The Most Common Problems With FDM 3d Printers: Troubleshooting Guide

We can create amazing things with a 3D printer as long as nothing goes wrong. But let’s face it, we’ve all encountered annoying problems and glitches that ruined the project no matter what we tried to do to print correctly. Unfortunately, that’s the price we have to pay to create cool useful things. And it’s worth it!

Troubleshooting is a skill on its own and you have to hone yours to become a professional 3D printer (yes, you must become the printer!). Noodling is fun, but we have to research, gather experience, and learn something from our mistakes. The good news is you don’t have to learn exclusively from your own mistakes and unsuccessful projects. Instead, you can learn from an extensive troubleshooting guide where we’ll talk about the most frequent problems you’ll encounter with FDM prints. So let’s get started!

Why won’t it print?

This is the question everyone asks at some point. Whatever you try, the printer just refuses to get the job done. There are a lot of things that can prevent the filament from being extruded, so let’s explore the most common causes and their solutions.

1. The nozzle is too close to the print bed

There’s plenty of filament on the reel and you have a working print heat, but there’s no material going to the print bed.

When that happens, the nozzle is probably not far enough from the print bed. If the nozzle is too close to the bed, the material doesn’t have enough room to be deposited. This issue can also cause missing layers or prevent the filament from correctly adhering to the surface. Furthermore, you might end up with a clogged nozzle as well.

Solution

In most cases, all you need to do is raise the nozzle. Depending on your printer model, you can adjust the Z-axis offset in its settings by inserting a positive value. Remember that a negative offset will bring the nozzle closer to the bed. Fine-tune this setting because if you go too far, the filament won’t stick properly.

Another solution is lowering the print bed. But this isn’t recommended because then you have to spend extra time to make sure the bed is correctly leveled.

2. The nozzle is clogged

The nozzle won’t extrude any material and changing the filament doesn’t help.

The nozzle can easily get clogged because it’s easy to leave a bit of material inside it when changing the filament reel. So the new filament won’t go through because there’s an old piece blocking its path.

This problem can easily be prevented by performing regular maintenance. Before the nozzle gets clogged, you should be able to notice some leftover material in the nozzle (if you check). Before the nozzle gets clogged, there are also signs such as small defects and little spots of differently colored filament. A simple cleaning session will keep your nozzle in perfect condition.

Solution

Use a needle to remove the clog. This is probably the simplest fix. All you need to do is remove the material, heat up the nozzle to melt the leftover filament, and then use a needle or a pin to clear out the blockage.

Another solution is to push the old material through the nozzle by using a fresh piece of filament. To do that, remove the filament and the feeder tube. Heat up the hot end and use some filament to force the old material out of the nozzle. If it doesn’t work initially, you might have to manually push the material because more pressure is needed. But be careful and don’t exert too much force or you’ll damage the printer rods.

If nothing works and the nozzle is severely clogged, you’ll have to disassemble the hot end. If this is your first dismantling operation, make sure to have a video guide handy or take photos and notes with each step you take. Otherwise, you might forget how to put everything back together.

3. The printhead misses the print bed

When this happens you’ll definitely notice it because you’ll hear a troublesome noise. The printhead will miss the bed when it tries to move past its limit on the X- or Y-axis. It’s pretty much impossible to print something when that happens so you need to fix it as soon as possible.

This problem can occur for a variety of reasons, such as a misconfigured system or damaged end stops. If you encounter it with a new printer, the fault probably lies with the configuration, in which case you should go through the setup steps and double-check the firmware.

Solution

Start by checking which printer you selected in the slicer software. If you choose the wrong printer model from the list your printer will attempt to use the configuration files that were meant for that model. All printers are different so the settings won’t match.

If your printer is new and you’ve set it up correctly, the problem might be caused by the out of date of firmware. So make sure you update to the latest version and recheck the settings.

Finally, if nothing helps, you might be dealing with faulty end stops. They’re a bit more challenging to inspect. You’ll have to monitor the movement of the print head and see whether one of the end stops is somehow disconnected. If they seem to be in working order and none of the solutions work, consider changing them with new ones.

4. Fragmented filament

If the filament spool is full and it looks like it’s going through the feeding tube, but nothing comes out, then you might be dealing with a fragmented filament. A breakage can easily go unnoticed, especially when it comes to 3D printers that feed the material directly.

The most likely cause is the filament itself if it’s too old or low quality. This also depends on the type of material. For example, ABS can last for quite a while if it’s not kept in the sun. If the age or environment damages the integrity of the material, it will crumble or fragment itself.

Solution

To fix this problem, start by removing the filament. This will also involve clearing the tube from the hot end and extruder because there’s a chance you have crumbled material there as well. Afterward, heat the nozzle and clean it from any remains.

Alternatively, check your temperature and flow rate settings. Too much heat can damage the filament and if the flow rate is above 100% it can break.

If this happens again with the new filament spool, you should buy a new batch or try a different brand.

5. Slipping filament

This issue can occur at any time while you’re printing and it can happen with high-quality filaments as well. When it happens, there won’t be any new material being extruded.

There are several causes for slipping filament, namely wrong temperature settings, a loose idler tensioner, or clogging, but they shouldn’t be too difficult to resolve. What usually happens is that the gear inside the extruder can no longer drive the filament. The motor continues to spin, but the gear’s teeth won’t manage to grip the material to feed it through the system. Instead, the gear continues to further damage the filament until it slips entirely.

Solution

When the filament starts to slip you’ll notice a strange sound that you shouldn’t be hearing. That’s the first clue that somethings wrong. Next, you might see some material shavings coming out as well. When that happens, the system needs some additional help. So, apply some force gently to manually push the material. The printer should start working correctly soon after getting a nudge in the right direction. Furthermore, if this happens with a new spool of filament, you should check the temperature setting.

If that doesn’t work, sometimes you’ll have to remove the filament to cut off the slipping section and then feed it back into the system. However, if you notice any breakage, the material may be damaged or past its life expectancy. If that happens, you’ll need a new spool.

Finally, if the problem is connected to the idler tension, you should loosen it up a little. Then push the filament through the system and gently tighten it until there's no more slipping.

Print was unsuccessful

Your project looked good to go, but somehow the printing process didn’t go well. Whether the material failed to stick to the print bed or the filament stopped being extruded in the middle of the print, there are many things that can cause an unsuccessful print. So let’s investigate the most common problems.

1. The print didn’t stick

The print not sticking to the print bed is probably one of the most common issues you’ll ever encounter, but it’s not too difficult to solve.

Unfortunately, the object you’re printing can unstick itself at any point in the process, whether it’s during the first layers or the last one. As you can imagine that can be quite infuriating. However, don’t blame the printer because sometimes it’s not its fault. For instance, a print can fail to stick when there’s barely any contact between the object and the platform. In that case, printing without supports or proper adhesion will result in a fail.

Solution

Since the most common issue is the lack of a proper bond between the model and the print bed, we need to improve the texture by adding another material. The simplest thing we can do is add a layer of basic glue to the bed. Just make sure the adhesive is something you can wash out with water. Alternatively, you can use heat-resilient tape.

Next, you need to make sure the platform is properly leveled and clean. If your printer doesn’t have an auto-leveling feature, follow the manual to make all the adjustments. Contaminants, like the oil from your fingers, can also reduce the platform’s grip, so clean it regularly.

Finally, you should consider using a brim, a raft, or adding supports. Small objects will rarely print well without a brim or a raft because they barely come into contact with the platform. Look for those two elements inside the slicer software. The purpose of the brim is to add a specified layer that radiates from the area where the print makes contact with the platform. The downside is that after the print is complete, you’ll need to cut the brim off your model. Alternatively, you can use the raft, which in essence is a base that represents the model’s footprint. The model is printed on top of this layer and you’ll have to snap it off once the print is complete.

As for supports, they’re ideally used when there’s some overhang due to the complexity of the model. They are meant to keep the object together and make sure it doesn’t warp or fall apart.

2. Extrusion stopped halfway

In some cases, there’s no more filament coming through. This usually happens for two reasons. Either there’s a problem with the filament itself, or the nozzle is the one causing the trouble.

Solution

As mentioned before, check your filament first because maybe it just ran out and you need a new spool. It could also be fractured or slipping. So try the solutions for those problems first. If that’s not the case, check the nozzle next because there may be some material clogging it.

3. The supports failed

When you print a complex object you need to use a couple supports, despite the fact they’re a bit annoying to remove. But sometimes the support doesn’t do what it’s supposed to and you end up with warped or cracked supports. In turn, the extruded filament no longer goes exactly where it was supposed to and your print is ruined.

Creating supports is sometimes challenging, even though your slicer software certainly comes with a few presets. But even when you use them, they can fail.

Solution

There are several things you can do to ensure your supports don’t fall apart:

• Choose the right support type: If your model has large overhangs that link sections of the object which are in perfect contact with the platform, you can use zig-zag or line supports. On the other hand, if there’s little contact and you need heavy support, you should use grid-like support or triangle support.
• Use adhesion: A brim or a raft will help the model by offering it a solid foundation.
• Use more supports: This shouldn’t be one of your first choices because they will be challenging to remove. But, they do help in case the model moves in the process.
• Fortify the supports: Printing tall and thin supports is a bad idea because they bend and easily break. Instead, you should build a block-like structure close to the bottom of the support to reinforce it.
• Check the printer’s stability: Sometimes the problem lies in a printer that shakes and vibrates too much. So make sure it's on a stable, even surface and recalibrate it just in case.
• Use fresh filament: As mentioned earlier, old filament loses some of its integrity because it doesn’t keep its characteristics forever. So use a new spool and see if that solves the problem.

Print successful but ugly

You printed your model successfully but it looks horrible. This happens to everyone, so don’t sweat it. There are many things that can go wrong, so let’s explore some of the most common causes for a sight-offending print.

1. Messy base layer

The most troublesome layers are usually the first ones. Sometimes the print just won’t stick properly or there are strange lines appearing on the bottom of the model. Printing details on the bottom layer is also problematic because they tend to blur out.

In most cases, these issues appear when the print bed isn’t correctly leveled. But sometimes the nozzle contributes to the messiness if it’s too close or too far away.

Solution

Start by making sure the platform is leveled, especially if the adjustment process is done manually. Afterward, inspect the nozzle to determine the correct distance. Finally, to preserve the details on the bottom of the model you should gradually lower the temperature of the platform until the material can adhere to it without losing print quality.

2. Warping print edges

One of the most common issues is the bending of the model’s base. This causes the print to move upwards. When that happens, the model can come unstuck or cracks may appear.

Warping is caused due to the nature of plastic. When the material cools off, it contracts. That’s perfectly normal and fine if it happens slowly. But if the plastic cools off too quickly, it contracts suddenly and warps or cracks.

Solution

The first thing you should do is use a heated print platform. This is by far the easiest solution. You’ll be able to set the temperature just under the material’s melting point and allow the plastic to gradually transition from hot to cold.

Alternatively, you can use an adhesive on the platform. Stick glue should work sufficiently well if the edges of the model tend to warp only slightly.

3. Bad infill

Sometimes the interior of the print ends up broken or missing altogether. Usually, the internal structure is negatively affected due to having the wrong settings in the slicing application. However, in some cases, it’s caused by a partially clogged nozzle.

Solution

Make sure you configured the correct infill density inside the slicing software. It shouldn’t be less than 20%. Additionally, if the print is large, the value should be greater because the model needs more support.

Next, you should check the infill speed and decrease it if necessary. This setting affects the structure’s quality, so if it’s not looking good, you should decrease the value.

Finally, you should try changing the infill pattern if none of the above solutions work. Look into what’s more appropriate; a triangle pattern, a grid pattern, and so on.

If these settings seem perfectly fine, you should inspect the nozzle. All it takes is a slight clogging and the printing of the interior will be affected.

4. Tall models have cracks

Tall objects are more susceptible to cracking. Why? The top layers simply cool off faster than the bottom ones, and as already mentioned, if plastic cools too quickly it cracks. And unfortunately, having a heated bed won’t help in this case.

Solution

Start by increasing the temperature of the extruder in increments of 10ºC but be careful not go beyond the material’s limits. Furthermore, you can also inspect your fans. If they’re pointed towards the model you should decrease their speed.

5. The layers are misaligned

The quality of the print is often affected by the layers not aligning correctly. If that’s the case, you should notice misalignments in the exterior structure and therefore uneven faces. Usually, the model ends up being disproportionate.

Gradually, various printer parts become loose and need to be tightened. Otherwise, some layers may end up incorrectly aligned. So, inspect the belts and rods and make sure they're tight, cleaned, and well-maintained.

Solution

• Taking care of the belts: Check the belts first. Pinch them together and if you feel a bit of resistance from both of them, then they’re correctly tightened. Otherwise, you might feel a difference between them. For example, if the upper one feels tighter, then you need to adjust them. Depending on your printer model, you can do this using the built-in tighteners, or do it manually.
• Taking care of the rods: After a while, the rods will gather debris, which adds to friction. More friction translates here to layer shifts. In this case, all you need to do is wipe the rods and oil them up. However, if they’re warped in some way you’ll probably have to replace them. Straightening them by hand can’t be done accurately.

6. The print looks warped or melted

The plastic materials we use for 3D printing are fairly resilient and they can handle overheating quite well, but this characteristic makes it hard for us to notice when the temperature is set too high. If the hot end is much hotter than it should be, the model will be printed in uneven layers or look as if it’s melting like a piece of wax. The bottom line is that overheated filament is the culprit in most of these cases.

Solution

Start by checking which temperature setting is the ideal one for the type of material you’re using. Perhaps you changed the type of filament from the last print and you forgot to update the temperature range.

If overheating is indeed the problem, lower the temperature gradually, in small increments of five degrees. In addition, you can improve the printing speed and adjust the cooling system to blow towards the hot end.

7. The stringing effect

One of the worst things that can happen to a print is having it ruined by stringing. Sometimes when the head travels, it drips melted filament, which stretches itself like a string.

Solution

Enable the ‘retraction’ function in your slicing application. Its purpose is to retract the material into the nozzle before moving the head over the open area. This way we won’t end up with molten plastic dripping and stretching into strings behind the head. Most programs have this function ready at the push of the mouse button, with default values so all you need to do is enable it. However, you can make adjustments to improve it if you think it’s necessary.

In addition, you can also adjust the minimum travel. Sometimes retraction just isn’t enough, so start reducing the travel value gradually, in small 0.5mm increments. The stringing should stop eventually.

If all else fails, grab the sharpest tool you have and cut the filament strings. This isn’t the ideal solution and it can leave imperfection, so use it only if nothing else works for you.

Final Thoughts

3D printing is fun and rewarding, but it comes with challenges and you need to be ready to greet them. Troubleshooting is simply part of the work and even though printing an unsuccessful model is frustrating, we can learn something from it. So, when you encounter a printing problem, start looking for the cause of it by eliminating every possibility. Anything can be adjusted or replaced, but you will always gain experience.