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Monday, October 29, 2012

How to clean the hotend and nozzle from the outside

How to remove clogged/molten filament in a V2 head?

Obviously you can disassemble the end, which is quite painful. It may also damage some items and threads in the long term.

Or you try whatever comes under you hand to remove the damn molten stuff in and around the PEEK. Of course, start by removing your bowden tube from the top quick coupling.

You know you are good when you can see through the nozzle. You may find it easier with a small led torch or a tilted mirror with a strong light (viewing from above). Still, it may not be sufficient because some dirt may be left aside and pushed downwards on the next print, clogging the nozzle again.

Finally, you may want to try improving your head setup, such as with the blind rivet nut.

The standard hex screwdriver

Weird, isn't it ?
The first dump tool I used was the long M3 hex screwdriver that comes with the Ultimaker...

One nice thing however is that if you leave it in place, it will transfer heat upwards in the short bowden tube, getting into contact with the solidified plastic plug. With chance, the plastic will meld again and ooze out to the head. This usually is just a temporary fix, unless you manage to remove all the plastic around to top of the PEEK.

It is somehow dangerous because that's how I created plugs also... when you remove the screwdriver, you drag some molten plastic upwards, and if it fails to exit through the top quick connector and detach itself in the short bowden, then you usually have a bigger problem than in the first place. But removing it quickly also will leave plastic behind...

So here are some other tools I use...

Push the plastic down through the PEEK with a nail!

I found a nail with appropriate size (about 88 x 3.8 mm) and polished its end cleanly

No need to remove the coupling as here
I use it to push the remaining plastic out of the nozzle in an attempt to clean it up completely, especially at the end of my day, and even more when I printed wood (as it just wants to stay in your head!)

It works best when I leave it in place for a while, so that it gets hot enough to melt the plastic around the PEEK (will not work as much as with the screwdriver). Removing it also removes part of the plastic. I've checked that it did not go through the PEEK section, may be I could try to make the end thinner, so that I could push further up to the nozzle.

Unclog the nozzle with a thin wire

Once most of the pastic is removed by any of the other methods, I sometimes use a thin electronic wire, or the leads of an electronic component, to move dirt or hard particles out of the nozzle by inserting it from the end of the nozzle upwards (see the picture below). Such a cleanup may even be done as a preventive maintenance, and it works very nicely.

The danger may be to enlarge the nozzle in the end (metal against metal), so I don't do it that often. At least I make sure my wire is clean and perfectly straight. But sometimes it works fine and drags the dirt that does not want to go through it the other way (ie. I do this when pushing hard downwards does not seem to restore a proper flow).

Ugly burnt wooden dirt brought up from the nozzle by the wire

Use a piece of ABS/Nylon to "fish" the remaning PLA

I first heard of this trick from fluxline : "to fish out the remaining PLA I mucked about inside the brass with a piece of ABS filament, the PLA stuck well without melting the ABS".

By letting the temperature go down a bit after heating seriously, it's easier to remove all the PLA at once compared to the hex screwdriver trick.

Now I have switched to a piece of trimming line (Nylon). It is much better for me because it melts at higher temperature and does not become too soft even at 230°, so you can go fishing longer in the nozzle from above without the risk of leaving some ABS in the middle of your PLA (which is more annoying to get rid of afterwards).
Successive use of Nylon to cleanup a nozzle throughly, by whosawhatsis's blog


  1. Thanks I need to try this as I couldn't take apart the nozzle before. The hard part is to find a thin enough wire.

    1. I think 30W gauge wire is ok, and you probably find very small quantities on ebay for a few bucks b/c they are used to hack game consoles
      You may double check the diameters here http://en.wikipedia.org/wiki/American_wire_gauge

      - Cheers