PLA filament and glass beds are a match made in heaven. This material type prints best on glass, so what to do when there is no adhesion?
If PLA is not sticking to a glass bed, the most likely culprit is a dirty surface. A worn-out bed might have low adhesion, but you can improve it with painter’s tape or glue stick. Warped or unleveled glass beds could lead to adherence issues, too. If the bed is fine, check the printing parameters.
It goes without saying that PLA not sticking to a glass bed is a problem that primarily affects users of printers with glass beds, such as Ender 3 (Pro/V2) and similar equipment.
If you have such a printer or swapped an original bed for a glass one on any other printer type, read on.
Why Is PLA Not Sticking To Glass Bed?
Generally, PLA won’t stick to glass beds if the surface is dirty or in case of leveling issues.
However, there are many other instances when adhesion might be hindered.
1. Glass Surface Lacks Adhesion
One of the most common issues with glass beds is that they start losing adhesion as they wear out.
Original Creality glass beds have a slightly textured surface that improves adhesion without leaving any marks on the bottom of your print.
Over time, the surface can wear out, especially if you like printing in the same spot over and over again.
You should also know that the build plate only has one textured side, the front one. The back of the plate is smooth, meaning that if you’ve installed it incorrectly, PLA might not stick to it for this reason.
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2. Unleveled Build Plate
A common mistake, especially when printing in batches, is not leveling the bed before each new print. When the build plate is not leveled, the distance between the building surface and the nozzle might vary, altering layer height.
When the nozzle gets too close to the plate, under extrusion might result in poor bed adhesion.
3. Low Build Plate Temperature
Each 3D printing material requires a different temperature for the nozzle and build plate. When the build plate temperature is too low, the extruded material will cool down too fast and won’t stick to the surface.
Calibrating your printer usually solves this issue, but the temperature could also be low due to a malfunction.
4. Clogged Nozzle
You might fail to see how a clogged nozzle can affect adhesion, but the truth is that it can lead to under extrusion.
Once again, the material won’t stick to the build surface because there is too little of it. Hence, it will cool down faster than it can adhere to the build plate.
5. Warped Build Plate
Perhaps you’ve heard of filament curling and warping, but bed warping can also occur. This isn’t an issue that only affects PEI surfaces either.
Glass build plates can warp, especially when damaged or when the heating element warming them up is damaged.
If the heating element doesn’t warm up the plate uniformly, the alternation of hot and cold spots deforms the glass in a phenomenon known as heat travel – basically waves that show where the plate was heated and where it was not.
Warping is usually permanent, but temporary warping can also occur in larger build plates. In Ender 3 printers, however, the bed is relatively small and this damage is usually permanent.
If you’re using a different printer with a larger bed and warping is temporary, you can remediate the problem by calibrating the printing parameters once the build plate is brought to temperature for the material you’re printing with.
6. Too Much Cooling
In 3D printing, one of the most essential parameters to figure out is the amount of cooling your chosen material needs.
PLA doesn’t need too much of it, so if you set the fan too high, it will cool down too fast and it won’t adhere to the print bed.
7. Wet Filament
Another common mistake is printing with filament right out of the storage box. Whether it’s a new or an already used spool, you must dry the filament before printing.
A high moisture content can interfere with adhesion in the first and all subsequent layers. If, by some miracle, the first layer sticks to the bed, you might end up with gaps between layers and other unsightly defects anyway.
8. Dirty Build Plate
PLA adhesion – and the adhesion of any other filament type, as a matter of fact – can also be hindered by a dirty bed surface.
Filament residues from other prints, but also dust particles, that come between the plate and the material can prevent sticking. This won’t improve with adhesion enhancers either, so the only real solution is to clean the surface.
9. Low Printing Temperature
Besides the bed temperature, you should also consider the nozzle temperature when PLA is not sticking to the bed.
The nozzle – or hot end – temperature determines at what temperature the filament is brought before extrusion.
A common mistake among beginners is believing that the nozzle temperature is the same as the melting point. Or, even worse, that it’s the same as the glass transition temperature.
The truth is that the extrusion temperature should be higher than both. Otherwise, the material cools down too fast and doesn’t adhere properly.
10. Wrong Z-Offset
The Z offset in Cura and similar slicers determines the distance between the nozzle and the build plate. By default, this value is the same as the layer height, or around 0.2mm for standard filament.
However, if you’re using fine or draft filament resolutions and forget to adjust the Z offset, the nozzle might be too close to the build plate. This leads to under extrusion and subsequent adhesion issues.
11. Too Fast Print Speed
Printing parameters play a crucial role in the overall printing quality and potential problems. One parameter you don’t want to get wrong is the print speed.
This value determines the speed at which the arm moves during extrusion.
A too slow speed can result in over extrusion and elephant’s foot. A too fast speed doesn’t give the filament enough time to adhere properly to the build plate.
12. Low Flow Rate
Another parameter that can lead to under extrusion is the flow rate. When it is too low, the printer doesn’t extrude sufficient material for the set print speed.
The fix is as easy as it gets – you have to adjust the flow rate to solve the problem.
13. Unstable Room Temperature
If you’re new to 3D printing, something you might not even think of is the room temperature. The truth is that it, too, can affect bed adhesion and the overall quality of your prints.
When the room temperature is too low, the filament might cool down too fast regardless of the printing parameters.
Air currents from open windows or doors can also have a negative impact on adhesion.
This is why you should place the printer in a quiet room, away from doors and windows and, preferably, you should control the room temperature to maintain it constant.
14. Poor Filament Quality
Lastly, something that can make or break the deal is filament quality. You may be tempted to use cheap filament from unknown brands, but you should refrain from it.
Low-quality filament typically means less money upfront, but a lot more in the long run. You can expect to deal with ruined prints, throwing away material, and wasting time and money on everything from filament to energy bills.
This is why it pays to invest in good-quality filament from the start.
How To Improve PLA Adhesion To Glass Bed
Knowing what causes the Creality glass bed not sticking to PLA – or vice versa – is key to finding a solution.
Based on the reasons above, here’s how to fix the issue.
1. Improve Bed Adhesion
It doesn’t take a rocket scientist to figure out that if the glass surface has poor adhesion, the easiest way to fix this is by using adhesion enhancers.
Before using anything, though, you should inspect the plate.
Take it off your Ender 3 printer and look at both sides. The top of the plate must be slightly textured and matt in appearance, while the bottom is usually shiny.
Often, Creality prints its logo in a corner of the plate, which is another telltale of which side goes up.
If you’ve installed the bed on the wrong side, flipping it might solve the problem. Another issue could be that you’re printing in the same spot over and over again, and that portion of plate is worn out.
If you print miniatures or figurines, choosing to print on another area of the build surface could also help you skip adhesion enhancers.
Yet, if the bed is too worn out or PLA doesn’t stick to it for some reason, you can improve adhesion with blue painter’s tape, glue stick, or hairspray.
2. Level The Build Plate
If the build plate is new or you’ve tried enhancers but the print still doesn’t stick, the next thing to do is to level the build plate.
The steps below explain the bed leveling procedure on an Ender 3 printer, but the process is similar on other types:
- On your printer’s LCD, go to the Prepare menu and select Auto Home, then Disable Steppers.
- Turn the leveling wheels on the sides of the bed counterclockwise and lower the build plate as much as possible.
- Locate the bottom left adjustment screw and position the nozzle right above it.
- Place a piece of paper on the bed under the nozzle and adjust the leveling wheel clockwise until there is just enough space to slip the piece of paper between the bed and the nozzle.
- Move the piece of paper and nozzle arm to the next corner and adjust the bed height until you can only slip the piece of paper between the nozzle and the bed. Repeat for each corner.
3. Calibrate Build Plate Temperature
With the bed calibrated, you should now calibrate the build plate temperature. This temperature varies from material to material, but different PLA brands might also have slightly different requirements.
In most cases, you should heat the bed to 60°C to 70°C.
If you don’t have the filament label anymore and can’t find the actual temperature online, start from the lowest temperature and adjust in small increments (5°C) at a time until the material sticks properly.
4. Adjust Nozzle Temperature
As explained, the nozzle temperature is also important.
PLA requires a printing temperature between 190°C and 220°C. This temperature is above PLA’s melting point, which is 170°C to 180°C.
Once again, the actual temperature can vary from brand to brand, and even from printer to printer.
On the Ender 3, the standard temperatures for PLA are 200°C for the nozzle and 60°C for the bed. If you have another printer or these temps don’t work, adjust in small increments at a time until the material sticks.
5. Reduce Fan Speed
Next, consider the fan speed. In Cura, which is one of the most common slicers, the fan speed for PLA is 100% by default. At full cooling speed, the material cools fast enough to ensure sufficient strength and minimal defects.
What the textbook might not say is that leaving the fan on full blast can affect first layer adhesion.
The solution is simpler than you think. Just turn off the fan for the first layers, or reduce its speed to about 50% if you still want some cooling.
6. Reduce Print Speed
Too fast printing is one of the reasons why PLA doesn’t stick to a glass bed.
As a rule of thumb, the best print speed for PLA on the Ender 3 is about 60mm/second. However, the print speed interval goes from 45mm/s to 65mm/s.
If you’ve set the speed at the sweet spot, but adhesion is not great, try to reduce the speed further. Many external factors and even the type of filament can change the standard speed.
7. Adjust Z-Offset
We mentioned the Z-offset, which is the distance between the nozzle and the build plate.
The Z-offset should be the same as the filament width. Hence, for standard-size PLA, it should be 0.2mm.
However, not all PLA spools are standard size. Fine PLA filament is only 0.1mm thick. Leaving the Z-offset at 0.2mm would cause over extrusion and elephant’s foot.
Draft PLA has a thickness of 0.3mm. In this case, the 0.2mm of Z-offset would keep the nozzle too close to the build plate. This would result in too much squishing of the first layer and potentially under extrusion problems.
Check the material before printing and adjust the Z-offset accordingly.
8. Adjust Flow Rate
If you have adherence issues, it could also be due to a too low flow rate. PLA requires a flow rate of 100%.
So, if you’ve used another material before PLA and altered this setting in your printer or slicer, bringing it back to 100% might solve the problem.
9. Keep Build Plate Clean
A dirty build plate can be as detrimental as a damaged one. Cleaning a glass build plate isn’t difficult, but it does require care.
For proper cleaning of a build plate, warm it up to the temperature of the last material you’ve printed. Leave it for 30 to 60 minutes so that filament residues soften up.
Use a scraper to gently remove all filament residues. You should be firm but apply little to no pressure, or you might scratch the glass.
When done, let the plate cool down completely. Remove it and wash it with warm water and dishwashing liquid.
Rinse thoroughly to remove all traces of soap and dry it properly before installing it back. Make sure you’ve placed the right side up and level the bed before printing.
10. Keep Nozzle Clean
Another thing that you should keep clean is the nozzle. For the best results, clean the nozzle promptly after use.
Remove filament residues with a wire brush and wipe the nozzle with a damp cloth. If there are clogs, remove them with a needle or another thin and pointy object.
Alternative cleaning methods include solvents, chemical cleaners, and ultrasonic cleaners. If you decide to use solvents, make sure to use something appropriate for the material you’ve been printing with.
PLA, for instance, doesn’t dissolve in acetone, but becomes rubbery and sticky.
11. Dry Filament Before Use
Wet filament might not stick to the build plate and create a variety of other defects. You can solve this by drying it before use.
The various drying methods include a specific filament dryer (which usually has a default mode for PLA and other common filaments), the kitchen oven, or a food dehydrator.
To dry PLA in the oven or food dehydrator, set the appliance to a temperature between 104°F to 113°F (40°C to 45°C). Let it reach and stabilize the temperature (around 30 minutes), then place the spool in the oven.
Leave it there for four to six hours before printing.
12. Use an Enclosure
As explained, air currents and an inconsistent room temperature can lead to adhesion issues.
If you don’t have a dedicated printing room where to keep the temperature constant between 77°F and 86°F, you should consider investing in an enclosure.
13. Replace Build Plate
Printer bed warping is another cause of poor adhesion. In the Ender 3, warping is generally permanent and the only solution is to replace the build plate.
While there are many alternatives on the market, know that Creality build plates are inexpensive and the best choice to ensure seamless compatibility with your printer.
Tips For Successful Printing With PLA On Glass
PLA may fail to stick on the glass bed even when you’re following all steps above.
These tips might help you solve the problem.
1. Check Glass Flatness
We mentioned warping and how it can affect adhesion. However, you might believe that bed warping is immediately visible.
This might not be the case. In fact, in most instances, you won’t be able to tell that the bed is warped just by looking at it.
To check that the build plate is truly flat, place a ruler on top of it. A laser or traditional level might also help.
2. Add Brims and Rafts
If you’ve ever checked all the settings and menus on your Ender 3, you might have come across a menu called Build Plate Adhesion.
Those settings aren’t there for nothing. They allow you to print brims and rafts which are support structures that increase the contact surface between the model and the build plate.
Using them increases print time, uses more material, and they can be a pain to remove. Yet, they can dramatically improve the quality of your PLA prints.
3. Rough Up the Glass
If you don’t really care about maintaining the build plate smooth for other materials, you can improve PLA adhesion on the glass bed by roughing up the glass.
All you have to do is a light sanding with fine-grit sandpaper – just make sure the sanding is uniform on all bed areas.
There are various reasons why PLA might not stick to a glass bed, but they can usually be solved with proper printer calibration and an adjustment of the build plate.
If you’ve tried everything but the PLA still doesn’t stick, using brims and rafts might help.