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Da Clumsy Noob discovers a way to hot pull PVA midprint

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PVA....Cannot live without it, cannot shoot the nozzle when it clogs....



  1. Patience aplenty
  2. Airbrush needle or something like that with a nice teeny tiny point.


Issues to overcome:

  1. When printing and humidity strikes midprint, especially on long ones like I do on a constant basis
  2. Humidity will clog the nozzle as PVA pops and crackles, creating a carbonized mess inside as well as outside the nozzle
  3. If you pause the print to try this, it will not work because the nozzles cool down and you cannot adjust the temp more than +- 25¯C. By this time, the material is too cool to do anything with. *Are you hearing this firmware devs?


OK, now this is an issue that has plagued me ever since I started printing. AND continues to plague the industry as a whole. It is an unavoidable evil that must be dealt with. It does not matter whose PVA you are using.....it will happen.


The main warning sign is when the material is not printing like a solid wall, but starts to get very lacy. At this point, it cannot hold the material it is supporting and you may not discover this until the print is done and you just have a lot of time, material and expense down the drain.


SO! what to do, what to do.....


For some reason it occurred to me tonight that the solution (klugey as it may be) is to fake out a material change. Even if you have a brand new spool of PVA in there, if there is a clog, it will still not give full PVA service to the supports.


So, here are the steps ?


1. Go to the 'tune' menu and initiate a material change. This will heat the nozzle to the proper temp and hold it. It will also pause all printing ops and step you through all steps of replacing materials.

2. Once your material unloads, leave it at that stage. This will keep the temp up while not letting anything continue until you go to the next step.

3. Poke the heck out of it with the airbrush needle or something similar. Just be careful not to poke out the delicate nozzle tip.....

4. Take older leftover PVA, like those bits when it was changed out and leaves the parts that were in the bowden tube, and push it though.

5. Rinse and repeat until you get a clean thread of PVA going through.

6. Reload your PVA and start back up.

7. As it reloads, you will see a nice thread of material squishing out.


This is not as good as a hot and cold pull, but it can save a long print. It should also be mentioned that this is also available for the S5 as well.


The best solution would be something to allow a pause and temp control to the extremes that hot and cold pulls require to really get it out. *Ahem* firemware devs ?


Some may say that keeping the nozzle clean is the answer.....it is until you have a really long print, the humidity rises and starts to degrade the printing of PVA during that time. It can happen. It has happened to me as I do these massively long prints. Start with a clean nozzle and 5 days later, humidity strikes, and the lace pattern appears as the PVA starts to underextrude.


So, happy PVA supports all around fer everyone!!



Edited by kmanstudios
Added information in steps 1, 2 and the end of the procedure statement.
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Great workaround!  I will check around to see what needle spec it would take to safely enter that nozzle.


The comment on the rod bending prompted me to start a separate thread on a print core cleaning stand. I'm wondering if your technique could be incorporated into the design considerations for that device.


Gotta love the sharing here!


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I have used gauge 28 acupuncture needles but gauge 28 hypodermic needles are so much better because it is tubular with sharp edges that can scrape the gunk off the inside of the tip of the nozzle.  For several years I would ship a free one for all new people to my store but my supply has run dry (regulations made it difficult).  But a acupuncture needle works pretty well.


It just occurred to me that maybe I should cut the pointy tip off acupuncture needles!  To make them more flat.  Hmm.

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