Abnormal number of filament feed failures on UP300

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cj7hawk
Posts: 96
Joined: Tue Dec 25, 2012 7:52 am

Abnormal number of filament feed failures on UP300

Post by cj7hawk » Sat Dec 22, 2018 3:00 pm

Just noticing I have quite a few feed failures, where the print just stops, often immediately before printing the raft.

I have had only 1 feed issue with my old UP Mini since I bought it, and that's about 25+ KG of plastic, but I'm getting them regularly with Tiertime filament on my UP300.

Interestingly, if the raft prints, the rest of the model usually prints, but not always.

Has anyone else had this problems?

David.

TiertimeBrook
Posts: 97
Joined: Tue Oct 16, 2018 8:25 am

Re: Abnormal number of filament feed failures on UP300

Post by TiertimeBrook » Wed Dec 26, 2018 1:37 am

Hello David,

Our engineers are working on this issues now because we received some same cases with yours,
After we got officially solutions, We will got you informed.


Regards
Brook

cj7hawk
Posts: 96
Joined: Tue Dec 25, 2012 7:52 am

Re: Abnormal number of filament feed failures on UP300

Post by cj7hawk » Mon Dec 31, 2018 12:21 pm

Thank you - Standing by to hear more.

cj7hawk
Posts: 96
Joined: Tue Dec 25, 2012 7:52 am

Re: Abnormal number of filament feed failures on UP300

Post by cj7hawk » Mon Jan 28, 2019 5:38 am

Hi Brook,

I have some updated information today - I had significant feed problems today, to the point that I could no longer get a print. It took me about 6 hours to solve.

First, I noted that when I reduced the extrudion width to address the infill problems in up studio, I had very rapid problems, and they continued to get worse and worse. I eventually pulled out a new roll of Tiertime filament, and while it fed OK when replacing the roll, it wasn't capable of even laying down a raft... By the time I got to print, nothing at all came out. Strange.

So I started adjusting settings, and found that the relationship appeared to be due to backpressure at the nozzle. If I had more density of plastic on the lift, it simply wasn't extruding and would just start ripping a hole in the filament.

So I eventually gave up on settings, pulled the extrusion head off, and had a look. There was solidified lumps of filament stuck in the gear teeth of the feed wheel. I took a pocket knife and dug out these plastic lumps that were fused to the feed mechanism and it seems to be working correctly now ( but still getting infill problems ).

Here's the difference I noted -

If the teeth are filled with solidified filament particles, it's not possible to push a clean piece of filament through the mechanism without feeling it bind. If the teeth are clean, you can easily push a new piece of filament through the mechanism, and actually feel the resistance of the teeth and servo as a regular change in pressure while pushing. The feel enough tells you.

This is after 1.5Kg of filament BTW, so that kind of buildup means two things.

1) The servo is getting WAY too hot. I think maybe you need to thermally bond a heatsink to the bottom of it. Sticky thermal transfer tape would probably be enough, and would help greatly. Getting airflow to the teethed cog might also help. If it's getting hot enough for plastic to stick to it, then it's probably something that will be a long term problem in the UP300 with so much heat in there.

2) You probably need to change the feed teeth cog to a different shape, that is more "self cleaning" and perhaps even monodirectional.

You also probably need a feed "stuck" sensor somewhere, to make sure that the plastic is actually feeding while printing. It might even be possible to save a print mid-print if it can be unstuck.

Hope this helps - I may try machining up some new toothed feed cogs to test this out next time it happens.

David.

End note: nope, after about 4 hours, it's air printing again, even with the freshly cleaned feed mechanism. Seems the problem might be something else.

cj7hawk
Posts: 96
Joined: Tue Dec 25, 2012 7:52 am

Re: Abnormal number of filament feed failures on UP300

Post by cj7hawk » Mon Jan 28, 2019 12:55 pm

I took the print head apart without removing the filament so I could see what was wrong, and having cleaned it, found a clear indication of the filament being chewed out, with pieces still stuck in the feed mechanism.
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IMG_20190128_182324.jpg (88.75 KiB) Viewed 520 times
So I started to wonder if something else could be at play and removed the old 0.4 nozzle in case it had become clogged with something that was causing it to clear when I removed the filament, but slowly worked back into place when I was extruding.

I'll see how the new nozzle goes tomorrow.

David

cj7hawk
Posts: 96
Joined: Tue Dec 25, 2012 7:52 am

Re: Abnormal number of filament feed failures on UP300

Post by cj7hawk » Tue Jan 29, 2019 6:34 am

Seems to be printing Ok today, no bad sounds, no feed problems. I flushed the head after removing the nozzle and filament feed bracket by pushing a piece of clean filament through it, and found some shiny bits, which could have been metal fragments from the previous head and/or heater, and might have been responsible for clogging the nozzle, which would explain a lot. They also might have come from somewhere else though as I wasn't specifically looking for things like that.

The current test has completed OK - well, a few minutes off, with no further problems, and I couldn't get past about 10% last time, so that's a good outcome and it might be that contamination in the print head was the only issue.

After a few more prints, if it's OK, then I think we can blame contamination in the print head as the likely cause. I'm trying to clean out the previous head in solvent now, so if there's anything visible in the solvent afterwards, then I'll take note.

David.

Furn
Posts: 17
Joined: Fri Sep 02, 2016 10:23 pm

Re: Abnormal number of filament feed failures on UP300

Post by Furn » Mon Feb 04, 2019 8:59 pm

David when i am changing filament i cut the one i am removing close to the print head and extrude the remainder though with the new just touching the old one . i don't withdraw filament anymore as sometimes as the hot filament comes back up past the feed small pieces get caught in the gear and cause a jam . have been doing this on both my up box and up300 and greatly reduced the number of failures.

Owen Sparks aka Marksman
Posts: 587
Joined: Tue Mar 15, 2016 9:56 am

Re: Abnormal number of filament feed failures on UP300

Post by Owen Sparks aka Marksman » Tue Feb 05, 2019 8:14 am

I concur on the "never withdraw" filament swap method.
Owen S.

cj7hawk
Posts: 96
Joined: Tue Dec 25, 2012 7:52 am

Re: Abnormal number of filament feed failures on UP300

Post by cj7hawk » Sun Feb 10, 2019 3:17 pm

My experience and investigations suggested that if the filament jams, it will clog the feed gear, but nothing I saw suggested that hot plastic was causing clogging. If I had to guess, it might have even had a cleaning effect on smaller particles.

Ripping seems to cause the most problem, but doesn't seem to affect traction as much as I would have imagined, as even a dirty gear still feeds plastic until it shreds.

In any case, I haven't had any new feed problems, so I think contaminants are getting into the system.

Still, the suggestion does have merit, thanks. I haven't had the kind of feed jam you're talking about but that doesn't mean I won't I the future.

Cleaning an old head is challenging. I need to get some small vials that I can fill with MEK to dissolve the plastic and clean them out... From what I saw during disassembly, I'm guessing there was some coating flaked off during assembly of the heads, but unless others get the same result, I can't tell whether it was just mine or a manufacturing problem.

David.

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