Levelling Process – Adjust your bed right
Many printers include an adjustable bed with several screws or knobs that control the position of the bed.
If your printer has an adjustable bed and you’re having trouble getting your first layer to stick to the bed, the first thing you will want to verify is that your printer’s bed is flat and level.
If the bed is not level, one side of your bed may be too close to the nozzle, while the other side is too far away. Achieving a perfect first layer requires a level print bed.
Once your bed has been properly leveled, you still need to make sure that the nozzle is starting at the correct height relative to the build platform.
Your goal is to locate your extruder the perfect distance away from the build plate — not too far and not too close. For good adhesion to the build plate, you want your filament to be slightly squished against the build plate. While you can adjust these settings by modifying the hardware, it is typically much easier (and much more precise!).
As you extrude the first layer of plastic on top of the build platform, you want to make sure that plastic can properly bond to the surface before starting the next layer. If you print the first layer too fast, the plastic may not have time to bond to the build platform.
For this reason, it is typically very useful to print the first layer at a slower speed so that the plastic has time to bond to the bed.
Temperature and cold bed tends the plastic to shrink
Plastic tends to shrink as it cools from a warm temperature to a cool temperature.
To provide a useful example, imagine a 100 mm wide part that is being printed with ABS plastic.
If the extruder was printing this plastic at 230 degrees Celsius, but it was being deposited onto a cold build platform, it is likely that the plastic would quickly cool down after leaving the hot nozzle.
Some printers also include cooling fans that speed up this cooling process when they are being used.
If this ABS part cooled down to a room temperature of 30 C, the 100 mm wide part would shrink by almost 1.5 mm! Unfortunately, the build platform on your printer is not going to shrink this much, since it is typically kept at a fairly constant temperature.
Because of this fact, the plastic will tend to separate from the build platform as it cools.
This is an important fact to keep in mind as you print your first layer. If you notice that the layer seems to stick initially, but later separates from the print bed as it cools, it is possible that your temperature and cooling settings are to blame.
Many printers that are intended to print high-temperature materials like ABS include a heated bed to help combat these problems. If the bed it heated to maintain a temperature of 110 C for the entire print, it will keep the first layer warm so that it does not shrink. So if your printer has a heated bed, you may want to try heating the bed to prevent the first layer from cooling. As a general starting point, PLA tends to adhere well to a bed that is heated to 60-70 C, while ABS generally works better if the bed is heated to 100-120 C.
Cooling fan – Adjust your cooling fan
If your printer has a cooling fan, you may also want to try disabling that cooling fan for the first few layers of your printer so that the initial layers do not cool down too quickly.
For example, you may want the first layer to start with the fan disabled and then turn on the fan to full power once you reach the 5th layer. In that case, you will need to add two setpoints into that list: Layer 1 at 0% fan speed, and Layer 5 at 100% fan speed. If you are using ABS plastic, it is common to disable the cooling fan for the entire print, so entering a single setpoint would suffice (Layer 1 at 0% fan speed).
If you are working in a breezy environment, you may also want to try to insulate your printer to keep the wind away from your part.
Different plastics tend to adhere better to different materials. For this reason, many printers include a special build platform material that is optimized for their materials. For example, several printers use a BuildTak sheet on the top of their bed that tends to stick very well to PLA. Other manufacturers opt for a heat treated glass bed such as Borosilicate glass, which tends to work very well for ABS when heated. If you are going to print directly onto these surfaces, it is always a good idea to make sure that your build platform is free of dust, grease, or oils before starting the print. Cleaning your print bed with some water or isopropyl rubbing alcohol can make a big difference.
Surface materials to stick better
If your printer does not include a special build platform material to help with adhesion, you still have options! Thankfully, there are several types of tape that stick well to common 3D printing materials. Strips of tape can be applied to the build platform surface and easily removed or replaced if you want to print with a different material.
For example, PLA tends to stick well to blue painter’s tape while ABS tends to stick better to Kapton tape (otherwise known as Polyimide film). Many users have also had great success using a temporary glue or spray on the top of their build platforms. Hair spray, glue sticks, and other sticky substances tend to work very well if everything else has failed. Feel free to experiment to see what works best for you!
Sometimes you are printing a very small part that simply does not have enough surface area to stick to the build platform surface. Several options that can help increase this surface area to provide a larger surface to stick to the print bed are available in the printers software.
One of these options is called a “ brim”. The brim adds extra rings around the exterior of your part, similar to how a brim of a hat increases the circumference of the hat.