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How do I fix a clogged or jammed nozzle?

When working with any 3D printer, it's normal to run into occasional issues with clogged or blocked nozzles. 

Most 3D printers are equipped with swappable nozzles to make replacement as easy as possible when a nozzle wears out or can't be un-clogged.

You may have a jam or clog if plastic isn't coming out of the nozzle, or the drive gear on the extruder is 'chewing' small divots into the filament rather than pushing it through to the extruder.

There are a few possible explanations, including a worn nozzle, expired or defective filament, environmental factors, or even software settings.

Below we'll cover a few details about the causes, and some possible solutions to these problems.

 

Two kinds of blockage:

1. Jams

If your printer loads and unloads filament normally, and is able to extrude plastic when the nozzle is in the air, but on the first layer of a print nothing (or very little) comes out and you hear a “skipping” or grinding sound from the extruder motor, this likely means that your first layer is set too low.

When the nozzle is pressed too close to the bed to allow plastic to escape, the machine will behave as if clogged. – See Section 6 (First layer height) for steps to adjust this setting on your machine or in the software.

2. Clogs:

Clogs are far more common than jams. If your printer isn’t able to extrude filament even when the nozzle isn’t touching the bed, it most likely has a nozzle clog. These are usually made up of dust and/or plastic debris which can accumulate in the nozzle over time.

Caution:

Some online guides for clogs recommend using a guitar string or sewing needle through the bottom of the nozzle to “break up” the clog – while this may work in the short term, it's likely to deform the nozzle tip or leave scratches in the internal teflon sleeve, making future clogs and problems more frequent.

Guides may also direct you to use a heat gun or blowtorch on your nozzle – do not do this - Cubicon nozzles contain a teflon sheathe which will burn under a flame and release hazardous fumes.

 

Steps for fixing a clogged nozzle:

1. Cleaning the nozzle

Even in ideal conditions, the nozzle on a printer is likely to acquire some buildup of plastic over time. The brass brush in your printer toolkit can sometimes clear a jam if the problem is at or near the very bottom of the nozzle.

With the nozzle still attached, pre-heat your extruder to the temperature you've been printing at, then use the brass (not plastic) part of the included brush to scrub away any visible buildup. 

2. Push Through

Some clogs can be solved by simply applying a little more muscle than the extruder motor can produce, forcibly pushing out the problematic section.
  • a. Pre-heat your nozzle to ten degrees above the highest temperature listed for the filament that caused the clog.

  • b. With the nozzle pre-heated, try to manually push filament into the machine while holding down the release clip for your extruder - it's a black paddle sticking out of the left side of the extruder.
    • Pushing the filament by hand should have some resistance but be fairly spongey, with a consistent amount of force applied there should be a steady flow of plastic coming out of the nozzle.

Any popping sounds or start/stop jerky movements are a good indicator that your nozzle has acquired some air pockets, moisture, or bits of burnt plastic. You may need to continue pushing filament through, or escalate to using a plunger or a “cold pull” technique.

3. Plunger

If a clog can’t be easily pushed through by hand, our next step is to use the T-handle plunger included with the printer’s tool kit to try to force the clog through.
  • a. First we need to detach the Bowden filament tube from the top of your extruder. On the Single Plus, this is simply a friction fit, and you can pull it out and put it back in as needed. On other models, there’s a small fitting like this one:

    • If there is one, pull the plastic collet clip (usually blue) off of the fitting to unlock it, then press down on the black plastic collar while pulling the Bowden tube up and away from the print head. Be sure the hand pressing down on the ring is firm, as we don’t want to apply much force to the extruder.

    • (To reattach the tube when finished, simply push it back in until it stops. If there was one, put the plastic retaining clip back on to lock it.)

  • b. Preheat the printer to about ten degrees higher than the max temperature listed for the material in the clog. and unload or pull the filament out by hand.

    • Hold down the release tab for your extruder (circled in blue below) while performing the next step to avoid damaging the drive gear with the metal plunger.

  • c. Holding the release lever, use the T-handle plunger and insert the small round end into the fitting at the top of the extruder. Support the extruder with your free hand and try to push the clog through.

    • If you feel elastic resistance you can keep pushing. If you reach a solid obstruction you are most likely at the bottom and should stop here to avoid damaging anything with the plunger.

    • Plastic should begin to flow out the bottom of the nozzle after a few plunges. If it doesn’t, our next step is to try a cold pull.

4. Cold Pull

The cold-pull technique is an intermediate technique for clearing very stubborn clogs, and does carry some risk of causing additional damage to the nozzle, as the internal PTFE sleeve can come out along with the clog. 

It should only be used if the clog is not cleared by the previous steps and the nozzle would otherwise be discarded.

The aim is to bring the clogged section up to melting temperature then bond a new piece of filament into it, effectively grabbing the blockage. Then, we let it cool down halfway (to around 110 degrees for PLA) and gently pull the filament out by hand – hopefully bringing the problem section out with it.

Step by step cold-pull instructions:
  1. If not already removed, we first need to detach the Bowden filament tube from the top of the extruder. (See Step 3. Plunger above for instructions.)

  2. Our next step is to cut a small (6-10 inch) piece of scrap filament off of the roll of filament, with as flat an end as possible. This will function as our grabber.

  3. Preheat your extruder to the high end of the recommended temperature for whichever filament you believe caused the clog.

  4. Insert the filament as deep as possible, pressing firmly. 

  5. Allow the extruder to cool to around 30 to 40 degrees below the lowest temperature recommended for the filament.

  6. Holding the release paddle, slowly pull the filament out of the top of the extruder. With any luck, the blockage should come too.

  7. You may need to repeat this process a few times to clear the entire blockage.

Specialty cleaning filaments are sold by some manufacturers which are more easily able to grab onto the clogging material – these can be helpful but are not essential, and sometimes require temperatures too hot for normal PLA filaments.

5. Replace the nozzle

If none of the steps so far have resolved the clog, it may be worth replacing the nozzle altogether. Our printers ship with an extra nozzle, and additional nozzles are available from our website at https://www.inksmith.ca/collections/3d-printer-parts/products/single-plus-nozzle.

To replace the nozzle, bring the extruder up to printing temperature and carefully use the screwdriver-handled nozzle tool to unscew the current nozzle and replace it with the new one.

Be careful not to burn yourself on the old or new nozzle, and set any hot nozzle aside somewhere safe to cool.

Make sure to tighten the new nozzle fully into place, as a loose nozzle can cause problems later on.

Please note that the original Cubicon Single Plus (310F) does not have a replaceable nozzle, and should not be removed - however, if the extruder has a small sticker that reads "Single Plus 320/321" then it is a "320C" extruder and is compatible with these replacement nozzles.

6. First Layer Height

On many printers, users can change the z-axis offset of the first layer, effectively starting the print a little higher than ‘zero’ to compensate for any changes in bed shape.

Use this offset if your first layer is barely able to push out any plastic at all, or grinds against the surface of the bed.

For a Style Plus or MakerForge, use the control panel on the printer itself.

  1. Navigate to Settings and scroll down the touchscreen until you see 'Z Offset'

  2. Once in the Z-Offset menu (below) Select all and increase all Z layer heights by 10µm, the lowest amount.

  3. If the situation improves but the first layer is still slightly squashed and deformed (known as elephant's foot), you can bump it up again.

    Be aware that increasing this setting too high may cause prints to be more likely to detach from the bed mid-print. If this occurs, dial it back again to find the sweet spot.

7. Call for Backup

If after completing steps 1-6 in this guide the printer is still unable to extrude filament properly, it may be time to open a tech-support ticket for more specific help.

To do this, go to https://www.inksmith.ca/pages/tech-support and fill out the form halfway down the page.

The more information you can provide for your ticket, the faster our team can provide relevant help for your specific situation.

We’ll need the serial number of the machine, a brief description of the problem, and any photos or videos you’re able to share. Any more information, descriptions or photos of the problem (or things you’ve already tried) can also help us give the most applicable advice we can and get you back up and printing as soon as possible.

 

Extra Credit: Addressing the Root Cause

While occasional clogs are inevitable on even the highest-end FDM printers using new premium filaments, if you’re getting them often (especially with a new nozzle) it’s worth investigating the root cause.

There are a few common causes of frequent clogs:

  1. Worn nozzle.

    The nozzles on any 3D printer have a limited lifespan, which varies greatly based on the materials being printed, distance to printhead, and other factors. A brass nozzle in particular will need to be changed now and again as the nozzle wears out.  

    Signs of a worn-out nozzle include over- or under-extrusion, frequent clogs, or uneven wall thicknesses on finished parts.

  2. Wet, dusty, or old filament.

    Filament that has been left open for weeks or months in a humid area will generally pick up moisture from the environment. These tiny pockets of water cause small bubbling irregularities in the nozzle as the water boils and "pops," and can prevent the filament from heating evenly.

    Many users opt for specialized filament dryers (Including the eSun eBox dryer offered by InkSmith) which can sometimes rehabilitate a roll that has already had this happen, but the expansion and contraction of the process can cause the spool to bind up more tightly and give you trouble down the line.

    Filament dryers are much better at keeping a roll of filament at its best than they
    are at repairing already-spoiled spools.

     

    Filament storage tips:

    Whenever possible, it’s best to avoid letting filament get moist or dusty in the first place – this can be done by keeping it inside a filament dryer, or by sealing opened filament back up in a Ziploc/freezer bag, ideally with a silica gel pack, until you're ready to use it.

    Filament left exposed to sunlight will become brittle over time, and you may find that it causes clogs if the plastic snaps mid-print (often on a "retraction" move)

    Spools stored in the open air can often have a layer of dust build up on the roll of filament, causing small clogs or “stones” to form in the nozzle as the dust mixes with melted plastic.

  3. Defective filament

    There are many suppliers for 3D-printer filament, and not all of them are 100% reliable. Beware of suspiciously cheap or ‘clearance’ filament - especially from unfamiliar suppliers, as these can often be made in a facility with inadequate environmental controls or quality assurance.

    Budget filament can end up costing more value in time than the money saved on the purchase.

  4. Strange/novelty filament

    Similarly, there are endless different varieties of filament, some more useful and reliable than others.

    Some examples of filament which are notorious for causing clogs or damaging nozzles are:

    1. Very flexible filaments (such as TPU or NinjaFlex)
    2. Glow-in-the-dark filaments
    3. “Wood grain” filaments
    4. Carbon fiber filaments
    5. Thermochromic or UV reactive filaments
    6. Scented filaments

  5. Wrong temperature

    Refer to the packaging or product website for any filament you are using, and ensure that you aren't overheating or underheating it. A safe place to start is right in the middle of the temperature range listed, and you can adjust from there.