How to Cold-Pull clogged nozzle
Your 3D Printer melts plastics and tries to extrude it through a very tiny hole in the Nozzle. It’s not often you end up with a clogged nozzle if you use your 3D Printer on a daily basis. Here’s how to Cold-Pull, and prevent issues by Cold-Pull clogged nozzle.
Want to see the following in a video-format instead? Check out my video here.
Identifying when you need to Cold-Pull a clogged Nozzle
The fact that your 3D Printed takes an (usually) exposed roll of plastic and drag it through tubes and gears to end up in a funnel, pushing molten plastic out of a tiny hole is a recipe for disaster. No, really. It’s very easy to get particles down the pipe and end up partially clogging your nozzle.
The best way to solve a nozzle clog it is by making a cold-pull.
A clogged nozzle can be fully and partially clogged. A partially clogged nozzle will sometimes make your drive gear to skip steps and dig into the filament, as if you had too much pressure. But a partial clog will almost always curl your filament around the nozzle when extruding filament over the print bed.
A fully clogged nozzle can be identified when you cant extrude filament and you can’t manually push filament down and out of a hot extruder.
Clogging a nozzle can also happen when you use filaments of different brands, colors and types all the time. Some of them tend to leave a bit of residue that other plastic types might not bond and melt with. You end up with a hard part that clogs your nozzle.
Replacing a nozzle all the time is expensive and time-consuming, not to mention the fact that you could end up snapping wires and need to re-calibrate the build plate.
Performing a hot-pull (faster than cold-pull)
I recommend doing a “hot-pull” before a full cold-pull since it’s less stressful for the mechanics in your 3D Printer.
I’ll guide you through that procedure first, if it fails, We’ll move over to Cold-Pull.
Step 1
Unload your filament and make sure you have good access to you hotend.
For bowden typ extruders, this might mean that you need to unplug the guide-tube.
Step 2
Heat the nozzle to around 200-220C.
Make sure you start of cold, and as low as 190C for PLA-only 3D printers.
Step 3
Insert a piece of white/bright nylon or a strong filament.
Push it down for 5-15 seconds or until you push filament out of the partially clogged nozzle.
Step 4
Pull back the filament out of the hot end and inspect the semi-molten end.
This should have some dirt and gunk on it. Usually some black dots and filament.
Step 5
Cut away the dirty part of the filament and repeat from step 3 until your filament comes out clean.
After around 5-20 repetitions you should now have a unclogged nozzle.
Please note that sometimes this isn’t enough, and we have to do a severe cold pull, that puts more stress on the printer.
The Cold-pull helps clean harder particles lodged and the end of the extruder.
To do a full cold-pull procedure, follow these steps instead:
Step 1.
Make sure you have good access to you hot-end. For bowden typ extruders, this might mean that you need to unplug the guide-tube.
Step 2.
Heat the nozzle to around 240-260C. If you’ve only printed with PLA, go to 220C.
Step 3.
Insert a piece of white/bright nylon or a strong filament. Push it down as hard as possible (by hand). Is there filament coming out? then stop.
Step 4.
Stop the heater and let the printer cool down to around 90C for PLA and 160C for ABS. Try to keep pressure on the filament during cooldown.
Step 4.5,
When the printer reaches the colder temperature mentioned in step 4, Pull back the filament quick and hard out of the hot end and inspect the semi-molten end. This should have some dirt and gunk on it. Usually some black dots and filament.
Step 5.
Cut away the dirty part of the filament and repeat from step 2 until your filament comes out clean and you can feed filament without it curling up on the sides.
You are now free of clogs! Congratulations!
3D Printer keeps clogging!
If your nozzle keeps clogging you may want to take a few precautions.
Firstly I recommend you use some sort of filament-dust-filter to avoid getting particles down the hot end.
This filter I made can be printed quickly and mounted without having to unload filament. Just cut off 2 small pieces of kitchen sponge and put them inside, so the filament have some friction. Mount the filter before the extruder.
The fastest and simples filter to print is this one, but it requires you to unload filament to mount.
Bad nozzle and filament
You might also just have a low quality nozzle that isn’t bored well (or worn out from abrasives) You could also upgrade to a larger nozzle diameter which drastically reduces risk of clogs, and gain tons of other benefits.
And lastly, use filament that don’t have particles in it. That means no self-illuminating, no wood/metal-fill or carbon-filled filaments. These are all abrasive and will wear the nozzle down faster.
Check out this guide to better understand what nozzle you have and could get.
Don’t forget to share this guide to help your friends out!
