3D Printing : Unclogging The Hot End

In my last post on 3D printing, I mentioned that the hot end of my 3D printer was clogged up with some red PLA. I got some ideas from asking around on handling this, and I ended up trying the “drill it out” solution first. Well, the first thing I did was place an order for a new hot end, that way I knew I had a replacement on the way in case I destroyed my current hot end. This kind of seemed to work, the drill went through… but I was a little offset and ended up widening the hole in the PEEK insulator that the plastic is meant to travel through. I don’t know how much this matters, but it was probably not good.

After drilling through, I was able to use a thin metal tool to pull a lot of red plastic out. After this, I grabbed a strand of black ABS, and started pushing it it through the hot end, while the hot end was heated up. This seemed to work, I was getting red plastic coming out the bottom of the hot end for a while. I kept at this, trying to keep pushing things out until I was getting black plastic, and this seemed to work. Next, I switched to a white ABS to push through until another color change, I wanted to make sure I had a clear hot end. While pushing out the remaining black plastic, I was getting spurts of red plastic extruding as well.

After pushing this for a while… the entire thing started clogging up. At this point, I spent a few hours using different tools to push in plastic and pull it back out, trying to clear whatever the jam was. Every time I would think I had made a lot of progress on clearing the clog, having pulled out a ton of plastic, I would try pushing a strand of plastic through and it would always end up stuck again.

While trying to unclog my hot end, I noticed all of a sudden that my hot end was down to room temperature, and the software on my laptop was giving me an error that there was no connection to the hot end. After making sure it was safe to do so, I disconnected my hot end to check it out. One of the cables had become frayed. At this point, I got out my soldering iron, and soldered the wire back together. Luckily this fixed the connection, and I was able to heat up my hot end again.

I was still not able to clog it, and I decided to try out some new problem solving ideas. I figured at this point any clog would hopefully be ABS and not PLA, I had managed to extrude a lot of ABS since digging out the PLA. ABS plastic melts in acetone, PLA does not. When my hot end was fully cooled off, I used my clamp to hold it vertically over a container of acetone, and poured some acetone into the top of the hot end. Again, if I ruined things I did have a new hot end on its way in the mail, so I was willing to learn through making mistakes on this current hot end. After leaving this for a while, I did notice a strand of partially dissolved plastic in the acetone, which meant that something had come out of the hot end.

I left the hot end outside the acetone for a day to make sure it was fully dried and cleared off, and plugged it in again to heat it up and see if I could extrude some plastic. Again, I was having the same problems, where I was getting no plastic leaving the tip of the hot end. I am wondering if, at this point the hot end is jammed with plastic from the PEEK insulator that I scraped off with the drill when I originally tried to remove the PLA plastic? I might spend some more time trying to clean out the hot end this weekend, maybe bring it to Metrix to see if anyone there has ideas. Worst case this thing is broken, and I use the new hot end on its way in the mail.


Joseph Stankowicz is a software engineer who has worked in the video games industry for over eight years. The last two years have had a heavy focus on Unity development, where he helped ship over eleven titles to iOS and Android platforms. He also is really excited about 3D printing, and keeps his Solidoodle 3 printing out stuff as often as possible. You can view his LinkedIn profile here http://www.linkedin.com/pub/joseph-stankowicz/60/294/420

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Posted in 3D Printing
One comment on “3D Printing : Unclogging The Hot End
  1. Dragonhill says:

    Ill try to make a quick vid showing my solidoodle in action with PLA.. and slicer setting too.

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