Bed Leveling

Owned by Imagine That
Nov 05, 2020
7 min read

Why Do You Need a Level Bed?

Much of the magic in FDM 3D printing is in the filament. The material behaves predictably at certain temperatures, making it possible to control its form, making your 3D printed object possible.

There are various things we must consider when we are using a 3D printer in order to get a successful print. A level print bed is a crucial part of this, as it lets the material extrude evenly across the entire build surface.

After leveling the print bed, we need to adjust the Z height. First we do this manually in order to balance filament flow and bed adhesion. Then we set the value in software, so that the printer knows what the gap is between the nozzle and build plate.

We need both a level build surface and correct nozzle gap to get an even first layer. Then we have the perfect foundation for the rest of our 3D print job.

If either of these settings are off, you can easily tell from the first layer. You just need to know what to look for!

Signs You Need to Level the Print Bed

A level build plate shows a consistent first layer. A few common signs of a non-level bed include:

  • Filament height and width varies across the build surface

  • The gap between lines of filament varies across the build surface

  • Filament is sticking to the build surface only in some places

  • Prints (mostly PLA) warp upwards where they otherwise wouldn’t


Required Tools

Here is a good starting set of tools needed to maintain your bed level and nozzle gap:

  • Index card: For 3D printer bed leveling and nozzle gap adjustment, you’ll need a card of a size you can comfortably hold and slide between the nozzle tip and the build plate. A piece of ordinary office paper cut down to about 100 mm x 40 mm should work. We prefer using a thickness of 120-160 gsm, but you will learn your chosen paper and how it should feel when using it.

  • Screw driver or hex key: Your 3D printer’s bed may require one of these tools to adjust screws on the bed.

  • Heat-resistant gloves, like these ones from Rapicca, are useful for working around the nozzle.

  • A clean cotton cloth and a brass brush, like the Hyde Tools Mini Brush work well for cleaning the nozzle.

  • A razorblade or a spatula can be used to scrape residue from the surface of your build plate. If you already have something like the BuildTak spatula, it should work well, too.

  • Dish soap and a clean, dry cotton cloth will also be useful for removing dust and grime.

  • Isopropyl alcohol, for example this one from MG Chemical, allows one to clean a build surface that is permanently mounted to the 3D printer. Just check that the build surface can handle the cleaning agent.

Preparation

Clean the Nozzle

First things first! If you have any residual plastic on the tip of the nozzle, your 3D printer bed leveling and nozzle gap adjustment will be off. Thankfully, the tip is easy to clean with a dry cotton cloth.

Heat the nozzle to the temperature the last used material was printed at, and wipe off the excess plastic. If that doesn’t do the trick, a brass brush may be used to carefully clean around the tip. Just be careful no to overdo it, otherwise the nozzle may be damaged by the hard brass bristles.

When working close to the hot end, be sure to observe proper safety practices, wear heat-resistant gloves, and use common sense.

Clean the Build Surface

As with the nozzle, your 3D printer’s bed surface also needs to be clean. For a glass build surface, we can mostly use a razor blade or a spatula to scrape of any large residue and debris. The blade will also work for other hard build surfaces, but be sure to not use it on a build plate that might be easily damaged, such as one with a PEI coating.

Once large debris is removed, we can proceed with washing the build plate. If it can be removed, cleaning it in the sink with ordinary dish soap and lukewarm water works quite well. For a non-removable build plate, you can use isopropyl alcohol on a paper towel or cloth. After that, dry it with a soft cloth.

It’s a good idea to not touch the clean build surface with your bare hands, as that can add oils from your skin. We don’t want any grease on the surface, as that can adversely affect bed adhesion. For different types of build surfaces, other techniques may apply, so be sure to check your specifications to avoid damaging your surface.

Hot or Cold?

For the bed leveling process, it doesn’t matter if the bed and nozzle are hot or cold unless you plan to only print with one set of settings. In this case, heating up to those temperatures before leveling can help to ensure your level is exact, but this is not strictly necessary.  For setting the Z height, you should follow the recommendations for your your 3D printer model and type. If you’re unsure, start with a cold nozzle and print bed.

3D Printer Bed Leveling and Nozzle Gap Adjustment

Manual 3D printer bed leveling and Z height adjustment can be a frustrating experience even for seasoned makers. However, as soon as you understand the basics of the process, you will easily master this useful skill.

Many 3D printers have automatic or semi-automatic bed leveling, but manual leveling will give a better looking bottom layer, and is still necessary to make the automatic level more accurate and consistent. Also, when something is wrong with your first layer, you may be able to more easily find the faulty part or setting if you know what’s going on in the leveling process.

1. START BY CREATING SOME WORK SPACE:

Most FDM 3D printer beds are mounted with three or four adjustable screws in the corners or along the sides of the build plate. Adjust each screw a couple of turns to increase the distance between the nozzle and build plate.

2. MOVE THE BUILD PLATE:

Now you want to get the nozzle close to the build plate, either by hand or with the software you use to control the 3D printer. If your printer is set to home to one of the corners of the build plate, simply set it to auto home.

3. MEASURE AND ADJUST:

You want to calibrate the 3D printer bed so that it is as level as possible at all four corners and in the middle.

Move the print head to a corner of the bed and put the index card between the nozzle tip and 3D printer bed. If there is no resistance dragging the index card back and forth between the nozzle and the bed, adjust the closest bed leveling screw to tighten the gap.

Be careful not to put pressure on the 3D printer bed (for example with your hand), as this will push the bed down enough to make the gap bigger than it really is. Use your index card again keep adjusting the screw until you can feel a slight drag from the nozzle and 3D printer bed on the index card.

Repeat the same process on all remaining corners. When the corners are okay, move the print head to the middle of the build plate and check that the same resistance can be felt there. Readjust the screws if necessary.

Lastly, double-check each corner and the center again, as the constant adjustments may have affected other spots. If that’s the case, repeat the entire procedure until all five points are leveled.

5. INSPECT THE FIRST LAYER:

Before running a complete 3D print job it’s a good idea to print only the first layer in order to verify successful bed leveling. If successful, the first layer should look more or less the same over the whole surface. If not, you may need to further adjust your level.

In the case that the layer is uniform but too squished (or not sticking), you may need to adjust your Z offset, changing the amount of space between the nozzle and the bed for the first layer of your print.

Signs The Nozzle Gap is Off

By setting the Z height you decide what size nozzle gap you want. If the gap is too big or too small, you can often tell by looking at the shape of the extruded lines of filament on the build plate. This is useful if the paper you have used to level your bed wasn’t quite the optimal thickness, and your first layer is consequently too thin, or not sticking properly.

The second use of the Z offset setting is to make sure your first layer is exactly the right height, as set in your slicer. This can be measured by printing a test and measuring the thickness with calipers, adjusting the offset value accordingly.

In many printers, the Z offset can be changed directly with the printer’s built-in controls. However, if this is not the case, the setting can usually be found and adjusted in your slicer software as well.

SIGNS THE NOZZLE GAP IS TOO SMALL:

  • The first layer is barely visible or very thin

  • The nozzle plows through filament already on the build plate

  • Filament gathers on the nozzle

  • No filament extrudes onto the build plate

To fix this, you need to increase your Z offset, making the nozzle gap larger.

SIGNS THE NOZZLE GAP IS TOO LARGE:

  • Filament doesn’t stick to the build surface

  • Filament comes out as spaghetti

As opposed to being too small, the solution to having a larger than optimal nozzle gap is to decrease your Z offset, making the gap smaller.

To tune your Z offset, we recommend printing a simple test a few times, adjusting the value between prints to make sure that you have an optimum nozzle gap.