Nozzle cleaning tool

by whpthomas, published

Nozzle cleaning tool by whpthomas Mar 3, 2013
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This is a toothpick holder designed to make cleaning your Replicator 2 extruder nozzle, quick and effective. With the extruder drive assembly removed and the nozzle pre-heated, you insert trimmed toothpicks into the top of the hot end with a circular downward motion. Repeat the process to clear out any burnt PLA until the toothpicks come out clean. Then use a sanded down pin to clean out the 0.4mm nozzle tip. The whole process takes about 15 minutes.

This toothpick holder was designed using an ACIS solid in Shark FX/ViaCAD (vc3 file included) so will behave well with Makerware, ReplicatorG and skeinforge.


Print, insert toothpick, pre-heat, push down and twist to clean.


After about 600 hours of printing, my Replicator 2’s extruder nozzle became clogged with burnt PLA. Some of the telltale symptoms included the extruded filament curling up as it leaves the hot end, the extruder clicking as it strains to push PLA out of the clogged nozzle, and of course the inevitable print failures that follow. So I was interested in finding an easy method for cleaning a clogged nozzle that was quick, effective and inexpensive.

Some people have suggested removing the nozzle and heating it with a propane torch or heat gun to burn off the toasted plastic. However this involved disassembling the extruder, which requires additional tools, along with owning a propane torch or heat gun, and a suitable place to use it.

I had previously tried using wooden skewers, but they were too large, and splitting and sanding them to fit was time-consuming. Then Enginwiz on the Google Makerbot operators group suggested using tooth picks. These turn out to be around 1.75mm in diameter so with just a simple snip of the point they can be prepared and used very quickly to achieve great results. However the only problem is they are a little too short, making it difficult to handle them. So I decided to design this toothpick holder for nozzle cleaning to simplify this process.


I printed the toothpick holder using my 100 micron profile http://www.thingiverse.com/thing:39050 with the following settings in print-o-matic:

Infill 100%
Layer Height 0.1mm
Number of shells 0
Feedrate 80 mm/s
Travel Feedrate 150 mm/s


You need to purchase a packet of 1.75mm diameter toothpicks from your local supermarket. The first packet I purchased ranged from 1.7mm to 1.8mm – so I suspect these are quite a standard sizes. To prepare the toothpicks, cut just below the shoulder of the tip at 45°. The wooden tip will then deform into the nozzle tip and act as a scraper, to help scrape off carbon deposits.

You will also need a fine pin or needle, a course 120 grit sanding block and a pair of digital calipers. Basically, sand one end of the needle until it is 0.4mm in diameter, using the digital calipers to check as you go. You want to use course sandpaper so the end of the needle is rough enough to work like a file to remove carbon deposits from the tip. You can also use a pair of needle nose pliers to snap off the tip so you don't have to worry about jabbing yourself with it.


Start by removing the extruder drive assembly.

1) Unload the filament form your extruder and wait for it to cool down. Wait until the heat-sink fan stops spinning.

2) Turn off the power to your Replicator 2.

3) Unplug the stepper motor and unscrew the two stainless steel hex head cap screws on the front of the heat-sink fan using the second biggest hex wrench provided. This will allow the extruder stepper motor and drive assembly to be removed.

4) Now turn your Replicator 2 back on and pre-heat the nozzle to 230c.

5) Insert a trimmed toothpick into the holder. Insert the holder in through the top of the extruder so the trimmed end of the toothpick is inserted into the top of the hot end. Push down with a twisting motion to expel the burnt PLA. Repeat this step until the toothpicks come out clean.

6) Insert the sanded down pin or needle into the nozzle tip from the bottom. Then, repeat step 5 with the toothpick holder to clear any burnt PLA that may have been pushed up by the pin.

At this point you should be able to see through the clear nozzle hole by looking down into the hot-end from the top.

7) Reassemble the extruder drive assembly by re-positioning the assembly on the back of the extruder and mating it with the two stainless steel hex head cap screws. Gradually tighten using finger pressure, making sure not to cross thread. They just need to be snug, so don't over tighten them.

8) Reload your filament and let it run through for about 20 seconds. It should be coming out nice and straight.

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Comments deleted.

You have a wrong link to toothpick holder http://www.thingiverse.com/thing:39050

Surface Finish Calibration Test Shape

do you still use the technic after 3 years?
thanks for the share

This is a nice tool to build.
Usually, I rip off the cotton from one side of a Q-tip and insert a toothpick in the central hole of the plastic tube... It has worked wonders for me, but is not as sexy as a printed tool ;)
Nice work!

Henry you are a genius!!!
Your tool has always solved the problem when we have faulty layers.

Thank you very much!

Worked a few times until it broke in my extruder :) i got it out with another tooth pick :) Great idea!

Just had my nozzle clogged yesterday.... Thanks for this detailed article Whpthomas :)

Would like to share that Acupuncture needles works pretty well to unclog from the exit hole of the nozzle.
Found this at the Chinese Medical Hall. The diameter is 0.25mm

Also used aluminium wire that are used in beading (art and crafts) to clear the clog from the entry point. Cheers!

Thank you very, very much Henry. This hint and tool really saved my day and relieved me from pain with my Replicator 2. I really do not understand why MakerBot does not provide such a cleaning tool!

Have Fun Creating!

This "Thing" and the above instructions have been a HUGE help to me! It's part of a routine when I change filaments between large (50+ hour) prints

I did this similarly by stripping down some twisted copper wire and spinning it around inside the nozzle top while hot, then using a single strand to clean the nozzle tip and it seems to have worked well.

Rather than using the carbide cutters to clean the nozzle, I use 28swg nichrome wire. Carbide cutters are brittle and snap too easily. The 28swg wire can be held in a pin chuck. Something else I bought was a pack of 0.4mm HSS drills.

nice to see someone else using shark. :)