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Troubleshooting Guide to 22 Common 3D Printing Problems

3D printing problems

Frustrated with Fused Filament Fabrication? Read our 3D printer troubleshooting guide to the most common 3D printing problems and their solutions.

It’s amazing what your 3D printer can produce. But we’ve all had those infuriating moments when, despite everything, a seemingly simple model just refuses to print successfully.

You’ve checked the model, seen countless others make it without issue, but try as you might it just won’t print. What is it that keeps going wrong?

Here at ALL3DP, we’ve had our fair share of print failures. But the upside to those failures is that we’ve become finely tuned to recognizing and solving many common 3D printing problems.

Direct from our 3D printer troubleshooting experience, we’ve collected together 22 of the most common 3D printing problems we’ve had and replicated them here.

This article will help you to quickly diagnose your 3D printing issues, and find the solution with our 3D printer troubleshooting guide. Discover how and when these 3D printing problems occur, and the steps you can take to avoid them in future.

Important note: If you don’t know the name of your problem you can zap through all problems by clicking on the images.

22 Common 3D Printing Problems

  1. Warping
  2. Elephant Foot
  3. More First Layer Problems
  4. Layer Misalignment
  5. Missing Layers
  6. Cracks In Tall Objects
  7. Pillowing
  8. Stringing
  9. Under-Extrusion
  10. Over-Extrusion
  11. Shifting Layers
  12. Blocked Bowden Nozzle
  13. Snapped Filament
  14. Stripped Filament
  15. Broken Infill
  16. Ghosting of the Internal Structure
  17. Gaps Between Infill and Outer Wall
  18. Non-Manifold edges
  19. Model Overhangs
  20. Leaning Models
  21. Misaligned Layers
  22. Extrusion Temperature Too High

3D Printing Problems #1: Warping

3D Printing Problems: Warping

What’s the 3D Printing Problem?

At the base of the model, the print bends upwards until it’s no longer level with the print platform. This can also result in horizontal cracks in upper parts.

What’s Causing this 3D Printing Problem?

Warping is common as it’s caused by a natural characteristic of the plastic. As the ABS or PLA filament cools it starts to contract very slightly; the problem of warping arises if the plastic is cooled too quickly.

3D Printer Troubleshooting: Warping

  1. Use a heated print platform. The easiest solution is to use a heated print platform and to set the temperature to a point just below the plastics melting point. This is called the “glass transition temperature”. If you get that temperature right then the first layer will stay flat on the print platform. The print platform temperature is often set by the slicer software. You’ll normally find the recommended temperature for your filament printed on the side of the packaging or on the spool.
  2. Apply glue. If you still find your print lifting at the edges then apply a tiny amount of stick glue evenly on the bed to increase adhesion.
  3. Try a different platform type. Change your print bed to one that offers better adhesion. Manufacturers such as Lulzbot use a PEI (Polyetherimide) print surface that offers excellent adhesion without glue. XYZPrinting supply a textured tape in the box with some of their printers, basically a large sheet of masking tape, and again adding this works excellently, although only with nonheated print platforms. Zortrax 3D printers have a perforated print bed, models weld themselves to this surface eliminating the issue completely.
  4. Level the Print platform. Print platform calibration can be another cause, run through the calibration process to check that the bed is level and nozzle height is correct.
  5. Increase contact. Increasing the contact between the model and bed is an easy fix and most print software has the option to add rafts or platforms.
  6. Adjust advanced temperature settings. If all else fails then you’ll need to take a look at your advanced print settings both on your printer and in your print software. Try increasing the print bed temperature by increments of 5 degrees.
    In the slicer software take a look at the fan cooling, this is usually set so the cooling fans switch to full power at a height of around 0.5mm, try extending this to 0.75 to give the base layers a little more time to cool naturally.
    Even if your printer has a heated print platform, it’s always recommended that you use glue and regularly calibrate the bed level.

3D Printing Problem Checklist: Warping

  • Use a heated print platform
  • Add Stick glue to the print platform
  • Swap from glass to an adhesive print bed
  • Calibrate print bed
  • Add platforms or rafts
  • Adjust advance the temperature and fan settings

Back to overview


3D Printing Problems #2: Elephant Foot

3D Printing Problems: Elephant Foot

What’s the 3D Printing Problem?

The base of the model is slightly bulging outwards, otherwise known as “elephant foot”

What’s Causing this 3D Printing Problem?

This ungainly effect can also be caused by the weight of the rest of the model pressing down the first layers when the lower layers haven’t had time to cool back into a solid – particularly when your printer has a heated bed.

3D Printer Troubleshooting: Elephant Foot

  1. The right balance. To stop elephant foot appearing in your 3D prints the base layers of the model need to be cooled sufficiently so that they can support the structure above, but if you apply too much cooling to the base layers you can create warping. Getting the balance right can be tricky, start by lowering the temperature of the print platform by intervals of 5 degrees, (within +/- 20 degrees of the recommended temperature). If your  Bottom / Top Thickness is set to 0.6mm then start the fan after the fan at a slightly lower height.
  2. A level base. More often than not the majority of print issues can be traced back to the level of the print platform. Each printer has a slightly different technique for print platform leveling. Start by using your printers manufacturers recommended procedure. Then print a calibration cube and just watch how the filament is laid down. From printing of the cube you should be able to see if the filament is being laid down evenly, if the nozzle is too close to the print platform and scraping through the molten filament or too high and causing the filament to blob.
  3. Raise the nozzle. Just raising the height of the nozzle slightly can often help, but be careful too high and it won’t stick to the platform.
  4. Chamfer the base. If all else fails then another option is to chamfer the base of your model. Of course, this is only possible if you have either designed the model yourself or you have access to the original file. Start with a 5mm and 45º chamfer, and experiment to get the best result.

3D Printing Problem Checklist: Elephant Foot

  • Balance print platform temperature and fan speed
  • Level the print platform
  • Check the nozzle height
  • Chamfer the model base

Back to overview


3D Printing Problems #3: More First Layer Problems

3D Printing Problems: More First Layer Problems

What’s the 3D Printing Problem?

The first layer does not stick properly, and some parts come loose. There are unwanted lines at the bottom.

What’s Causing this 3D Printing Problem?

These 3D printing problems are typical signs that the print bed hasn’t been leveled properly. If the nozzle is too far away from the bed, the bottom surface often shows unwanted lines, and/or the first layer does not stick. If the nozzle is too close, blobs may be the result.

Also important: the print bed has to be as clean as possible. Fingerprints on the plate can prevent the first layer from sticking to the plate.

3D Printer Troubleshooting: More First Layer Issues

  1. Level the print bed. Every printer has a different process for print platform leveling, some like the latest Lulzbots utilize an extremely reliable auto leveling system, others such as the Ultimaker have a handy step-by-step approach that guides you through the adjustment process and then there’s the Prusa i3 that takes skill and determination.
  2. Adjust the nozzle height. If the nozzle is too high then the filament won’t stick to the platform, to low and the nozzle will actually start to scrape the print off.
  3. Clean the print platform. Every so often it’s a good idea to give the glass print platform a good clean, especially if you apply glue. The grease from your fingerprints and the excessive build up of glue deposits can all contribute to the nonstickiness of the print platform.
  4. Add glue. Applying a thin layer of glue to the print platform will help add a little more adhesion if you do this make sure you give the bed a clean at regular intervals as the over application of glue can have the reverse of the desired effect.
  5. Textured sheet for cold print beds. On cold print platforms, a common solution is to apply a stick-on film or sheet that increases the adhesive properties of the print platform.

3D Printing Problem Checklist: More First Layer Issues

  • Level the print platform
  • Check nozzle height
  • Clean print platform
  • Add Glue
  • Textured sheets for cold platforms

Back to overview


3D Printing Problems #4: Layer Misalignment

3D Printing Problems: Layer Misalignment

What’s the 3D Printing Problem?

Some layers in the middle of the objects have shifted.

What’s Causing this 3D Printing Problem?

The printer belts aren’t well tightened. The top plate isn’t fastened and wobbles around independent of the bottom plate. One of the rods in the Z axis is not perfectly straight.

3D Printer Troubleshooting: Layer Misalignment

  1. Check the belts. Start by checking each of the belts are tight but not over tight. You should feel a little resistance from the two belts as you pinch them together. If you find that the top section of the belt is tighter than the bottom then this is a sure fire sign that they need a tweak and tighten.
  2. Check the top plate. Check the top plate and all rods and attachments at the top of the printer and make sure everything is tight and aligned.
  3. Check the Z axis rods. Many printers use threaded rods rather than lead screws and although these do the job they do have a tendency to bend over time. Don’t worry about dismantling your printer to see if they’re straight, simply use the software such as ‘Printrun’ to move the print head up or down. If one of the Z axis rods is bent you’ll instantly see. Unfortunately, it’s almost impossible to accurately straighten a rod once it’s bent, but on the upside, it’s a good excuse to replace the old threaded rods for lead screws.

3D Printing Problem Checklist: Layer Misalignment

  • Check the tension in the belts
  • Check there’s no movement in the top plate
  • Make sure the Z axis rods are straight

Back to overview


3D Printing Problems #5: Missing Layers

3D Printing Problems: Missing Layers

What’s the 3D Printing Problem?

There are gaps in the model because some layers have been skipped (in part or completely).

What’s Causing this 3D Printing Problem?

The printer failed to provide the amount of plastic required for printing the skipped layers. This is called (temporary) under-extrusion. There may have been a problem with the filament (e.g. the diameter varies), the filament spool, the feeder wheel or a clogged nozzle.

Friction has caused the bed to temporarily get stuck. The cause may be that the vertical rods are not perfectly aligned with the linear bearings.

There is a problem with one of the Z axis rods or bearings. The rod could be distorted, dirty or had been oiled excessively.

3D Printer Troubleshooting: Missing Layers

  1. Mechanical check. It’s good practice to give your 3D Printer the once over every now and again and the appearance of gaps in your 3D print are always a good sign that now is the time to give your 3D printer some love and attention. Start off by checking the rods and make sure that they’re all seated into either bearings or clips and haven’t popped out, shifted or moved even slightly.
  2. Rod alignment Check. Make sure that all rods are still in perfect alignment and haven’t shifted. You can often tell by switching off the power (or disabling steppers) and then gently moving the print head through the X and Y axis. If there is any resistance to the movement then something is wrong and it’s usually pretty easy to tell if this is due to misalignment, a slightly bent rod or one the bearings.
  3. Worn bearing. When bearings go they usually let you know about it by creating an audible din. You should also be able to feel uneven motion in the print head and when printing the machine looks like it’s vibrating slightly. If this is the case unplug the power and move the print head through the X and Y to locate the region of the broken bearing.
  4. Check for oil. Lubricating the joints is easy to forget, but keeping everything well oiled is essential to the smooth running of the machine. Sewing machine oil is ideal and can be purchased for almost any haberdashery at a relatively inexpensively price. Before you go applying liberally just check that the rods are clean and free of dirt and printing debris, a quick wipe of the rods before applying fresh coat of oil is always a good idea. When all rods look clean just dab on a little, but not too much. Then use print such as Printrun to move the head through the X and Y axis to make sure that the rods are evenly covered and moving smoothly. If you add a little too much oil don’t worry just wipe some off with a lint free cloth.
  5. Under-Extrusion. The final issue could be under-extrusion and finding the solution for this can cumbersome. See 3D Printing Problems #9: Under-Extrusion.

3D Printing Problem Checklist: Missing Layers

  • Check over the mechanics and make sure everything is tight
  • Double check the printer’s construction and alignment
  • Listen out for worn bearings and bent rods
  • Add a little oil to keep things running smooth

Back to overview


3D Printing Problems #6: Cracks In Tall Objects

3d-printing-problem-cracked-layer

What’s the 3D Printing Problem?

There are cracks on the sides, especially on taller models. This can be one of the most surprising issues in 3D Printing as it tends to manifest itself in larger prints, and usually whilst you’re not looking.

What’s Causing this 3D Printing Problem?

In higher layers, the material cools faster, because the heat from the heated print bed doesn’t reach that high. Because of this, adhesion in the upper layers is lower.

3D Printer Troubleshooting: Cracks In Tall Objects

  1. Extruder temperature. Start by increasing the extruder temperature; a good start would be to increase it by 10ºC. On the side of your filament box you’ll see the working hot end temperatures, try to keep the temperature adjustment within these values.
  2. Fan direction and speed. Double check your fans, make sure that they’re on and aimed at the model. If they are try reducing their speed.

3D Printing Problem Checklist: Cracks In Tall Objects

  • Check the hot end temperature and raise at 10-degree intervals
  • Check the position and speed of the cooling fans

Back to overview


3D Printing Problems #7: Pillowing

3D Printing Problems: Pillowing

What’s the 3D Printing Problem?

The top surface of the print shows unsightly bumps or even holes.

What’s Causing this 3D Printing Problem?

The two most common causes are improper cooling of the top layer and that the top surface isn’t thick enough.

3D Printer Troubleshooting: Pillowing

  1. Filament size. More common with 1.75 mm filament. Pillowing is an issue that can affect all 3D printers, however, it’s far more common on those using 1.75 mm filament over 2.85mm.
  2. Check the fan position. Cooling is normally the issue start by checking your fans. As the print starts your printers fans will be set to low or off, after the first few layers have printed they should kick into action. Check that the fans around the hotend start to spin, then as the print finishes check the fans are all good and working. If all seems OK just double check that the direction of the fans is correct and that they’re pushing cool air towards your print and not elsewhere.
  3. Set fan speed in G-Code. Another cooling issue happens when each successive top layer of molten plastic is applied. As it covers the inner support structure it needs to be cooled quickly to avoid falling into the holes between the supports. The speed of the fans can be adjusted in the G-Code, a common G-Code for Fan On is M106 and is M107 Fan Off. You then just need to the Fan speed to maximum for those top layers.
    An example would for a 1cm x 1cm cube printer at 0.1mm layer height. The G-Code in this case output through CURA for the Prusa i3, we can look through the code and see that there are 97 layers. Knowing that we have a ‘Bottom / Top Thickness setting’ of 0.6mm we can look back to ;LAYER:91 then in the line after add M106 S255. M106 sets the fan going and S255 sets it to full blast.
  4. Increase top layer thickness. The easiest solution is to increase the top layer thickness. Most applications will enable you to do this in the advanced section, under the ‘Bottom / Top Thickness setting’. You’re aiming for at least 6 layers of material normally and up to 8 for smaller nozzles and filament. If your layer height is therefore set to 0.1mm then set the ‘Bottom / Top Thickness setting’ to 0.6mm. If the effect of pillowing still exists then increase to 0.8mm.

3D Printing Problem Checklist: Pillowing

  • Go large and increase the filament size
  • Make sure the fans are up to speed and positioned
  • Manually set the fan speed
  • Increase the top layer thickness

Back to overview

3D Printing Problems #8: Stringing

3D Printing Problems: Stringing

What’s the 3D Printing Problem?

There are unsightly strings of plastic between parts of the model.

What’s Causing this 3D Printing Problem?

When the print head moves over an open area (otherwise known as travel move), some filament has dripped from the nozzle.

3D Printer Troubleshooting: Stringing

  1. Enable Retraction. Retraction is an important factor when it comes to quality of finish and can be enabled through most slicing software. Its function is pretty simple and works by retracting the filament back into the nozzle before the head moves. The idea is that it avoids molten filament from trailing behind the head creating thin strings in its wake.
  2. One click retraction activation. Most applications such as Cura offer a one click activation option, this uses a set of default parameters and for the most part is perfectly adequate. However, if you want a few more options there’s often a more settings buttons. Here you can adjust the minimum travel of the head before retraction is activated.
  3. Minimum travel (mm). Reducing the minimum travel is usually the quickest fix for stringing if the standard retraction isn’t doing the job. Drop the value in 0.5mm until stringing is stopped. Activating retraction will increase your print speeds.
  4. Just cut them off. This isn’t the most elegant of solutions but simply taking a scalpel to the strings is quite often the quickest and easiest solution, and has the benefit that it doesn’t increase print times.

3D Printing Problem Checklist: Stringing

  • Enable retraction
  • Adjust the minimum travel before retracting starts
  • Just clean the print with a scalpel

Back to overview

3D Printing Problems #9: Under-Extrusion

3D Printing Problems: Under-Extrusion

What’s the 3D Printing Problem?

Under-extrusion is when the printer cannot supply the material needed (or as fast as needed). Under-extrusion results in thin layers, in layers with unwanted gaps, or in missing layers entirely (see 3D Printing Problems #5: Missing Layers).

What’s Causing this 3D Printing Problem?

There are several possible causes. First, the diameter of the filament used does not match the diameter set in the slicing software. Secondly, the amount of material that is extruded is too low because of faulty slicer software settings. Alternatively, the flow of the material through the extruder is restricted by dirt in the nozzle.

3D Printer Troubleshooting: Under-Extrusion

  1. Check the filament diameter. Start with the simplest issue, have you set the correct filament diameter in the slicing software. If you’re unsure about the diameter the value along with the recommended temperature is usually printed on the box.
  2. Measure the filament. If you’re still not getting the results you want and filament flow is the issue, then use a set of calipers to double check the filament diameter. You should be able to tweak the filament diameter settings accurately in the slicer software settings.
  3. Check the head. After printing, most printers will lift the printhead away from the print base. Quickly check that the nozzle is clear from a build up of filament and dirt.
  4. Set the extrusion multiplier. If there is no mismatch between actual filament diameter and the software setting, then check the extrusion multiplier (or flow rate or flow compensation) setting may be too low. Each slicer application will handle this slightly differently but the principle is to increase the setting in steps of 5% and then restart the print process.
    In Simplify3D open the Edit Process Settings dialog and go to the Extruder tab – the Extrusion multiplier setting of 1.0 corresponds to 100%; In Cura open the Material tab and increase the Flow setting (you may need to enable the Flow setting through the Preferences dialog).

3D Printing Problem Checklist: Under-Extrusion

  • Check the filament diameter
  • Use calipers to measure the filament diameter
  • Check that the hot end is clear
  • Adjust the extrusion multiplier at 5% intervals

Back to overview

3D Printing Problems #10: Over-Extrusion

3D Printing Problems: Over-Extrusion

What’s the 3D Printing Problem?

Over-extrusion means that the printer supplies more material than needed. This results in excess material on the outside of the model printed.

What’s Causing this 3D Printing Problem?

Typically, the Extrusion multiplier or Flow setting in your slicing software is too high (see the section above)

3D Printer Troubleshooting: Over-Extrusion

  1. Extrusion multiplier. Open your slicer software and check that you have the correct Extrusion multiplier selected.
  2. Flow setting. If that all looks correct then decrease the Flow setting in your printer’s software.

3D Printing Problem Checklist: Over-Extrusion

  • Check you have the right extrusion multiplier settings
  • Decrease the filament flow settings

Back to overview

3D Printing Problems #11: Shifting Layers

3d printing problems

What’s the 3D Printing Problem?

The lower and top layers shift so that you get a stepping effect through the print. Usually it’s quite subtle, but these images shows a print with a more pronounced effect.

What’s Causing the 3D Printing Problem?

There’s a variety of reasons for shifting layers, and these can be as simple as someone knocking the printer during the print process! More involved shifting layer problems can be down to bent or misaligned rods, or even the nozzle catching on the print and causing a slight shift in position of the platform.

3D Printer Troubleshooting: Shifting Layers

  1. Check that the printer is on a stable base. Place the printer on a stable base and in a location where it will avoid being knocked, pocked and generally fiddled with. Even a small nudge of the printer can shift the print base and cause issues.
  2. Check the print base is secure. Most 3D printers use some form of detachable print base. Although this is handy when it comes to removing prints, and of course avoids damage to the printer, it also means that over time clips and screws can work loose. Make sure that when you reinstall the print platform it’s clipped or bolted tightly in place to avoid any slip or movement.
  3. Watch out for warped upper layers. If you’re printing a high quality print upper layers can easily warp if cooled too quickly. As the layers warp they rise and can cause an obstruction to the nozzle as it moves, in most cases the print will release from the platform, but if it doesn’t the powerful stepper motors can push the print and platform around.  If your prints are suffering from warping in the upper layers try reducing the speed of the fans slightly.
  4. Printing too fast for your machine. It is possible to speed up the print times for your machine by increasing temperature and flow. However whilst this may result in the filament flowing in the correct quality the rest of the machine may struggle to keep up. If you hear a clicking during printing this could  be a sign that the printer is going to fast. If you do hear a click the first port of call is to check that the filament isn’t slipping, before you take a look at the actual printer speed. To adjust your printers speed open up your slicer software and change the print speed.
    In Simply 3D go to ‘Other > Default Printing Speed (mm/min)’
    In Cura go to ‘Basic > Print Speed (mm/s)’
  5. Check the belts. If layers are still shifting then it’s time to check the belts. A quick check is to just go around all belts and pinch the two together. The tension in each belt should be the same, if not then you’ll need to adjust the belt position to even out the belt tension. Over time the rubber belts will stretch (You can often tell if they do as they’ll start to slip on the drive pulleys), if there is quite a bit of play in the belts then it’s time to replace them with new ones. Over tight belts can also be an issue but this is usually only a problem if you’ve built the machine yourself. Some printers such as the Prusa i3 have belt tensioning screws that enable you to easily adjust the belt tensions.
  6. Check the drive pulleys. These are the usually connected directly to a stepper motor or to one of the main rods that drives the print head. If you carefully rotate the pulley you’ll see a small grub screw. Hold onto the rod and taking hold of the attached belt and then tug the belt and try to force the pulley to turn. You should find that there is no slip between the pulley and stepper or rod, if there is tighten the grub screw and try again.
  7. Check the rods are clean and give them some oil. Over time debris can build up on the rods which means that at some points along their length they cause more friction than others, which in turn can affect the free movement of the head and again cause layer shifting. A quick wipe and re-oil of the rods usually solves the issue.
  8. Bent or misaligned rods. If you see the print head falter at certain points then it could be that one of the rods has become slightly bent. You can usually tell by switching off the machine so there’s no power going through the steppers and then move the print head through the X and Y axis. If you feel resistance then you know something is amiss. Start by seeing if the rods are aligned, if they are then remove the rods and roll them on a flat surface. If any are bent then it will be quite obvious.

3D Printing Problem Checklist: Shifting Layers

  • Check that the printer is on a stable base.
  • Check the print base is secure.
  • Watch out for warped upper layers.
  • Printing too fast for your machine.
  • Check the belts.
  • Check the drive pulleys.
  • Check the rods are clean and give them some oil.
  • Bent or misaligned rods.

Back to overview

3D Printing Problems #12: Blocked Bowden Nozzle

3D Printing Problems Blocked nozzle

What’s the 3D Printing Problem?

You initiate a print job but whatever you try, nothing comes out of the nozzle. Extracting the filament and reinserting doesn’t work.

What’s Causing the 3D Printing Problem?

A small piece of filament has been left behind in the nozzle after changing spools, often because the filament has snapped off at the end. When the new filament is loaded, the piece of old filament that is left in the nozzle doesn’t allow the new filament to be pushed through.

Alternatively, a build up of molten plastic in the end of the nozzle has hardened and will need manual removal. Specialist, cheap or old filaments are a common cause.

3D Printer Troubleshooting: Blocked Bowden Nozzle

  1. Unblock with a needle. If you’re lucky then unblocking can be a quick and easy process. Start by removing the filament. Then using the control panel select the “heat up nozzle” setting and increase to the melting point of the stuck filament. In the case of the Ultimaker 2 go to Maintenance > Heat Up nozzle. For PLA set the temperature to 220 C. Once the nozzle reaches the correct temperature, use a small pin to clear the hole (being careful not to burn your fingers). If your nozzle is 0.4mm then you need a pin that is smaller; an airbrush cleaning kit works perfectly. It’s also worth getting a brass cleaning brush to remove any filament build-up on and around the nozzle.
  2. Push old filament through. If you find that the nozzle is still blocked then you may be able to push the filament through with another bit of filament. Start by removing the filament as before and then remove the feeder tube from the print head. Heat up the hot end to 220 C for PLA and then using another piece of filament push this through from the top to try to force the stuck filament in the nozzle out. Usually if new filament hasn’t succeeded in unblocking then the extra pressure you can exert by hand might just do the job. However don’t push to hard as you’ll bend the horizontal printer rods.
    Once the end clears use a needle to push through the nozzle and a brush to clean any filament excess.
  3. Dismantle and rebuild the hotend. In extreme cases when the nozzle remains blocked, you’ll need to do a little surgery and dismantle the hot end. If you’ve never done this before then it’s a good idea to make notes and take photographs so you know where everything fits when you reassemble. Start by removing the filament, then check your printer’s manual to see exactly how to dismantle the hot end.

In the case of the Ultimaker 2, it’s all quite straightforward. At all times during this procedure be aware that the hot end will get hot so a pair of heat proof gloves is advised (e.g. welder’s gloves).

For the Ultimaker 2 move the print head to the centre of the printer. Undo the four screws on top of the print head and let the hot end and fans hang down.
Increase the temperature of the hot end to 220 C (For PLA) and wait for the hot end to reach temperature. Once the printer reaches the correct temperature switch off the power.

Holding onto the plastic fan housing use a pair of tweezers through the top of the nozzle to grab hold of the offending filament and extract.

Use a needle to push all the way through and then a brass cleaning brush to remove any excess filament.

Switch the printer off and leave to cool.

Once completely cool reassemble, switch on and load a new spool of filament.

3D Printing Problem Checklist: Blocked Bowden Nozzle

  • Heat the nozzle and clean with a needle and brass cleaning brush
  • Remove the feeder tube and try pushing the filament through with another piece of filament
  • Dismantle the hot end and see if you can extract the filament blockage

Back to overview

3D Printing Problems #13: Snapped filament

3d printing problems

What’s the 3D Printing Problem?

The filament spool still looks full, and when you check there appears to be filament in the feed tube, but nothing’s coming out of the nozzle. This is more of an issue with Bowden feed printers than direct feed as the filament is hidden so breakages aren’t always immediately obvious.

What’s Causing the 3D Printing Problem?

Caused by a number of issues but primarily old or cheap filament. Although the majority of filaments such as PLA and ABS do last a long time, if they’re kept in the wrong conditions such as in direct sun light then they can become brittle. Then once fed into the printer no amount of adjustment is going to help.

Another issue is filament diameter, and this can vary through manufacturer and batch. Sometimes if the idler tensioner is too tight then some filament that still has a good amount of life left in it can snap under the pressure.

3D Printer Troubleshooting: Snapped Filament

  1. Remove the filament. The first thing to do is to remove the filament from the printer in the usual way. In the case of the Ultimaker select Maintenance and Change Material. As the filament will usually have snapped inside the tube you’ll need to remove the tube from both the extruder and hotend. Then heat the nozzle and pull out the filament.
  2. Try another filament. If after reloading the filament it happens again, use another filament to check to see if it’s not just the old brittle filament that should be disposed off.
  3. Loosen the idler tension. If the new filament snaps check that the idler tensioner isn’t too tight by loosening all the way. As the print starts tighten until there is no slippage of the filament.
  4. Check the nozzle. Check the nozzle isn’t blocked and give it a good clean.
  5. Check flow rate and temperature. If the problem continues check that the hotend is getting hot and to the correct temperature. Also check that the flow rate of the filament is at 100% and not higher.

3D Printing Problem Checklist: Snapped Filament

  • Check the filament isn’t past its best
  • Check the filament diameter
  • Adjust the idler tension
  • Check that the hot end is clear and reaches the correct temperature
  • Set the flow rate to 100%

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3D Printing Problems #14: Stripped filament

3D Print Problems - Stripped filament

What’s the 3D Printing Problem?

Stripped or slipping filament can happen at any point of the print process, and with any filament. The result is that no filament is extruded from the hot end bringing your print to an abrupt end.

What’s Causing the 3D Printing Problem?

Blockage, loose idler tensioner, wrong hot end temperature, these are just a few of the common causes, but all are usually easy to correct. The result of the problem is that the knurled nut or toothed gear in the extruder is unable to pull or push the filament through the printer. As the motor spins the small teeth on the gear that would usually grip and feed the filament through the system, instead wear it away until there is no longer any grip, and the gear and filament slip.

3D Printer Troubleshooting: Stripped Filament

  1. Help feed the system. If the filament has just started to slip, you can usually tell by the noise and the appearance of plastic shavings, then apply some gentle pressure to the filament to help it through the system. This will often help to get the machine printing smoothly again.
  2. Adjust the Idler tension. Start by loosing the idler, feed in the filament and tighten until it stops slipping. Filaments vary in diameter so although the idler will absorb some difference in diameter some filaments will require fine adjustment.
  3. Remove the filament. In most cases you’ll need to remove and replace the filament and then feed it back through the system. Once the filament has been removed cut the filament below the area that shows signs of slipping and then feed back into the system. If the filament has snapped it may be passed its usable best. Try it again and if it snaps again and you find the filament appears brittle discard and use another filament.
  4. Check the Hot end temperature. If you have just inserted a new filament as the issue started, double check that you have the right temperature.

3D Printing Problem Checklist: Stripped Filament

  • Help feed the system
  • Adjust the idler tension
  • Remove the filament
  • Check the hot end temperature

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3D Printing Problems #15: Broken Infill

3D Printer Problems - Broken infill

What’s the 3D Printing Problem?

The internal structure of your print is missing or broken.

What’s Causing this 3D Printing Problem?

There are a number of reasons for the misprinting of the internal structure. The most common is incorrect settings within the slicing software, but it can also be due to a slightly blocked nozzle.

3D Printer Troubleshooting: Broken Infill

  1. Check the Fill density. In your slicing software check the infill density. A value of around 20% is normal; any less than this and you’re likely to have issues. For larger prints you may want to increase this to ensure that the model has enough support.
  2. Infill Speed. The speed at which the infill is printed can have a major effect on the quality of the structure. If the infill is looking week then decrease the infill print speed.
  3. Change the pattern. Most slicing software enables you to change the internal structure. You can have a grid pattern, or triangle, honeycomb, and more. Try selecting a different option.
  4. Check your nozzle. It might be that there is a slight blockage in the nozzle. While the blockage doesn’t effect the printing of the thicker exterior walls, because there is less flow for the internal structure the filament is getting caught.

3D Printing Problem Checklist: Broken Infill

  • Check and adjust the Fill density
  • Decrease the Infill Speed
  • Try a different infill pattern
  • Check your nozzle for blockages

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3D Printing Problems #16: Ghosting of the Internal Structure

3D Printing Problems - Ghosting

What’s the 3D Printing Problem?

The final print looks fine but an outline of the internal support structure can be seen through the walls of the print.

What’s Causing this 3D Printing Problem?

The issue with ghosting happens due to the infill encroaching into the path of the perimeter. This effect is most visible when your print has thin walls. The problems is caused by the infill structure overlapping with the perimeter line as it’s being laid down. Although this ghosting is an issue it’s actually an important part of the printing process, as it helps the internal structure bond effectively to the external walls. Luckily it’s very easy to overcome.

Another cause of ghosting can be that you have set an incorrect wall thickness in relation to the size of nozzle that you’re using. In normal print conditions the size of the nozzle should be directly related to the nozzle size, so if you have a 0.4mm nozzle then the wall thickness should be a multiple of this, either 0.4, 0.8, 0.12 and so forth.

3D Printer Troubleshooting: Ghosting of the Internal Structure

  1. Check the shell thickness. Make sure that the value you have selected for the shell thickness is a multiple of the nozzle size.
  2. Increase the shell thickness. The easiest solution is to increase the shell thickness. By doubling the size it should cover any overlap caused by the infill.
  3. Use Infill after perimeters. Most slicing software will enable you to activate Infill prints after perimeters.
    • In Cura open up the ‘Expert Settings’ and under the Infill section tick the box next to ‘Infill prints after perimeters’
    • In Simply3D Click ‘Edit Process Settings’ then select ‘Layer’ and under ‘Layer Settings’ select ‘Outside-in’ next to the ‘Outline Direction’.
  4. Check print platform. Check around the model and if you see that the effect is more prevalent on one side than the other, the effect could be due to calibration. If so run through the usual calibration process.
  5. Use it to your advantage. Depending on the type of model that you’re printing you can use the internal and shell printing order to your advantage. When you want a high quality print with a good surface finish where the actual strength of the model isn’t important, select print from the Outside-in. If however the strength of the print is paramount then select Print from in Inside-Out and double the wall thickness. The reason for the difference in strength is that when you print from the Outside-in you eliminate the small amount of overlap that causes the ghosting issue, but this also means that the actual structure won’t create the same strength of bond between the internal and external structure due to the lack of overlap.

3D Printing Problem Checklist: Ghosting of the Internal Structure

  • Check the shell thickness.
  • Increase the wall thickness.
  • Use Infill after perimeters.
  • Check print platform and recalibrate if necessary.
  • Use it to your advantage.

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3D Printing Problems #17: Gaps between Infill and Outer Wall

3d print problems gaps

What’s the 3D Printing Problem?

When you look at the top or bottom of the print, you can see a slight gap between the infill and the outer perimeter walls.

What’s Causing this 3D Printing Problem?

Gaps between the perimeter and top layers used to be a common problem, but as printer accuracy has improved and the support for different materials extends, it’s now less of an issue than it was.

However the new wave of advanced materials are far less forgiving than the likes of PLA and ABS, and we’re starting to see a slight resurgence of the problem.
Gaps are caused by the filament used for the infill and outer walls not quite meeting bonding and is a relatively easy fix.

The most obvious cause of the problem is that the infill overlap is not set, or it’s set to “0”. This means that the slicing software is actually telling the printer not to allow the two parts of the print to meet.

Another issue could be the order in which you have set the infill and outer perimeters to be printed. If you’re printing the perimeter first for a high quality print then there is generally little or no overlap which can again cause the problem.

3D Printer Troubleshooting: Gaps between Infill and Outer Wall

  1. Check the infill overlap. This is by far the most common issue and is really easy to resolve. In your slicing software locate the ‘Infill Overlap’ option and increase the value.
    • In Cura by default this is set to 15% so raise it to 30%.
    • In Simplify3D you’ll find the option in ‘Edit Process Settings > Infill > Outline Overlap’ again increase the value. This setting is directly linked to the extrusion width, so the % value will be a % of whatever you’re extrusion width is. When adjusting this setting always keep it below 50% or you’ll start to see the effects of the overlap in the outer perimeters of your print.
  2. Printing infill before the perimeter. If you’re printing with a relatively thin outer wall the structure of the infill can show through. If this happens then you can switch the order by which the printer lays down the infill and perimeter layers. For example, in Cura check to see if you have ‘Infill prints after perimeters’ ticked.
  3. Increase Hot end temperature. Some of the latest advanced materials such as XT-CF20 are a little less forgiving when it comes to spread due to the carbon fibres that make up part of their structure. When printing with these materials you may find that a slight 5-10º increase in hotend temperature makes all the difference.
  4. Slow it down. Okay, so you may be in a rush to get the print out, but printing at higher speeds can cause all sorts of issues if the printer isn’t perfectly calibrated. If you need to print quick you can still avoid gaps by decreasing the speed of the top layer.

3D Printing Problem Checklist: Gaps between Infill and Outer Wall

  • Check the infill overlap.
  • Printing infill before the perimeter.
  • Increase Hot end temperature.
  • Slow it down.

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3D Printing Problems #18: Non-Manifold Edges

3d print problems non manifold

What’s the 3D Printing Problem?

Parts of your print are missing or the final print is weak and falls apart despite the exterior quality of the print looking fine. Sections of the print look completely different from the print preview or the final print has geometry errors that make no sense.

What’s Causing this 3D Printing Problem?

Non-manifold edge are the common cause of misshapen or odd prints. Non-manifold edges are the edges of models that can only exist in the 3D space and not the physical world.

For example if you have two cubes in the real world and try to overlap them directly, it’s physically impossible as the solid outer walls prevent the two objects from intersecting.

In the 3D world you can simply intersect the two, they still exist as individual objects, but the software we use also enables them to intersect in the virtual world.

In order to get the two to print correctly the objects need to be merged so that any inner walls are removed and an object with a single undivided inner cavity is left.

Another common cause is if you have an object such as a cube and delete one of the surfaces. You essentially have an object with a hole, it might look like a shape with five sides, but it only exists in the virtual 3D space, this is geometry with no physical form.

Although you can see the outer walls in the software, the walls that meet the hole only have dimensions in two axis. The third dimension which we see as the thickness of the wall is only illustrative and has no real physical dimension. When it comes to slicing the model the  software does it’s best and in many cases will repair the hole, however in more complex models the effects can be interesting to say the least.

3D Printer Troubleshooting: Non-Manifold Edges

  1. Use latest slicer software. Most of the latest slicer engines all support the automatic fixing of non-manifold edges but it’s still good practice to ensure that your models are correctly formed and print ready.
  2. Fix in Horrible in Cura. In Cura open Expert Settings and make sure that under ‘Fix Horrible’ you have Combine everything (Type-A) ticked.
  3. Fix ‘Non-manifold’ in Silmplify3D. In edit ‘Process settings’ click the ‘Advanced’ tab and select ‘Heal’ next to ‘Non-manifold segments.
  4. Use the layer view. In your slicer software use the layer view to check through the model so you can see where the issues appear. A quick slide through the layers will often highlight an easy to fix problem.
  5. Use software to fix issues. One of the easiest ways to fix models with non-manifold edges is to use software; Blender and Meshmixer both have features built in that will quickly enable you to highlight problems with your models and fix them prior to slicing.
  6. Merge objects. Really it’s better to fix your 3D models prior to importing them into your slicing software. To do this, make sure that when you have two objects that do intersect or overlap you choose the appropriate Boolean function to either intersect, merge or subtract.

3D Printing Problem Checklist: Non-Manifold Edges

  • Keep your slicer software up to date.
  • “Fix Horrible” (in Cura).
  • “Fix Non-manifold” (in Simplify3D).
  • Use the layer view to check for mistakes.
  • Use software like Blender or Meshmixer to fix issues.
  • Merge objects.

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3D Printing Problems #19: Model Overhangs

3D Print Problems Overhangs

What’s the 3D Printing Problem?

You load your print into your slicing software and everything looks good. Hit print and you find that some parts of the model print absolutely fine, whilst other parts end up as a stringy mess. OK this might seem obvious and the issue of overhangs is often seen as a 3D printing rookie mistake. But it’s surprising just how often even experienced 3D printers are hit with an overhang issue.

What’s Causing this 3D Printing Problem?

The process of FFF requires that each layer is built upon another. It therefore should be obvious that if your model has a section of the print that has nothing below, then the filament will be extruded into thin air and will just end up as a stringy mess rather than an integral part of the print.

Really the slicer software should highlight that this will happen. But most slicer software will just let us go ahead and print without highlighting that the model requires some type of support structure.

3D Printer Troubleshooting: Model Overhangs

  1. Add supports. The quickest and simplest solution is to add supports. Most slicing software will enable you to do this quickly. In Simplify3D click Edit Process Settings > Support > Generate support material; you can the adjust the amount, pattern and settings. In Cura just click the Support type from the Basic settings.
  2. Create in model supports. Supports generated by software can be intrusive so creating your own in your modelling application is a good alternative. It takes a bit more skill but can enable some fantastic results.
  3. Create a support platform. When printing a figure, arms and other extrusions are the most common areas that cause problems. Using supports from the print bed can also cause issues as they often have to span quite large vertical distances; for structures that are supposed to be easily removed and fragile, this distance is prime for causing problems. Creating a solid block or wall under arms etc and then creating a smaller support between the arm and block can be a great solution.
  4. Angle the walls. If you have a shelf style overhang then an easy solution is to slope the wall at 45º so that the wall actually supports itself and removes the need for any other type of support.
  5. Break the part apart. Another way to look at the model is to break it apart and rather than print in one section make two. With some models this enables you to flip what would be an overhang and make instead make it a base. The only issue with this is that you then have to find a way of sticking the two parts back together.

3D Printing Problem Checklist: Model Overhangs

  • Add supports
  • Create in model supports
  • Create a support platform
  • Angle the walls
  • Separate the model and print smaller parts

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3D Printing Problems #20: Leaning Models

3D Print Problems

What’s the 3D Printing Problem?

As the print forms it starts to lean. Instead of being straight and true, vertical edges are printed at an angle, and this angle isn’t consistent throughout the print. The severity could be increasing and decreasing at different stages.

What’s Causing this 3D Printing Problem?

The cause of the issue is generally very simple; one of the pulleys attached to a stepper motor is slightly loose, or one of the belts is rubbing against something and stopping the full travel of the head. All you need to do to correct the issue is to make sure that none of the pulleys are slipping and the grub screws that hold the pulleys in place are all tightened.

Although this should be a quick and straightforward fix, one issue you may experience as you go to tighten the pulleys is that the small grub screws that tighten onto the shaft of the motor aren’t always that easy to access. Firstly diagnosing which pulley is causing the issue and then getting access to that pulley can be tricky and time consuming.

3D Printer Troubleshooting: Leaning Models

  1. Check X and Y axis. If your print is leaning to the left or right then you have an X axis issue. Back to front and you have a Y axis problem. Once you’ve diagnosed which it is you can then check the belts and pulleys. If you have a printer such as the PRUSA i3 then the process is pretty straight forward, as the steppers are directly connected to the main drive belt. For the Ultimaker and other printers that process can be a little more tricky.
  2. Check the belts aren’t rubbing. Look round each of the belts and ensure that they’re not rubbing against the side of the machine or any other components. Also check to see that the alignment of the belts is correct. If one is at a slight angle then this can cause issues.
  3. Tighten the stepper motor pulley grub screw. Once you diagnose which axis is causing the issue, use an Allen key to tighten the pulley grub screw that attaches to the stepper motor.
  4. Check rod pulleys. More complex machines such as the Ultimaker 2 have a series of belts and pulleys. The main X, Y rods at the top of the machine feature eight pulleys. Go round each of these on the affected axis and tighten the grub screws for each. It’s unlikely that these will cause any slip but if one is loose then a belt may misalign.

3D Printing Problem Checklist: Leaning Models

  • Check X and Y axis.
  • Check the belts aren’t rubbing.
  • Tighten the stepper motor pulley grub screw.
  • Check rod pulleys and tighten.

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3D Printing Problems #21: Misaligned Layers

3D Print Problems

What’s the 3D Printing Problem?

As the print is forming, there appears to be a few issues with the quality. Look closer and you see that the layers aren’t aligning quite as they should. As each line is being laid down neatly side-by-side, you’ll see gaping. Look at the internal support structure and again the pattern looks slightly out, and the outer wall rather than being straight has slight misalignment, causing an uneven rather than smooth face. As you rotate the model around you’ll probably find that the issue only affects the print in one direction; front to back or left to right. By the time the print gets to the top it’s all starting to look a bit messy with strings of filament and a top layer that only partially covers the top of the model.

What’s Causing this 3D Printing Problem?

Over time the parts of your 3D printer — such as nuts, bolts and belts — will become loose and require a tighten. The effect of misaligned layers is similar to the cause of the more pronounced effects of shifting layers and there is no doubt that there is a crossover. If left unchecked, this problem will eventually result in shifting layers, but as the issue starts the visual effect on the prints is far less pronounced and can look very different. The cause is usually linked directly to a loose belt.

3D Printer Troubleshooting: Misaligned Layers

  1. Check belt tension. Start by going around your printer and checking the belt tensions. Use your thumb and index finger to pinch the belts together. If the belts easily touch without putting up any resistance then they’re too loose; when you pinch you should feel a bit of slack at first and then resistance before the two belts touch.
  2. Are top and bottom belts the same? The printer belts are normally just one continuous loop hooked around two pulleys. A common issue is that over time the belt can slip on one pulley and gradually gets tighter on the top compared with the bottom — or visa versa — and again this can cause issue.
  3. Tighten the belt tensioner. If you own a printer such as the PRUSA i3 then this correction for the X or Y axis really couldn’t be easier. Just tighten the belt tensioners at the front and on the side of the machine. On an Ultimaker the two stepper motors for the X and Y axis can be loosened slightly by untightening the allen key bolts and then pushing down on the motors and re-tightened. If it’s one of the main belts then the belt has probably slipped inside the block that secures the two ends of the belt. If this is the case the block will need to be removed and adjusted before being re-fitted.

3D Printing Problem Checklist: Misaligned Layers

  • Check belt tension.
  • Are top and bottom belts the same?
  • Tighten the belt tensioner.

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3D Printing Problems #22: Extrusion Temperature Too High

3D Print Problems Too Hot

What’s the 3D Printing Problem?

Filament is surprisingly resilient to all types of mis-configuration, including overheating of the hot end. It’s for this reason of resilience that noticing your hot end is too hot isn’t always as easy as you’d think it would be. The effects can be as obvious as discoloured filament; in our sample here the dark line that appears half way up 3D Benchy is an obvious sign of scorching where the filament has burnt. This scorching can just appear as slight discolouration or darkening which is less obvious than the dark line above.

Another sign can be the appearance of uneven layers; when you take a closer look you can see that it’s not so much uneven as melted. Again our model shows this subtly on the cabin, and to a far greater effect on the chimney where it starts to look a little like wax running down a melted candle.

Overheating filament can also cause huge issues with accuracy especially when it comes to threadscrew holes. Finding that some holes are correct and others are too small is often an initial sign that the temperature may well be a little too high.

What’s Causing this 3D Printing Problem?

Normally, having too hot a hot end or overheating is an easy fix. The hot end is too hot so you need to cool it down. There needs to be a fine balance between melting the filament so that it will flow, and enabling the filament to solidify quickly so that the next layer can be applied to a solid surface. Before you go adjusting the temperature however, first make sure that you have loaded the correct material settings for your 3D printer (as part of the filament loading process). If you have, then it could be the you need to adjust the temperature just a touch.

3D Printer Troubleshooting: Extruder Temperature Too High

  1. Check the material settings. This might seem obvious, but just double check that you’ve given the printer the correct details about the material. The latest filament temperatures range from between 180 – 260ºC or thereabout, so it’s surprising how easy it is to get this wrong.
  2. Decrease the hot end temperature. In the printer or software settings decrease the hot end temperature. Depending on the severity of the overheating, drop the temperature in 5ºC intervals.
  3. Speed up the print. If the filament isn’t being discoloured then you could try speeding up the print speed.
  4. Check the fans. Check that the cooling fans are directed at the hot end. Check that they’re in the right position, and if possible boost their speed to increase airflow over the cooling filament.

3D Printing Problem Checklist: Extruder Temperature Too High

  • Check the material settings.
  • Decrease the hot end temperature.
  • Speed up the print.
  • Check the fan position.

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