How to: Cleaning clogged nozzles

Introduction

3D printers are great tools for creating custom objects, but they can be finicky. One of the most common problems that 3D printer users encounter is a clogged nozzle. A clogged nozzle can prevent the printer from extruding filament properly, which can lead to poor print quality or even failed prints. However, cleaning clogged nozzles is relatively simple.

Causes of Clogged Nozzles

There are a number of things that can cause a 3D printer nozzle to clog. Some of the most common causes include:

• Using the wrong type of filament. Some filaments are more prone to clogging than others.
• Printing at too high of a temperature. This can cause the filament to melt and solidify inside the nozzle, blocking the flow.
• Printing with a dirty nozzle. Over time, the nozzle can build up with dirt and debris, which can block the flow of filament.

Methods for cleaning clogged nozzles

There are a several different ways to clean a clogged nozzle. The best method for you will depend on the severity of the clog and the type of filament you are using. For the pull methods, I typically try to use a white PLA or better natural nylon so it is easy to see if anything was pulled from the nozzle.

Method 1: Standard Pull to clean a clogged nozzle

A standard pull is the quickest way of cleaning clogged nozzles. To perform a standard pull, you will need to:

1. Heat up the nozzle to at least 180°C
2. Remove the filament from your printer
3. If you have a Bowden, remove the PTFE so you can push directly into the heater block
4. Insert a piece of filament into the nozzle and push it through until it comes out the other end of heater block
5. Pull filament out quickly
6. Examine the blob at the end of your piece of filament, if it appears to have schmutz in the blob, cut it off and repeat #4-6
7. Once the filament is coming out clear, you should be ready to reassemble your print head, reinsert your filament and resume printing

Method 2: Cold Pull

If you are still having issues after cleaning clogged nozzles in method 1 you can try a cold pull. A cold pull is similar to the standard pull, but is intended to allow the blob to partially harden around any debris in the nozzle. To perform a cold pull, you will need to:

1. Heat up the nozzle to at least 180°C
2. Remove the filament from your printer
3. If you have a Bowden, remove the PTFE so you can push directly into the heater block
4. Insert a piece of filament into the nozzle and push it through until it comes out the other end of heater block
5. Lower temperature of nozzle to somewhere between 125°C and 140°C
6. Pull filament out quickly
7. Examine the blob at the end of your piece of filament, if it appears to have schmutz in the blob, cut it off, reheat the nozzle to at least 180°C and repeat #4-7
8. Once the filament is coming out clear, you should be ready to reassemble your print head, reinsert your filament and resume printing

Method 3: Needle Cleaning

If the cold pull method does not work, you can try using an needle to clean the nozzle. A small gauge sewing needle can work or you can purchase a kit like the one to the right. Once you have an appropriately sized needle you need to:

1. Heat up the nozzle to at least 180°C
   (I usually go to 250°C for this on printers that can handle it)
2. Insert a needle into the nozzle and gently scrape the inside of the nozzle
3. After I have scraped the inside of the nozzle I usually go back and do a standard or cold pull to get anything that was knocked loose by this method
4. You can also just try printing again

Method 4: Drill Bit

If needle cleaning did not work, you can also try using a drill bit to clean the nozzle. WARNING: if you use a drill bit that is too large it can damage your nozzle, so I recommend purchasing a kit like the one on the right. If you have an appropriate sized drill bit you need to:

1. Heat up the nozzle to at least 180°C (I usually go hotter for this method as well)
2. Insert drill bit into the nozzle and gently spin the bit inside of the nozzle, the goal is to use the bit like an auger to pull anything in the tip of the nozzle out
3. After I have augured out the inside of the nozzle I usually go back and do a standard or cold pull
4. You can also just try printing again

Method 5: Disassembling the Nozzle

If the nozzle is still clogged, you may need to disassemble the nozzle to clean it. To do this, you will need to:

1. Remove the heater block from the printer
2. Remove the nozzle from the heater block
3. Clean the nozzle with a wire brush, tweezers, a needle or a drill bit
4. Reassemble the nozzle and heater block
5. Heat up the nozzle again and resume printing

Alternatively, if you have another clean nozzle of the appropriate size you can replace it at this point

Method 6: Cooking the nozzle

If you had to disassemble the nozzle, and you don’t have a spare, or if you swapped out for a clean nozzle, you can try cleaning the nozzle in your oven. You will need something you can place the nozzle on that can withstand the heat of your oven, but that you will not use for food after you are done. I usually collect multiple nozzles that need to be cleaned and then use a fire brick.

1. Put fire brick in oven on middle rack
2. Place nozzles tip up on fire brick
3. Heat oven to higher than your normal operating temperature, the goal is to heat plastic until it flows out of nozzle. I usually go for 500°F or 260°C
4. Leave nozzles in oven for 20-30 minutes, or until you see a small puddle of filament that oozed out onto the fire brick
5. If you don’t see that any filament has oozed out of the nozzle you can try increasing the oven temperature and going back to #4
6. Remove nozzles one at a time from the oven with needle nose pliers and clean surface with a wire brush for that like new appearance

Conclusion

Most methods for cleaning a clogged nozzle are relatively simple, but it is important to do it correctly to avoid damaging the nozzle. By following the methods outlined above, you can easily clean your nozzle and keep your 3D printer printing smoothly.