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Why so much crap in the nozzle?

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Hello guys.

Love the ultimaker, it has been our workhorse for past few months. We do a lot of in-house automotive engineering and this thing is printing prototypes about 50 to 80 hours per week for the past 4 months. We're printing exclusively with PLA, although we did try ABS once.

The nozzle seems to be generating a lot of buildup and I'm not sure where it's coming from. Starting last month, the print quality was getting progressively worse. I found myself doing the 'atomic' cleaning method almost every time we needed to print. Not good. We ended up getting couple of replacement nozzles from fbrc8 (thanks for super fast shipping!) and now the printer is well.

But I took the old nozzle and scraped the inside of it with a needle and found an incredible amount of junk in it. Below are pictures of what I found.


Clogged Nozzle


Clogged Nozzle Closeup


Clogged Nozzle Closeup 2


Some of the chunks are huge! No wonder I had to keep unclogging the nozzle almost every time we printed. Some of the degree looks carbonized/charred, some looks gray and flaky. The entire nozzle was completely caked with this stuff.

The only thing I can correlate to this massive buildup is using https://shop.ultimaker.com/product/22/PLASilver-Metalliccolor PLA, which we got directly from ultimaker website. The composition of the plastic appears to have specs of glitter like particles. The buildup most closely resembles that material. Anyone had problem with that?

I would like to prevent this from happening to the new nozzle in the future. Any tips and tricks?


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Silver metallic - I had something similar with a Faberdashery filament that had sparkles in it, which were bits of something different, and had bits deposited in the nozzle. If you are prototyping then just going for a plain colour PLA should be possible.

If you print at too high a temperature then the PLA will "boil" and leave deposits. I am guessing that 240c is your limit although I never go anywhere near that so I am not 100% sure.

If you are doing consecutive prints and leave the extruder temp. at the print temperature ready for the 2nd run, do not leave it without extruding for too long. Again not sure on this but more than 10mins might be too long -and I think this may well vary by filament as I have seen different consistencies being extruded by different filaments say after a 5 minute wait.

Mind you I have seen anything like your mess :)

We are in the middle of producing a wing mirror plinth for Lotus Elise S1s and are coating it in XTC-3D hoping that will give it a paint ready surface. Ever used that before?


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If dust and stuff gets on the filament while still spooled it can slowly make it's way through the bowden to the nozzle. That's one possibility.

Leaving the nozzle too hot but *not* printing can slowly caramelize the plastic. That's another possibility.

You should know that you can get an "Olsson block" replacement heater nozzle which then allows you to swap e3d nozzles very very easily. The e3d nozzles are only $10 each and you might consider them expendable. The other advantage of the Olsson block is you can use larger nozzles for much faster but lower resolution prints or a smaller nozzle for very small fine parts.

post #329:




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I use Ultimaker silver gray metallic PLA continuously for many months for the best of my prints. This particular variety PLA is generally suitable for easy and good to very good print results.

- PLA residues may cause problems in general when moving to ABS.

- Long idle times during active Hotend cause very quickly stubborn residues.

- Very slow printing in a temperature well above 210 degrees should be avoided.

- Temperature and speed must match the material currently in use.

- A misadjusted material feeder can cause many problems, you might try using alternate feeders.

- The ColdEnd could be worn.

- The Bowden should be checked for proper fit in the couplings and guides.

- When threading the new PLA you should make sure that the fractures are rounded as possible. A heated and therefore partially softer ColdEnd may be damaged, especially in the hot transition zone to the Hotend.


- Tetrahydrofuran is known as a solvent for PLA, but it is extremely harmful to health.

- A cautious Cleaning the exterior of the Hotend is possible with Dremel tools (brass brushes).

- Other Dremel tools (drill and various other attachments (...max 3.17mm) may be used cautiously manually.

- Abrasive paper with at least 500 grains per mm is suitable for cleaning the inside of the Hotend.

- Polishes and Polishing Tools for brass are suitable for a good visual restoration.



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