nozzle size affects the printer extrusion width of your print. If that is coupled with a higher print speed, you can have a severe case of over extrusion. If you desire to get finely sculpted 3D prints, you might want to ensure that you use a nozzle that lays down the right amount of materials.

How to Fix 3D Printing Over Extrusion?

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Fix 3D Printing Over Extrusion (source)

Reset extrusion multiplier

In the Slicer software, go to the Filament Settings and find Extrusion Multiplier. The default setting is 1 but you can adjust it between 0.9 and 1.1 depending on the filament type you are using. Changing this setting is as simple as rewriting the value. Go to the printer menu when printing and find the Tune settings. The value ranges between 90 and 100, but you can also adjust this slightly upwards or downwards.

When calibrating the Extrusion Multiplier, you can use tools such as calipers or work by observing the visual features of your final print models. Both methods will give you perfect results and help you prevent over extrusion

You will want to decrease this setting by intervals of 2.5% increments as you observe changes in the final print. Take care not to make drastic changes. If you reduce this setting by a big value, you can end up causing under extrusion.

Lower the printing temperature

The obvious step towards preventing over extrusion should be slightly decreasing your printer’s extruder temperature. That, in turn, helps to control the amount of filament passing through the nozzle, since the material gets melted a little slower.

Begin dialing down the temperature when you notice signs of over-extrusion in the prints. To decrease the print temperature, navigate to the Temperature tab in the Edit Process settings. Reduce the values by intervals of 5 degrees as you monitor the changes on the final print.

The process of decreasing the extruder temperature should be done in a gradual process. From the average temperature, start reducing it at intervals of 5 °C until you notice changes in the extrusion levels. Because each filament has its ideal temperature, this process is a trial and see’ as you monitor changes on the final print. If over-extrusion persists then the print temperature is not the cause.

Reduce the flow rate

It’s a trial and error process. You will need to find the best flow rate for each type of new filament roll and set in your machine or slicer. This process generally involves picking a model and trying to print it using different flow rates until you find the best results.

The process should be stepwise, decreasing the rate at intervals of 5%. For instance, if you started with a flow rate of 105% and still notice over extrusion then choose a flow rate of 100%. Continue that way until you find the ideal setting with superb print quality. In case you notice under extrusion, adjust the flow rate upwards a little as appropriate.

Set the right filament diameter in your slicer software

Use a caliper to measure the width of the filament in different places and input the average. Most filament manufacturers will list their dimensional measurements, but it is ideal to get a real value. Small differences might seem insignificant, but in a practical sense, they are the thin line between print perfection and imperfection.

Start by cutting off a few feet of the filament, say 60 cm. During this process ensure the length does not get tangled. Next, make marks on the cut off piece at intervals of 2 cm. Those are about 30 marks. For a white filament use a black marker and light markers for darker threads to keep your measurements easily visible.

Measure the marks using a pair of digital calipers as you write down the measurements. Rotate the calipers around the filament to get accurate measurements. Add up the score and calculate the mean by dividing the total value by 30. The number you get, feed it into the slicer software. Open the software and navigate to Machine Settings and adjust the filament diameter settings accordingly.

Get the right nozzle size

The beauty of 3D printing is that the nozzles are easily interchangeable; you only have to arm yourself with a screwdriver. Nozzle packs are also cheaply available.
The standard nozzle sizes are 0.4mm. They are very common because they are ideal for all type of projects. You can print to layer heights of 0.1mm, or up to 0.3mm using a thin nozzle. Thin layer heights are finely detailed while thick layer heights are flat.

If you are not getting the best results with your 0.4 mm nozzle, you can get a small3D printing nozzle to help you bring out the intricate details of your design without over extrusion.
With some printers, you can use the 0.2mm and 0.15mm nozzles for design precision. Manufacturers are also testing thinner nozzles of 0.1mm diameter. You can expect incredible results with such nozzles.

A 0.2mm nozzle does not extrude the same amount of filament that a 0.4mm nozzle does. The extrusion will be 25% of the filament in this nozzle as compared with a standard 0.4mm. You will use fewer filaments, but the printing will take much time.

If too much material is extruded, you could end up using more filament than is required. When printing models with intricate and detailed geometrical designs, a case of over extrusion can be a big nightmare.

Use the above guide to help you solve the over extrusion menace.

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