Printing metal filaments

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maugseros
Posts: 15
Joined: Thu Aug 25, 2016 7:56 pm

Printing metal filaments

Postby maugseros » Tue Apr 11, 2017 2:56 pm

Just wanted to share my experience.

I switched out the nozzle on the left extruder with a SS .6mm nozzle in order to print some wood and metal filament. I flipped the bed over and put green painters tape on the glass and once I dialed in the correct nozzle and bed temperature, I got good adheasion and some really good prints.

Now the problem came when I went to switch back to PLA. I switched the nozzle back to the .4mm brass nozzle and everything seemed fine, but then I started getting these "blobs" on the exterior of my print. The blobs were easy enough to remove, and left little to no mar on the exterior surface of the print, but I didn't understand what was causing them. So i had to sit and just watch the print for a while until I spotted the culprit. The exterior wall of the print seemed to print fine, however when it was printing the infill, every once in a while a line of the filament would not stick to the previous layer. To which you would have this fine hair of filament sticking up to which the hot nozzle would eventually touch it and it would melt onto the nozzle. Once this happened a few times, a blob of hot filament would be on the exterior of the nozzle and would eventually drip off. Sometimes this blob of filament would just get buried on the inside of the print, other times it would get pushed to the outer wall of the print (which is these visible blobs I was describing).

In trying to troubleshoot what was going on, I noticed that there was a fine powder substance inside of the feeder tube. What it appears to have happened is that the metal filament left behind a powder residue. I speculated that some of this fine powder is getting picked up by the PLA filament and then getting mixed in with it, effecting the ability of the filament to "stick" to a previous layer, specifically on fine lines like the infill layers. So I took the feeder tube out and used compressed air to blow it out, took of the clear acrylic feeder cover and blew all that out with compressed air. I took the hot end off and blew down thru the white feeder tube with more compressed air, then took the nozzle off and blew through the hot end with more compressed air. I put everything back together and tried it again. The blobs were noticeably reduced, but still present.

This leads me to believe that there is still some reside in the hot end causing this. It's possible that purging enough filiment throught he hot end might eventually clean it out. I'm not sure, because I have a spare hot end that I have that I then put on the machine and then everything printed perfectly. I am now going to designate my original hot end for printing exotic filaments and the new one that I put in as PLA/ABS only.

Has anyone else had this experience?

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walshlg
Posts: 1228
Joined: Wed Mar 23, 2016 12:01 pm

Re: Printing metal filaments

Postby walshlg » Tue Apr 11, 2017 4:35 pm

I always worry about molten filament making a thin lining of the isolation tube, not enough to clog but enough to interfere and lead to those slow jams. I have experienced that.

If you are tearing down your hotend, may I suggest heating it up, removing the nozzle and running the 1mm wide wire from top to bottom only repeatedly, hopefully all the residual plastic will stick to the cold wire.

maugseros
Posts: 15
Joined: Thu Aug 25, 2016 7:56 pm

Re: Printing metal filaments

Postby maugseros » Tue Apr 11, 2017 7:43 pm

Well, I wasn't getting any "clogs", I believe it was a fine powder residue from the metal filament that the PLA is picking some of that residue up and then it's slightly altering the characteristic of it. When going slow and laying down a significant amount of PLA (like on the exterior walls of the part) it printed just fine, but on the very thin infill layers where the print head is moving fast, occasionally the PLA wasn't sticking to to previous layer. I even tried a different roll of PLA just to make sure it wasn't something specific to that roll (like it had absorbed too much moisture or something. BTW.. I keep all my PLA in a sealed container with a ton of silica beads). But I still got the same issue with a different roll of PLA.

I did heat up the hot end with a butane torch and ran the metal rod through it several times on top of all the compressed air I was using to blow it out. The fact that after I did all this the print was much better (but still getting SOME blobs) makes me think i was on the right track suspecting that this powder residue left over from the metal filament is the culprit. I think that if I just let the printer print out some more with that hot end that it would eventually clean it all out and it would have started printing fine.. but since I had a spare hot end already, I just decided to put that one in and keep my original one dedicated to printing exotic filaments.

So just a note to others who if you want to try out exotic filaments like metal/wood, or I would wager any filament that has something that is MIXED into it, you may want to think about buying an entire hot end and dedicate it to printing those exotics.


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