AA Core Jammed with Metal, Manufacturer Defect?

[whoneyc 10]

I recently had one of my AA cores jam.  This isn't a new thing, but it was much worse than usual.  I was running PLA.  I tried to move the filament jam at T=200C, but it remained stuck.  I had to cut the filament at the print core to get it out to look at it.  

 

 

As you can see, near the cut there is a blob of filament preventing movement.  This jam was not discovered until after a run, and the heat of the core with pressure and a lack of movement caused the softened filament to blob up there.  But that does not explain why I could not pull the filament back out.

 

To address this, I heated the core and popped it out of the printer while hot.  I carefully unscrewed the brass tip from the Olssen block with a wrench.  What I found surprised me.  At the tip of the filament cone was a sliver of the brass from the nozzle.  Even with everything unscrewed, the nozzle dangled from this metal sliver which was bound by the plastic.  Being grumpy and burned several times from playing with a hot core, I was not thinking clearly, and I failed to take a picture of the bit in question before trashing it.  (note to self, go dig through shop trash).

 

I took the barrel out of the core and used a torch to melt out the remaining plastic.  Once reassembled, I did a hot/cold pull on the core until it came out clean.  The core was then tested and was found to extrude properly.

 

 

 

 

 

 

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Edit: I found the piece and took photos.  The metal has since sheared off from the melt, but is still visible sticking out of the surface.  I apologize for the low quality microscope pictures.  I can't wait for my GF to upgrade her scope.

 

 

 

 

Due to an accident reassembling the core, it sadly would not print.  The spring on the barrel was still too hot when I reassembled the core, and it pushed through the plastic clamp.  This means that the core will not sit properly and fails bed-leveling tests.  It is likely repairable.

 

I suppose if I had to ask the community a question about this, it would be WTF?!?!  Has anyone seen this before?  Since the Ultimaker warranty does not cover the cores, should I find the offending plastic with embedded metal and escalate this issue?

 

Note: I hereby attest that I have only ever used unfilled PLA with that core.  There has never been foreign material introduced from brass-fill or similar filaments.

Edited November 25, 2018 by whoneyc
Adding Picture

[Smithy 1,144]

Is it possible that the brass you found was from the nozzel? I mean that due the unscrew of the nozzle some brass came off? 

 

UM uses a very high torque for the nozzle and it is not made to take the nozzle off. So the chance is normally very high that you damage your print core if doing so or that the core will leak after putting everything together due to less torque.

[whoneyc 10]

13 minutes ago, Smithy said:

Is it possible that the brass you found was from the nozzel? I mean that due the unscrew of the nozzle some brass came off? 

 

UM uses a very high torque for the nozzle and it is not made to take the nozzle off. So the chance is normally very high that you damage your print core if doing so or that the core will leak after putting everything together due to less torque.

 Possible but unlikely.  The metal was embedded in the melt before unscrewing.  Picture added in edited OP.

[SandervG 1,521]

I've never heard or seen it before. What you noticed in the filament, was it silver or brass? I know you said it was a brass sliver, but in the scope-photo I can't really see anything brass. 

Have you been using Ultimaker filament or also third-party filament? I'm asking because it is possible with cheaper filament that dirt or other particles can end up in the filament, and perhaps such an artifact was blocking your nozzle. I have seen such reports, but not with Ultimaker filament. 

 

@Smithy's suggestion is also a good one. I imagine that the location of this brim could tell us if it could be part of the block or not? (I imagine if it lies somewhere on top of the melted filament it can have happened during disassembly, but if it was in the filament or even in the nozzle it probably was in there longer already. 

[whoneyc 10]

On 11/26/2018 at 6:03 AM, SandervG said:

I've never heard or seen it before. What you noticed in the filament, was it silver or brass? I know you said it was a brass sliver, but in the scope-phot

o I can't really see anything brass. 

Have you been using Ultimaker filament or also third-party filament? I'm asking because it is possible with cheaper filament that dirt or other particles can end up in the filament, and perhaps such an artifact was blocking your nozzle. I have seen such reports, but not with Ultimaker filament. 

 

@Smithy's suggestion is also a good one. I imagine that the location of this brim could tell us if it could be part of the block or not? (I imagine if it lies somewhere on top of the melted filament it can have happened during disassembly, but if it was in the filament or even in the nozzle it probably was in there longer already. 

 

Just in case it is difficult to discern: I am talking about a brass sliver NOT as brass silver.  The sliver/silver can be confusing.

 

In the image, there is a slightly browner blurry spot.  This is the brass I am referring to.  The lighting in combination with the fact that it is partially embedded in black plastic makes it hard to get a good color read.  The color of the brass part in the picture looks similar to the fingertip on the right side of the image in color.  The silver strand next to the brass appears to point to it.  This is a ripple on the surface of the plastic, and is neither an inclusion nor debris.

 

The filament I was using is PLA from the 3D Universe house brand.  The page for the filament can be viewed here.  While it is not verified to be 100% perfect like Ultimaker filament, I have had no problems with it in the past and I have heard of no one else having problems.

 

To debunk my own claims: it is possible that debris contaminated the filament from my shop.  I do not have one of those sponge filament wipers (yet) added to the feeder inlet.  However, I don't work with much brass/bronze/copper, so a sliver like this would have to be errant contamination from an unknown source.

 

When I pulled the offending plastic clog from the disassembled core, the material appeared to be connected to either the screw ridge at the cut end of the nozzle or the surface of the cut end itself.  This was a very fine connection, and it snapped off within a second that I gave it a tug with force perpendicular to the normal flow through the nozzle.  Any metal not embedded in the plastic which was still attached is likely unrecoverable from the shop floor, disguised among the wood chips, pet hair, plastic pellets, and squished sycamore moth larvae.  

 

To determine the level of embedding of the metal shard in the filament, I can perform a destructive test on the sample to completely carbonize the polymer plug and extract the metal (aka, I go outside with a butane torch and nuke the thing).  

 

Please note another addendum to @Smithy's suggestion.  The core has been used and abused over the year, but it has never been disassembled prior to this clog.  If there was some internal damage to the nozzle, it would not have been due to repeated disassembly and reassembly by me.