What To Do When a 3D Resin Printer Build Plate Isn’t Flat

A 3D resin printer build plate must be flat and leveled for perfect first layer adhesion and flawless prints. However, flat and leveled are not the same thing. You need to check if your 3D SLA, LCD, or DLP printer build plate is flat and leveled and accordingly remedy the problem. 

When a 3D printer build plate isn’t flat, fix it by cleaning with isopropyl alcohol and a lint-free cloth and sand if necessary. Then use a straightedge to test if the entire surface is even. Level the 3D printer build plate using the paper method and adjust the screws as necessary.

Most 3D resin printers function similarly, with slight differences in the designs, parts, and settings. This guide explains the practical ways to ensure your 3D printer build plate is flat and level, irrespective of the manufacturer and model.  

How To Make a 3D Printer Build Plate Flat

Your 3D resin printer build plate may have an uneven surface with scratches and thus high and low points after prolonged use. Hence, you may have adhesion issues even if the plate is aligned and leveled accurately with the resin tank and its film. 

Here are the steps to make a 3D printer build plate flat:

1. Wear a mask, nitrile gloves, and protective eyewear.
2. Remove the build plate from its clamp on the printer.
3. Pour a bit of isopropyl alcohol on a clean, lint-free cloth.
4. Wipe the build plate to clean residual traces of resin.
5. Check for scratches and uneven points on the surface.
6. Use 150 or 120 grit sandpaper to smooth the build plate surface.
7. Sand in all directions for a thorough and uniform smoothening effect. 
8. Clean the surface to wipe off any dust on the 3D printer build plate.
9. Use the lint-free cloth to wipe the surface with isopropyl alcohol.
10. Use 80 or 100 grit sandpaper to create texture on the build plate.
11. Sand in all directions to avoid new high and low points or unevenness. 
12. Use 150 or 200 grit sandpaper to smooth any unintended roughness.
13. Wipe off any dust from the surface and clean it with isopropyl alcohol.
14. Use a straightedge to test if the build plate is flat throughout its surface. 
15. Reinstall the 3D printer build plate and ensure it’s leveled. 

It should be noted that sanding (steps 6-13) is optional for 3D printer build plates with excessive scratches and extensive unevenness. Notably, new build plates shouldn’t require sanding. Thus, if you have received a 3D printer build plate that isn’t perfectly flat, contact the manufacturer to get a replacement. 

It’s important to distinguish the flatness of a 3D printer build plate from its leveling or alignment parallel to the resin tank. If you have a substantially uneven surface, re-leveling the build plate may not solve your first layer adhesion, resin curing, and other problems, including failed prints. 

You may watch this video before sanding your 3D printer build plate:

Pro Tip: Use a heat gun to remove any cured resin stuck on the build plate that is too tough for isopropyl alcohol to wipe off. 

How To Level a 3D Printer Build Plate

Unlike the flatness issue, leveling a 3D printer build plate is essentially a recalibration process. You have to realign the build plate by adjusting the screws so that its entire surface is perfectly parallel to the FEP film or silicone base of the resin tank. 

Many hobbyists like to level their build plate on the 3D printer clamp along the z-axis. And there is more than one recalibration process. However, I explain only the paper method in this guide, as it’s straightforward and effective. 

Here are the steps to level a 3D printer build plate:

1. Place a piece of paper larger than the build plate’s surface on the printer’s platform.
2. Check your 3D printer’s settings or tools and select the ‘home’ option to lower the plate.
3. Hold the piece of paper as the build plate lowers and rests almost flush on the platform.
4. You need sufficient paper extending beyond the build plate’s edges on all four sides.
5. Mildly press the four sides of the build plate down on the paper with one hand. 
6. Ensure the grub screw is tightened so that the build plate is not dangling at the joint.
7. Tighten the other screws, typically four, until you feel equal resistance on all of them. 
8. Keep mild pressure on the build plate and try to pull, push, and wiggle the paper under it.
9. Repeat the paper test for every side or edge and corner of the build plate. 
10. Raise the 3D printer build plate to the desired height and select a new z-offset. 

It’s not necessary to use the paper method on the 3D printer. You can remove the build plate and perform these steps on a flat and leveled table, glass, or another solid surface. However, you must ensure that the surface is truly flat and leveled. 

To do this, use the straightedge test:

1. Hold the straightedge on a flat table, glass, or another solid and steady surface. 
2. Shine a torch under it and check if any light passes through under the straightedge.
3. Repeat this step at different places on the surface where you will keep the build plate.

This approach requires you to reassemble the build plate on the 3D printer and recheck its alignment on the clamp, along the z-axis, and with the resin tank. Therefore, it’s easier and better to recalibrate, realign, and level a build plate on the 3D resin printer.

Also, you can choose a new z-offset for the flat and leveled build plate. However, this starting point isn’t the home position on 3D resin printers. The homing process will still take the build plate down to its end stop, where its face is almost flush with the platform or resin tank’s base. 

You may need to slightly tweak a few steps discussed in this guide if your 3D printer has distinct features. For instance, some models may not have four screws, the joint could be cubic or like a bulb, and a knob or some kind of adjustor might serve the grub screw’s purpose.

Last but not least, ensure your 3D printer is flat and leveled. No recalibration, flattening, or leveling of the build plate will solve your problems if the 3D printer is slightly tilted. Some SLA, DLP, and LCD printers display notifications if they are not leveled. Fix that before the build plate.  

Conclusion

Ideally, you should not have to re-level the build plate unless the associated hardware parts on your 3D printer fail. However, you must periodically look for scratches and unevenness on the build plate’s surface. If the build plate isn’t desirably flat, you need to smooth the surface again.