Ender3 Pro prints won't adhere to glass plate

1. Check Glass Flatness
This may sound obvious, but a good build plate must be perfectly and completely flat. Make sure your sheet of glass isn’t warped. A straight ruler can help you determine the flatness of your glass. If your build surface is uneven, regions of your print’s first layer won’t stick, likely causing a failed print.

If you discover that your glass plate needs to be replaced, keep in mind that there’s different matters to consider when choosing which glass bed to buy for your Ender 3.

2. Level the Bed
We’ve gone over this earlier, but leveling your Ender’s bed is critical. It doesn’t matter if one side of your part is layering perfectly; if the other side is too far or too close to the build plate, it’ll cause print damage or failure. By adjusting the knobs beneath the build platform, you can make sure that every point on your build plate is the same distance from the nozzle.

3. Clean the Bed
“Cleanliness is next to godliness” is a maxim to follow at the very least for successful 3D printing. Dust, dirt, and oil seem to be attracted to any place they shouldn’t be, including your Ender 3 (Pro)’s build plate. A pro tip for good glass bed adhesion is to regularly clean your glass print bed. If you have a clean rag and some isopropyl alcohol, you’re good to go.

4. Adjust the Z Offset
Z offset has already come up in our general considerations for bed adhesion, but there’s more to be said on the matter.

Obviously, establishing a proper distance between the bed and the nozzle is critical for both adhesion and overall success of your print. If the nozzle is too far away from the bed, the extruded plastic will not be able to stick. If the nozzle is too close to the bed, you may damage your bed or your nozzle as well as ruin your first layer, as the plastic may not have room to flow.

A good rule of thumb is that your nozzle should ever-so-slightly squish the extruded plastic onto the platform without inhibiting flow. Z offset can be adjusted either manually or via slicer or firmware settings.

Of course, it’s generally impossible to get a perfect first layer all of the time, but to lessen the effects of bed leveling and Z offset error, consider printing with a slightly higher layer height than the rest of the model. For example, a 0.3-mm layer height is a good starting place for a printer with a 0.4-mm nozzle.

5. Add an Adhesive
You can try this low tech solution to improve print adhesion (Source: MatterHackers)
Some are team glue stick, and others, team hairspray. Magigoo or similar 3D printing bed adhesives also have their enthusiasts.

We’d say that most of them are better than nothing. A heated glass platform tends to do a fair job of gripping extruding filament, but sharp corners and small features are always prone to warp or pop off completely. Simply apply a light, even layer of your choice adhesive, and prepare to notice a drastic improvement.

6. Adjust Bed Temperature
If the first layer cools too quickly while it’s being printed, it can contract and not stick to the glass build plate. Lucky for you, your Ender 3 or Ender 3 Pro has a wonderful heated bed.

If you’re experiencing some pesky bed adhesion issues, try increasing the bed temperature in 5-degree increments. Increased bed temperature should also help you avoid parts popping off the build plate mid-print. Keep in mind, however, that for PLA, we wouldn’t advise running your bed above 65 °C because this can cause elephant’s foot, a bulging first layer. cookie clicker

Note that your printer’s bed temperature will also depend on whether you’re printing PLA, PETG, or ABS.

Adhesion
As you play with your Ender 3’s slicer settings, you may notice a number of settings under “Build Plate Adhesion” or a similar name. This should be where you’ll be able to add brims and rafts, which create a larger surface area of contact between your print and the build plate. These will naturally increase print time, but they can be very useful, especially when that one pesky model with sharp chamfers just won’t stick.

8. Turn Off the Fan
Another pro tip to improve build plate adhesion is to turn off your print fan during the first layer. This will make sure that your first layer doesn’t cool too quickly and warps. This can be easily done in the advanced settings of your slicer. After the first layer is printed, the successive layers will print best with the fan on again.