What to do When Your 3D Prints Won’t Stick to the Plate
Curtis Satterfield, Ph.D.
Bed adhesion is a critical component of both FDM and resin printing. When a print doesn’t adhere to the build surface it will cause warping and failed prints. In this article we will examine the causes of and solutions to this problem.
For FDM printers, be sure your bed is level and use a heated bed or a PEI surface to keep your prints from peeling up. For Resin printers, ensure your plate is level and increase your base layer exposure time.
In order to get a good 3D print, you need to have a good foundation. The first layer of your print is the solid foundation that the rest of the print will be built upon. If the foundation isn’t stuck to the bed, the print will fail. There are various reasons why your 3D print won’t stick to your build plate. The good news is that most causes of prints peeling off the bed have simple solutions. In this article we will examine the causes and solutions to prints peeling off your build plate. In addition, check my other guide on how to calibrate your 3D printer for the best performance.
Level Your Bed to Increase Bed Adhesion
The first step to try in resolving bed adhesion issues is to ensure your bed is leveled properly. This goes for both FDM and resin printers. When we talk about leveling the print bed, we don’t mean getting out a bubble level and ensuring the plate is level to the table its sitting on. For FDM printers this means ensuring that the distance from the nozzle to the bed is the same across the entire bed. At printing height, we want to make sure that as the nozzle moves over the build surface it has a uniform distance regardless of where the nozzle is on the bed.
If your printer nozzle is higher in one area on the build plate the plastic will not be pressed down onto the bed as firmly as other areas. This can cause unevenness in the first layer and as the print cools the plastic will curl or warp and peel up from the bed. By leveling the bed, you ensure that wherever the nozzle prints on the build plate it will have uniform thickness and adhesion.
For resin printers, it is important that both the printer itself and the build plate are level. The printer needs to be level to ensure that the resin isn’t sitting higher on one side of the vat. The build plate needs to be level to the LCD screen to ensure a uniform gap between all parts of the plate and the screen. If the plate is higher on one side the resin will be thicker in that area and will not cure at the same exposure settings. This will cause low adhesion and lead to your print peeling off the bed.
Leveling the build plate in a resin printer will set the proper gap between the LCD screen and your build plate. With a leveled bed the printer will have a uniform layer of resin between the build plate and FEP film as the layer is exposed. Having the resin be the same thickness across the entire layer is key to getting good layer and bed adhesion. Most manufacturers recommend using a sheet of paper between the build plate and the LCD screen to level the bed. I have found that putting an empty vat on the printer and leveling with the FEP film works the best.
Each printer model has its own process for leveling a bed so you will need to consult your printer documentation or a tutorial specific to your printer.
Another simple step related to bed leveling is to clean your build plate before each print. I recommend using isopropyl alcohol to clean both FDM and resin build plates. Spray some alcohol on a lint free cloth and wipe down your build plate. Let the plate thoroughly dry and then begin your print. Don’t clean your resin build plate while attached to the printer. You don’t want to get any alcohol into your resin vat!
Optimize Your Build Plate Surfaces
If your build plate is level and clean but you still have problems with bed adhesion the next step is to consider what type of build surface you are using. This step only applies to FDM printers as resin printers all use a metal build plate. Printers can come with a variety of build plate surfaces including metal, PEI, and glass. For non-heated beds, PEI offers great adhesion and adding a PEI sheet should increase your bed adhesion. I’ve been using PRINTinZ build surfaces for years on my unheated printers and they work amazingly well.
If you are unable to get a PEI sheet for your printer you can use painter’s tape. You can buy rolls of tape or purchase a sheet and cut it down to size. If you want a strong bond between your print and the painter’s tape, I have a tip for you. After sticking the painter’s tape to the build plate wipe it down with rubbing alcohol. This removes the wax surface of the tape and the print will stick like cement. The downside to this method is you will destroy the painter’s tape as you take the print off.
If you have a heated bed with a glass surface, you will need to use a glue stick or hair spray on the bed. Use a glue stick sparingly, you do not need a heavy coating on the bed. My personal preference is Aquanet unscented hair spray (Amazon link). Get a lint free cloth or paper towel and spray a small section of it with the hair spray. Then quickly wipe the cloth across your build plate. Wait approximately 20 seconds and repeat the process but wiping in an alternate direction. While the heater is on the print will be stuck to the plate. After cooling down the print will pop right off.
Warm Build Plates = Better Adhesion
The most common issue that causes lack of adhesion in FDM printers is a cold bed. The bed will draw the heat from the plastic causing it to cool rapidly. The rapid cooling will make the plastic warp peeling up from the bed. The best method to deal with this issue is to add a heater to your print bed. A heated build surface will help the extruded plastic retain the heat and cool down much more slowly. The slower cooling speed prevents the plastic from warping allowing it to stick to the bed.
If you don’t have a heated bed or are unable to add a heater to your print bed, there are other options to try. One method is to put your printer in an enclosure. This can be as simple as a cardboard box that is big enough to fit over your printer. By adding an enclosure, you will trap more of the heat from the printer slowing the cooling rate of the plastic. An enclosure will also prevent drafts in the room from blowing on the print and cooling it down too quickly.
You can also pre-heat your bed before you begin printing. Get a microwavable heating pad (Amazon link) and heat it in the microwave. Then lay the heated pad on your print bed for several minutes before starting the print. The higher bed temperature will keep the plastic from cooling too quickly.
Try reducing the cooling speed of the plastic by keeping the print cooling fan turned off until the 3rd layer of your print. The purpose of the cooling fan is to help the melted plastic solidify more quickly. However, using the fan on the first few layers of the print will cause the plastic to cool too rapidly and can lead to print warping.
If you do have a heated bed and are still having issues with adhesion try increasing the extruder and heat bed temperature by 5 degrees for the first layer. The extra heat will help the plastic adhere to the build plate. If your build plate is thin it may warp or bow as the metal expands from the heat. If you see your second layer separating from the first use a constant temperature for your heated bed.
Nozzle Distance and Adhesion
If your FDM printer bed is level and clean check the distance between your nozzle and the build plate. Known as Z-offset, this is the distance between the tip of the nozzle and the build plate when in the home position. Changing your Z-offset will adjust how close to the build plate the nozzle is on the first layer. If the nozzle is too far away from the build plate you will not get good adhesion. Too close to the build plate and you will grind your filament as the extruder can’t push out the filament.
Each printer will have a different method for setting the Z-offset. Be sure to look up a tutorial on your specific printer if you are unsure of how to adjust this setting. You want to ensure that the first layer is uniform and there are no gaps between the print lines.
I recommend printing a small 10 x 10mm square to calibrate your Z-offset. As the print is beginning look at the first layer. If there are gaps between the filament you will need to adjust your Z-offset, so the nozzle is closer to the bed. If you can see the nozzle digging into previous lines you need to move the nozzle further off the bed. After the print is finished look at the bottom. If you can’t make out the distinct lines of the print you will want to move the nozzle further away from the bed.
A properly calibrated Z-offset will provide the best chance at adhesion on the bed. If you set the Z-offset too low, you risk damaging your print bed as the nozzle can drag and dig into the bed. Elephant’s foot is an issue where the first layers are wider than they are meant to be. If the nozzle is too close to the bed it will force more plastic off to the side resulting in elephant’s foot. Prints can also become stuck on the bed and require a lot of force to remove if the Z-offset is too low. Trying to remove a stuck print can result in damage to the print bed or print surface.
First Layer Print Speed and Thickness
Print speed plays a role in the entire FDM printing process and it can greatly affect your first layer. Most slicers can slow down the first layer speed to ensure the print sticks to the bed. Slowing down the print speed means the nozzle will pass more slowly over the plate allowing the plastic better adherence. The faster you print the first layer the less adhesion it will have. While finding a good first layer speed will depend on your printer try 30% speed for the first layer as a starting point. Slowing down your first layer print speed allows the plastic to absorb more heat from the hot end and the print bed will absorb some of the radiant heat from the nozzle as well.
You can also increase the thickness of the first layer to help with adhesion. Your slicer should allow you to increase either the height or the width of your first layer. Increasing the height of the first layer will extrude extra material that can help if your print surface has some unevenness. Try starting with an extra first layer height of 140% and then tweak it from there. Don’t go too crazy with it, adding to much extra height will result in elephant’s foot.
Typically, you can go up to twice as wide as your nozzle side for extra width and one times your nozzle size for extra height. If you increase your print width and height for the first layer be sure to slow your first layer speed down! Over extruding puts stress on the extruder and it may not be able to keep up which will result in lower adhesion.
First (Base) Layer Exposure for Resin Printers
The base layers for a 3D resin print need to be over exposed in order to ensure good adhesion. You want to set your base layer exposure to approximately 10-12 times your layer exposure. Between 60 to 80 seconds is the typical range for base layer exposure. The base layer exposure time is determined by the resin type that you are using be sure to check for the manufacturers recommended exposure times.
You can take some of the guesswork out of this setting by looking for a resin exposure spreadsheet for your printer. There are many community driven online spreadsheets that list layer and bottom exposure times for different resin brands. Most manufacturers will also have a sheet listing exposure times for their resins and printer. For example, here is the official spreadsheet for exposure times on the Elegoo Mars.
FEP Tension and Build Plate Adhesion
If your build plate is clean and level and your exposure times are correct you should check the tension on your FEP film. The FEP film is a non-stick surface that allows the print to release as the build plate rises between layers. As the build plate rises the resin “peels” off the FEP film. If the FEP film isn’t tensioned properly it will stretch too much and the resin won’t be able to peel properly.
To test the tension on your resin you will need to use a tuning app to measure the frequency of your FEP film in hertz.
- Turn your empty resin vat upside down and set it on a stable surface.
- Open your tuning app (guitar tuner aps work fine) and gently pluck the FEP film with your fingernail. Be sure your hands are clean, so you don’t get any dirt or debris on your FEP.
- Measure the frequency of your FEP with the guitar tuning app.
You want the FEP to resonate at around 350 – 450 hertz. If the frequency is too high, then the FEP is too tight. If the FEP is too tight you risk the film tearing and leaking resin.
You should also check your slicer settings to ensure that the bottom lift distance is set correctly. The printer will need 4 to 5mm of lift distance between layers to properly peel the print off the FEP film. Most slicers have this setting correct out of the box, but it never hurts to check your settings.
Working Temperature for Resin Printers
All resins have a recommended working temperature suggested by the manufacturer. If you are attempting to print in a cold environment your resin may be too viscous and won’t allow the print to stick to the bed. Most resins need to be around 70 degrees Fahrenheit or 21 degrees Celsius. Some thicker resins require even higher ambient temperatures to print properly.
If you must use your printer in a cold environment such as a garage or shed in the winter, try keeping the resin bottles inside until you’re ready to print. The resin will retain its ambient temperature for a while and the heat from the machine will keep it from cooling too fast. You can also put a cover over the printer to trap the ambient heat. You can also purchase a small “printer tent” that helps trap the heat of the printer and keeps the resin in a workable temperature.
Sanding Your Resin Printer Bed
Resin sticks best to non-treated aluminum as the surface is porous and has more surface area for the resin to grip. If your build plate has been treated and none of the other tips have solved your problem, try sanding your build plate. Place a piece of 400 grit sandpaper on a table and rub the build plate back and forth on the sandpaper. Do not use a motorized sander as your risk rounding off the corners of the build plate. You want to remove the coating and expose the aluminum underneath. The sanded plate gives the resin more surface area to adhere to during your prints.