Filament Jam Troubleshooting

Have you tried unloading and reloading the filament?

Pull the filament out, cut the end off, and reinsert it. Same principle as rebooting a computer. If it is a one-time problem, this is all you need to do. This will also help us determine how bad the jam is. If the filament still doesn't flow after reinserting, then more aggressive steps will need to be taken.

Did you cut a point on the end of the filament?

Cutting a point on the end helps the filament slide past any edges inside the hot end while it is being inserted. Filament with a square end will often catch on something when being put in. If the customer did not do this, then they may have trouble putting the filament in and believe the printer is broken, or they might not realize the filament is not in all the way and will think that the printer is jammed.

Is the nozzle too close to the bed?

If so, it will prevent the plastic from coming out.

How fast are you printing?

Sometimes a jam is not a jam at all. It is just that the user is pushing the printer or the material beyond its capability. If this is the case, then you will most likely see under extrusion during the parts of the print when the machine is moving the fastest (i.e. infill as opposed to perimeters). See this article on how to get good flow by understanding the relationship between temperature and speed.

What kind of filament is it?

Different types of filament are more prone to certain issues than others. For instance, PLA is especially prone to heat creep. Flexible materials are also prone to binding up inside the feeder.

What color is it?

The pigments used in a material can affect how it prints. Most plastics are naturally translucent or semi-translucent, so the solid (opaque) colors require the most pigment. White and other light colors use titanium dioxide pigment, which has a noticeable effect on the thermal properties of the plastic. This means that you may need to print them slightly hotter and they may be more prone to heat creep.

Does it jam with different materials?

This will help us determine if it is a filament related issue or a printer issue.

Does it jam with different colors or brands?

This will help us determine if it is possibly defective filament.

What temperature are you printing at?

Make sure that they are using the correct temperature for their material. Too low and the plastic will remain viscous and not flow easily. Too hot and the material will carbonize (burn) and clog the nozzle. Encourage the customer to experiment with different temperatures. Try adjusting it in 5° increments. Every printer and every spool of filament is different. 200 °C on one printer may not be the same as 200 °C on another printer, even if they are identical make and models. Each material has a range of temperatures that it is ok to print at. The ideal temperature is somewhere within that range.

What kind of printer do you have?

Make sure that the customer is using the correct type of filament for their machine. It seems obvious, but sometimes people will try to run 3 mm filament in a 1.75 mm printer, or vice versa. A more subtle issue is that some "3 mm" printers require 2.85 mm filament. Not all "3 mm" filament is manufactured to this spec.

If they are trying to print flexible materials, make sure that their printer is actually capable of doing it. See this general article on filament compatibility.

When you pull the filament out after it jams, what does the end look like? Is there a bulb?

If there is no problem then the filament should be straight, with a rounded end and possibly a string of melted material. If the filament has a bulb on the end, then that is a definite sign of heat creep. A bulb is a length of expanded filament, typically 5 to 10 mm long.

Is the heatsink fan running?

The heatsink fan (not to be confused with the layer cooling fan) is critical for the operation of an all-metal hot end. Without proper cooling, heat creep will occur very quickly. On most printers, the fan turns on after the temperature goes above 50 °C, although on some printers it runs continuously. Even if the fan is running it may not be providing sufficient cooling. The fan might have a problem and not be operating at full speed. There also may be something obstructing the airflow, or the heat sink fins may be dirty.

Does the filament flow when you push it through by hand?

Have the customer release the tension on their feeder and then push the filament by hand. If the filament is easy to push, then that indicates an issue with the feeder. If not, then there is something going on down at the hot end.

Does it jam immediately when starting a print, or partway through?

This helps us gauge how bad a jam is. If it is happening halfway through a print (after it has been going for several layers or more) then that is an indication of heat creep. If it jams on the first or second layer, then there is a more fundamental problem. If no filament comes out at all, then there is a blockage in the nozzle.

Is the motor turning and grinding down the filament, or is it not turning and making a clicking noise?

If the motor does not have the strength to push the filament, then it will turn a little bit then jump back and make a clicking noise. This may be an indication that the motor is having an issue, but only if the filament flows easily otherwise.

What is your feeder tension?

If their feeder has a tension adjustment, some people crank it down too tight. The motor cannot overcome the extra force. 

What is your retract distance?

Retracting too far will pull molten material up into the cold zone. The molten material can then harden and cause a jam. This can happen especially during parts of the print with many repeated retractions. The maximum retraction distance depends on what hot end they have, but it is typically about 4 mm.

What is your nozzle diameter?

If they have installed a small nozzle then that may be causing problems, especially if they are using filaments infused with other materials. Like metal, wood, or carbon fiber fills.

What is your layer thickness?

Very thin layers are the same as having the nozzle too close to the bed. It causes more back pressure and prevents the plastic from coming out.

Is their printer using any known defective parts?

Check if there are any known issues with their printer, feeder, or hot end.

How far down can you insert the filament?

If there is a complete blockage then this will tell you how far down the blockage is. Whether it is all the way down in the nozzle or farther up in the heat break or heat sink.

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