PETG Not Sticking to The Print Bed? Try These Solutions!

If you have ever printed with PETG and PLA, then you might know how difficult it is to deal with PETG as compared to PLA. PETG thermoplastic can be abbreviated as Polyethylene Terephthalate modified with Glycol. 

As compared to PLA, PETG has higher viscosity and it is transparent. The printing parameters for PETG are totally different and many times users complain about PETG not sticking to the print bed. 

Often PETG not sticking to the print bed is caused by one of the reasons as below:

• Improper print settings 
• Moisture Filament 
• Low quality filament 
• Dirty, Unclean or incompatible print bed.

In this guide we will get deeply into each of these problems and solutions to it. 

Why To Print With PETG instead of PLA?

Many people opt for PETG instead of easy to use PLA because of the following reasons:

The properties of PETG are different from PLA, especially with Glycol, it undergoes more transformation. Glycol reduces the crystallization and melting temperature of PETG. This helps to get the clean print and the material looks transparent too. Mixing of Glycol reduces the viscosity and helps to print fast and clean. 

Objects printed using PETG are highly suitable for outdoor usage because they are impact resistant and weather resistant. A few of PETG filaments are food safe (not all) and can be used for food processing. While the PLA is opposed to it. 

PETG finds its wide application in medical applications, food containers, decorative products.etc. This plastic is also used in transparent sheathing and canopies.

Printing Parameter Differences

Printing of PETG is easy when compared to other filaments materials, but it needs different settings and configurations. 

• PETG can be printed at fast speed upto 100 millimeter per second 
• It doesnt smell while printing. 
• PETG surfaces can be beautified with Sandpaper as similar to PLA 
• Varnishing and painting is possible for PETG object. PETG can also be dyed.

PETG Print Settings 

Before starting to print with PETG, check if the printer has a preloaded PETG profile in its software. Many printer brands supply their softwares with profiles for all filament types including PETG. If PETG profile is absent, then you may go ahead with PLA profile and tune up the values manually. Give a special focus on parameters that participate in adhesion with print bed.  

• Ensure the Nozzle temperature to 230 Deg C. While printing the Filigree components the first layer temperature should be 235 Deg C. With low quality PETG filaments, this value should start from 235DegC 
• The printing speed for PETG should start from 60 millimeters per second and can go upto 120 millimeters per second. The values vary between different filaments and need to be tried and tested.
• The retraction settings are the same as that of PLA.
• Bed temperature for PETG should be 75-90 DegC. Bare glass can bond the PETG well. Usage of Adhesive tape or glue sticks are not needed.
• When it comes to cooling, PETG undergoes more transformation while getting cooled. Fan speed should be kept minimal during initial 3 layers to maintain the temperature and boost adhesion with the print bed.

PETG Not Sticking to The Print Bed: Problems

Let’s say that you’ve configured all the settings and still filament is coming out of the nozzle and the first layer of the PETG printing is not sticking at all. Initial layers have not attained their minimal shapes instead they are clumping around the nozzle. Below might be the reasons for it. 

1. Temperature is Wrong: 

PETG has a higher melting point than PLA. Always note that PETG requires the higher temperatures both in extruder and also the print bed. 

When PETG doesnt stick to the bed, check for the temperature values. If the values are low, raise the temperature to 210 Deg C to 250 Deg C for the extruder, while keeping it between 80 to 100 DegC for the print bed. 

Many times, results can be obtained even at a temperature of 75 Deg C and other times, temperature needed would be 125DegC. What is the reason for this variation? This is because all PETG filaments are not the same. 

Many users have noticed the differences in quality between various PETG filaments. To speak of, the temperature values vary even with different colors of PETG filament. So, observation is needed to understand suitable temperature values for different print objects. The same logic is applicable even while setting the extruder temperature too. 

So what temperature is right for your object being printed? If you keep too high a temperature, the filament melts more and gets thinner pulling the threads. Whereas if the temperature is too low, then the filament material will get torn and crumble. 

2. Improper Fan Settings

PETG is a high temperature thermoplastic meaning it gets softened and melted when heated. While it contracts when cooling. The speed at which PETG contracts is dependent on the amount of inherent Adhesion. Having said this, one should be careful enough while adjusting the fan speed. If fan speed is not optimized, it gives rise to sticky threads and blobs. This causes the object to not stick to the print bed. 

When it comes to fan settings, the fan should be switched off or lightly running while printing the initial 1 to 2 layers. The reason is the higher the temperature, more the adhesion with the print bed. Thus in order to ensure the object’s adhesion with the print bed, fan should be switched on after initial 2 to 3 layers. 

You can reduce the temperature to a certain extent if the room has circulating air and the fan is switched off. On the other hand, if the material is too cold, then the layers will not stick to each other. Trying with mid-range temperature values is again a question of patience and experiment.  When the corners are unclean, entrained infills result, it’s an indication of low temperature or fan running at high speed.

3. Poor First Layer

In 3d printing, one layer acts as a foundation for another layer. Each and every layer must bond between themselves in order for the object to be created. The first payer specifically defines the success of the whole object. If it’s not optimally printed, the object will not stick to the print bed and falls off, it gets warped and following layers also follow the same. Thus getting a clean first layer is crucial and a proper calibration of the build platform is essential for it.

Opt for automatic calibration to minimize the calibration errors. In addition, the print bed should also be of high quality such as glass surface. I recommend the PEI build plate.

4. Incorrect Printing Speed

This is another important factor that determines the bondage between the object and the print bed. Generally, print speed for PETG varies between 60 millimeters per second to 100 millimeters per second. However, different 3D users use their own print speed values. 

What is the reason? It is because of their experience with PETG. As discussed, the PETG properties will always vary even within a single filament roll. Thus, there are differences because of production, transportation, storage.etc.

Therefore, it is important to adjust the print speed for PETG when you see that the object is not sticking to the print bed. If the print speed is too low or too high, then its possible that the object will not stick to the bed because of it. PETG can also be printed at 40 Millimeter per sec while achieving the highest print quality. Thus, the print speed is not the same for all PETG users and printers. It needs testing and experience.

5. Incorrect Nozzle Spacing

We all know that the bed and Nozzle should be heated to print the PETG filament. Also, when PETG is heated and cooled, it contracts to some extent. The same phenomenon happens even with the Nozzle and the Print Bed. 

When the Nozzle gets heated, its material expands a little bit, reducing its distance between the heat bed. Similarly, when the print bed gets heated, its material also expands and moves much more closer to the Nozzle. Therefore it is advised to set the Nozzle spacing when it is heated. 

There is also another print bed bulging problem that occurs at the midpoint of the print bed. Due to high temperature, the material of the print bed expands and bulges upwards at the center. 

This causes the differential distance between Nozzle and Print bed at the edges and the center. If you measure at the edge, the distance will be normal while if you measure at center, the distance will be very less and Nozzle literally scrapes the object top layers. Now, changing the print bed is not a solution, because it regains its properties once cooled down. Thus, a possible solution is to print the object either at the exclusive center or at the sides. Optionally, you can make use of a glass plate that has less curvature to minimize these problems. 

6. PETG Stringing

Retraction setting is another factor and if it is set too low and slow then thicker  threads will appear from one point to another. It’s not completely possible to avoid stringing with PETG, live with it and adjust to keep them minimal. 

7. Moisture Filament 

When the PETG filament is exposed to free air, it attracts moisture and the print quality is ruined when printed with moisture filament. Hence storing the filament in an airtight container along with silica gel packets should do the trick.

You can also make use of special storage boxes to keep them moisture proof.

8. Poor Quality Filament 

Often, many 3d users are enamored by the low price filaments and they don’t realize the post print circumstances that occur. Don’t get attracted by low price and low quality filaments, go with a quality filament to get quality print output. 

Buy this PETG filament to get great results.

 

9. Unclean Print Bed

When the print bed is dirty, any amount of filament adhesion will not help. Melted filament cant stick to dirty surfaces. So keep it clean. 

10. Try with Different Print Plates

The material used to make each print plate varies and its properties also differ. Some plates may be easy or difficult to handle with PETG. 

There is one PEI sheet that has shown a great adhesion to PETG at a temperature of 100DegC for the first 2 layers. Also for layers from 3 to 5, the temperature should be brought down to 90 DegC. When PETG is pressed on this PEI sheet, it bonds well and the temperature should be brought down further 10 DegC after 5 th layer. Otherwise, it leads to Warping and pulls all the down layers getting separated from the bed. 

Whichever printing plate you use, ensure it is clean and free from grease. Clean the plate with isopropyl alcohol and dont touch with fingers once cleaned.

Use hand gloves to avoid touching the plate. 

11. Use Glass Plate

When using the Glass plate, clean it with simple citric acid at a temperature of 75 Deg C. This improves PETG adhesion to print bed. Ensure that the glass is free of grease and the gap between Nozzle to Bed gap should be very minimal. While printing the first layer, the temperature should be 110DegC and  75 DegC for subsequent layers. This ensures the strong bond with PETG object. In order to remove the print, cold water should be applied before it gets cooled. This detaches the print itself from the print bed.

Conclusion

In conclusion, the reason for PETG not sticking to the print bed has to be tested and experimented. It may be due to temperature values, nozzle distance, filament quality or print bed itself.

However, usage of glue sticks, tapes, sprays are not recommended, instead, play with the settings. 

Also, as we discussed, PETG is sensitive to both high temperatures and low humidity. If it gets cold, it will become brittle. Thus it’s important to properly store the filament in the airtight plastic boxes supplied by the manufacturer. The boxes should also be light proof, meaning light shouldnt penetrate through them. 

PETG is not highly sensitive to UV radiation as much as PLA. If you use the dry beads made up of silica gel, they ensure that the humidity will not increase within the box. 

Last but least, use the quality PETG filament from a reputed brand. THis ensures that the fluctuations are minimal as compared to other cheaper brands.