Nozzle blockage internally

[AledEvans 0]

Hi there,

 

So my print core seems to be completely blocked after a period of dormancy and i think the PVA has fully carbonised inside. I have tried hot and cold pulls but the material seems to me only just melting in the nozzle and nothing coming out the other side. I have tried to unblock with a needle (a thinner one may actually be the solution)

 

Dismantling it looks like a chore but just wondering how close i may be to the last chance saloon or if there was a way to more easily remedy the problem? 

 

If anyone has had a similar experience it would be great to know how you solved it - and if it is time to maybe just buy a new print core?

 

Thanks!

 

[Shadowman 53]

I wish I could help you get the Print Core cleaned. I do recall reading about manually increasing the Print Core temp to a temperature higher than is done when you use the hot and cold pull menu and then inserting the filament, letting it cool, and then doing a hot and or cold pull. Do a Google search.

 

Here is a fellow that does it a bit differently.

 

 

Now.....

 

When you say domancy do you mean when only using the AA Print Core and yet PVA remains in the BB Print Core?

 

I ask because we realized after a minor issue that even when the BB Print Core is not part of the print it still heats up and we found that the PVA would begin to burn within the Print Core. 

 

We did not experience a total blockage however, we had to remove a significant amount of brown carbonized material.

 

Since then we unload the PVA after every print and reload as needed; even if the next print uses PVA as the risk is simply to high if we forget run a simple quick print.

 

Add to this we keep spare Print Cores on hand.

Edited October 23, 2018 by Shadowman
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[AledEvans 0]

8 hours ago, Shadowman said:

When you say dormancy do you mean when only using the AA Print Core and yet PVA remains in the BB Print Core?

 

I ask because we realized after a minor issue that even when the BB Print Core is not part of the print it still heats up and we found that the PVA would begin to burn within the Print Core. 

 

We did not experience a total blockage however, we had to remove a significant amount of brown carbonized material.

 

Since then we unload the PVA after every print and reload as needed; even if the next print uses PVA as the risk is simply to high if we forget run a simple quick print.

 

Add to this we keep spare Print Cores on hand.

 

Shadowman, 

 

Thanks very much for your response. The problem is exactly as you have understood. We have been frequently using the PLA material and have not used the PVA material or extruder.

 

when you say 'we had to remove a significant amount of brown carbonized material' did you do this using the hot / cold pull methods? 

 

I have read elsewhere that an acupuncture needle can be used to poke through the end of the nozzle when the filament is heated to so I feel a combination of these methods should be used. 

 

I think a spare print core is also probably a good idea.

 

Thanks again 

[SandervG 1,521]

Hi @AledEvans,

 

thank you for your post. Sorry to hear it sounds like you're having some issues with your print core.

It's always recommended to remove the PVA after printing when you're not using it. PVA is very sensitive to moist and will even attract moist from the air and it will get soft and degrade. (You can bring it back to life by heating it up in a box on your build plate but it's better to avoid this). 

 

You can indeed use an acupuncture needle and see if you can perforate the clog from the outside in, and do some more hot/cold pulls afterwards. Unless I'm wrong I think we have never had a print core we couldn't unclog, so there should still be hope ? (If time is of the essence, I can recommend indeed having an additional print core on stock, so you can replace the print cores and clean the clogged one while not loosing any print time.) Hope this helps!

[Dim3nsioneer 557]

In addition I would recommend to put an AA core in slot 2 if you don't use the second material for some time but perform single extrusion prints. The reason is that the active leveling heats both cores up and that means an unnecessary heat up of the BB core with the rest of PVA inside.

[Shadowman 53]

4 hours ago, Dim3nsioneer said:

In addition I would recommend to put an AA core in slot 2 if you don't use the second material for some time but perform single extrusion prints. The reason is that the active leveling heats both cores up and that means an unnecessary heat up of the BB core with the rest of PVA inside.

 

Thank you for the suggestion as it will be followed.

 

Any idea why the second Print Core has to be heated; am I missing something?

 

It seems as though Cura could turn a Print Core on and off as the print demands or even manually within the settings menu.

 

 

 

[Shadowman 53]

5 hours ago, AledEvans said:

 

Shadowman, 

 

Thanks very much for your response. The problem is exactly as you have understood. We have been frequently using the PLA material and have not used the PVA material or extruder.

 

when you say 'we had to remove a significant amount of brown carbonized material' did you do this using the hot / cold pull methods? 

 

I have read elsewhere that an acupuncture needle can be used to poke through the end of the nozzle when the filament is heated to so I feel a combination of these methods should be used. 

 

I think a spare print core is also probably a good idea.

 

Thanks again 

 

You are welcome.

 

Initially I followed the menu; meaning hot then cold however, I was not successful until I did “many” hot pulls in a row and the a couple cold pulls.

 

I am confident that you will get it cleared.

 

In my opinion this information should be boldly presented when you receive the printer.

 

Takes care.

[Dim3nsioneer 557]

1 hour ago, Shadowman said:

Any idea why the second Print Core has to be heated; am I missing something?

 

You mean for the active leveling? Well, the S5 does perform a z offset calibration right at the beginning of the active leveling so there might be material hanging from the second nozzle and therefore it has to be heated.

 

[Shadowman 53]

Gotcha...

 

I check the tips prior to beginning a print but recognize that some folks many not.

 

It still seems to be unnecessary to maintain heat with the second Print Core when not called for in the print.

 

Even the initial Print Core offset checking between the 2 Print Cores when the Active bed leveling begins seems to be unnecessary if only one Print Core is being used.

 

Thank you for your insight.

 

 

[Dim3nsioneer 557]

43 minutes ago, Shadowman said:

It still seems to be unnecessary to maintain heat with the second Print Core when not called for in the print.

 

After active leveling the second print core should not be heated anymore when not used anymore in the same print. Did you observer something else?

 

44 minutes ago, Shadowman said:

Even the initial Print Core offset checking between the 2 Print Cores when the Active bed leveling begins seems to be unnecessary if only one Print Core is being used.

 

Fully agree. Let's see what future firmware upgrades will bring...

[Shadowman 53]

8 minutes ago, Dim3nsioneer said:

 

After active leveling the second print core should not be heated anymore when not used anymore in the same print. Did you observer something else?

 

 

Fully agree. Let's see what future firmware upgrades will bring...

With regards to the second Print Core remaining active post active bed leveling; ugh... I assumed so because during the active bed leveling they both glow red and then afterwards both remain blue and or flashing blue. As such I assumed it remained at a minimum temp effectively ready to extrude.

Edited October 24, 2018 by Shadowman
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[jbob 0]

I have taken to doing a material change between prints.  I don't actually change the material, but when it reloads the PVA, I let it extrude until i get about six inches without bubbles or debris.

 

it is possible to change the nozzle without forking over 100$ for a new print core.  I heat up the print core, remove it from the machine and remove the nozzle quickly.  One needs to be ready to work before heating up the core.  Make sure you use two wrenches.  One wrench goes on the nozzle and the other one on the big square heat block.  Make sure you don't allow any torque where the other fitting threads into the top of the hot block.  It is very easy to snap off this thin walled connection.  It is super thin to keep the heat in the bottom.

 

I've succeeded in clearing a clogged hot end by chucking up the nozzle in my lathe and putting a .6mm drill bit in a drill chuck on the tail stock.  I spun it by hand as I felt that would reduce the risk of snapping off the drill bit and allow me to immediately stop if it looked like I was drilling out the brass.  Then I flipped the nozzle around and chucked up a drill bit slightly smaller than the end the filament enters.  I spun it around with mild pressure on the drill bit until I felt the plastic break free of the nozzle and start spinning.  I only did this because I didn't have any spare nozzles.  I have a 50% success rate on this because the second time I tried it, I drilled the orifice off the nozzle body...  turned a .6mm nozzle into a 6mm nozzle!  See below where I describe removing the nozzle from the hot end.  There are videos online. Some of the videos try to trick you into buying special jigs/tools, neither of which I own.

 

I've also tried ultrasonic cleaning and dissolving with either hot water, acetone or alcohol.  These attempts all failed.

 

When you buy nozzles, make sure they are for the S3 (if that is what you have.)  The S2 nozzles are wrong.  the correct nozzles are cheap on the south american river web site.

 

I have taken to coating the insides of my nozzles with Molykote G-N assembly paste.  It contains molybdenum disulfide which plates out on the brass...  Haven't been doing the G-N thing long enough to say if I think it works.