5 Common 3D Printing Problems and How to Fix Them

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There’s nothing worse than the sinking feeling you get from checking a two-day-old print to find a bed of 3D printed spaghetti. This has happened to me more times than I care to admit, but it’s not always a schoolboy mistake. Users can search for the best slicer settings for their printer and filament, but sometimes a setting gets missed and that Spider-Man bust that looked cool and easy for beginners to print on Printables looks more like Carnage after a bad night out.

FDM 3D printing is now more accessible than ever, and newcomers to the hobby can avoid the dark days of self-leveling a print bed. Current 3D printer models are nearly automated, but that doesn’t mean things can’t go wrong. I’ve identified five of the most common 3D printing problems I’ve encountered in my five years in the business, and each can be solved with a little setup, preparation, and maintenance know-how. They mainly depend on how the filament is extruded from the heated nozzle and how the first layers bond to the plate. Most free libraries of community-created STL files, such as Thingiverse, Printables, and MakerWorld, are projects that have been tried and tested, which usually means that 3D printing issues come from one of the fixes below.

Cobwebs on a 3D print are not from a resident spider trying to help. These thin trails of plastic that stretch between 3D printed surfaces come from the filament oozing from the printing nozzle as it moves from one surface to another. This can be caused by several factors, most commonly an overheated nozzle, low or no filament retraction settings, or wet filament.

You can correct the first two in the slicer before starting a project, although some printers allow adjustments during printing. First, check the recommended filament temperature and adjust it accordingly. If the nozzle is set to the lowest temperature provided, simply turn it down a degree or two and print a small test to check the results. Next, check the retraction settings; if they are off or too low, increase them little by little and test until the stringing stops.

A wet or damp filament may not feel wet to the touch, but filaments like PLA are porous and can absorb moisture from the surrounding air. You have two options, the most obvious being to store the filament in a dry environment at room temperature. This is easier said than done for people with a 3D printer in a workshop, for example, so buying a filament dryer and dispenser from a solid brand like Sunlu is a great way to combat this problem. Also store the filament in its vacuum packaging until ready for use.

I dragged some projects onto a print bed on the third day, so don’t be like me and try to print a Stormtrooper helmet without properly preparing. Poor adhesion to the print bed occurs when the filament fails to bond to the build plate, causing the print to warp, lift, or come loose while printing. This usually happens because of a dirty or oily build plate, unleveled bed, poor Z offset, wrong bed temperature, or printing the first layer too quickly. This is one of the main reasons why 3D printer projects fail.

The best thing to do before each print is to wipe the build plate with a microfiber cloth and isopropyl alcohol. I like to examine my print bed with my Olight ArkPro Ultra, using its torch and UV light modes to check that there is absolutely nothing on the build plate after cleaning. Next, I apply a light coat of filament adhesive; In my experience, Elegoo glue sticks work very well.

Most modern 3D printers feature automatic bed leveling and Z-offset to ensure the print head doesn’t scratch the filament. Older 3D printers require manual procedures for leveling and clearing with a piece of paper. Next, make sure the print bed is at the right temperature for the filament to stick; find it on the manufacturer’s website. Use the filament manufacturer’s advice rather than the printer brand, as these figures may differ. Finally, slow down the printing speed of the first layer; the slower the better for maximum grip.

Notice corners appearing at the bottom of a 3D printing project? This is usually a temperature or environmental issue caused by uneven cooling of the plastic, which can damage the bottom of the print and even reduce adhesion. Temperature control is very important in 3D printing, as temperature differences between layers and blanks can cause excess plastic to shrink. This isn’t a big problem with PLA, which is what I usually use for my handcrafted collectibles, but ABS can be a big problem.

A simple solution is to place the 3D printer in an enclosure, which helps trap and control ambient heat while blocking drafts and other external interference. Also check if the temperature of your bed matches the material you are using. When cutting projects, be sure to enter the correct filament type and update automatic settings if applicable.

Another practical solution is to add an edge or raft for parts with small contact areas, with natural supports being an absolute necessity. A good rule of thumb that I follow with FDM 3D printing is: if not in use, print in PLA; it’s much more user-friendly and perfect for anything that won’t be physically used.

Underextrusion occurs when the 3D printer’s extruder does not push enough filament to fill gaps or create a complete layer. In my experience, this causes weak walls, gaps between layers, and pieces that break with little force. Again, this can be caused by several factors: a clogged or stuck hot nozzle, incorrect filament diameter settings on the slicer side, a bad extrusion multiplier, or worn or slipping extruder gear.

In my experience on the Elegoo, Snapmaker, and Prusa 3D printers, the most common problem is a hot end nozzle blockage. Turn off the 3D printer and allow the nozzle to cool, then follow the manufacturer’s instructions to remove it and check for blockages. I’ve always found a handheld screwdriver model to be ideal for penetrating and removing blockages. For annoying blockages near the nozzle opening, an airbrush cleaning tool is ideal for loosening and cleaning.

While the hot end nozzle is unscrewed, it is a good idea to check that the feed channel and gear are not blocked. A good way to tell if the filament is jumping instead of being grabbed and pushed into the extruder is to check the discharged filament for excessive vertical wear. If so, the gear will likely need to be replaced or tightened. Then make sure the slicer has the correct filament settings; if they are turned off, no one will get a finished print.

For finished prints that look more like a set of scales than a clean product, there is most likely a mechanical defect. This happens when layers suddenly move sideways in the middle of the print, usually due to loose or slipping belts, axis problems, or the printhead colliding with a lifted part, as mentioned earlier.

First, check the belt tension: it should be tight but still move slightly under pressure (check the printer’s instruction manual before trying so it doesn’t break). Next, check that the gantry and print head are moving freely using the on-screen printer controls and apply a little lubricant if necessary. This should have come with the 3D printer.

After that my advice is to level the print bed, sort the Z axis and make sure the print bed is clean with a small amount of adhesive applied. Printing consecutive, successful 3D prints is often a matter of repetition and patience. Personally, I upgrade my Prusa XL and Elegoo Centauri Carbon 2 before each print to be on the safe side. This is a longer process, but the slower overall project time also means fewer failures and better results.