I was able to feed a guitar wire up from the bottom all the way up the PEEK and out, and it brought only some gooey filament up, which I cleaned off. Still, there could easily be more partial clogging in there. Would that explain the filament just refusing to advance five seconds after me pushing down on it caused it to advance?
]]>IanJohnson wrote:Try putting a screw through the bottom left hole of the fan into the left mounting stud. Maybe also run autotune while the fan is on so the hot end can compensate for any airflow that might be hitting the heater.
what is this autotune you speak of? I have not seen it on my stock SD3.. am i missing something?
It's on the calibrations page of the wiki.
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Fourth layer of printing and haven't had a drop-out yet.
johnforeman: look at my post two up from yours for my best guess about the autotune, there's a link there. Ian can confirm if that's what he meant, though.
]]>Try putting a screw through the bottom left hole of the fan into the left mounting stud. Maybe also run autotune while the fan is on so the hot end can compensate for any airflow that might be hitting the heater.
what is this autotune you speak of? I have not seen it on my stock SD3.. am i missing something?
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Also holds it up higher so it won't blow much on the hot end. Downside is it's a bit in the way of the filament's feed, so I can't see it, and kinks will be harder to clear out. And of course it looks entirely bogus and hacked together, sitting at this funky angle.
But I think it might work. Going to run wires now and give it a try.
(Incidentally, I think Ian's talking about the autotuning procedure described here.)
]]>If your filament is jamming and it doesn't seem to be clogged nozzles, then it could be getting too much heat into the black PEEK barrel. If the filament is too soft, too high up it can make it harder to extrude. Try putting a fan on it by replacing the screw that goes into the lower left corner of the motor with a longer M3 screw, running it through the upper left corner of a 40mm fan.
I have been having intermittent failure to extrude. It'll be laying down filament and then it'll just start laying down nothing but crumbs, while meanwhile the filament's not moving and the teeth are grinding away making dust. I've resorted to marking filament with a sharpie to see if the mark is moving. If, at this point, I take the filament in my fingers and push down on it, it'll often start moving again (as long as I don't push too hard and cause it to kink), and then run for a while before it stops again. I have been able to get a few print jobs to completion this way, but only by pretty much doing nothing but standing there watching them, so I can shepherd the filament through.
Note that there's no known change since when this was working fine. I've rechecked leveling and other calibrations. This happens with any filament, including filament that's been working fine, and I doubt I've suddenly had a change in a half-dozen separate spools of filament simultaneously. It started happening gradually and got worse over a week or two.
I've also tried cleaning a possible partial clog with guitar wire (nothing obvious came out), and with letting the filament cool to 160-170 and then pulling it up and out a few times (didn't get any evident debris or buildup out with it). I haven't gone as far as acetone or blowtorch. After all, I don't know of it's a partial clog in the first place.
Ian and 2n2r5 suggested in IRC this might be that the heat is travelling up the PEEK and getting the filament a bit too soupy up there, and that the fan mod above might help. I was never very clear on how I could mount it on a Lawsy MK4, and I exceeded my quota of stupid questions answered before I could get a clear idea of what mounting hardware I might need, so I ordered the fans anyway, hoping when they got here I'd be able to figure it out, and it wouldn't end up depending on me having some part I don't have (like it always does). After all, some of the mount points for the extruder are already the right distance for a 40mm fan, as shown in Ian's picture above.
Here's my extruder with the MK4 with its lower brace removed, and the 40mm x 10mm fan looking forlorn on my behalf:
If there weren't that big bump sticking out in the lower left, I think I could just swap the long M3 screws that go into the two bottom-most points with the shorter ones just above, using the extra length to mount the fan much as Ian has in his picture. Seems like this places the fan a little too low; the bottom half is blowing on the top half of the extruder itself. But since it can't be made to fit there anyway because of that protrusion in lower left, it's a moot point.
Ian suggested that the solution is to have previously found, or designed, some kind of custom mount that would hold the fan onto the MK4 in the right place, and to have printed it earlier. I suppose I could try to print it out now and hope I got really, really lucky, but I doubt that's possible. Then to get the mounting hardware that would need as well.
Heck, maybe I should just hacksaw off that protrusion. Though I assume that'd put the fan way too close to the PEEK and hot-end.
I also have an MK5 printed and stashed as my emergency backup. If I could make this all fit with an MK5 without any prints I don't already have, switching over to that could be an option.
And after all this, I'm still far from sure this is even going to help. Some of the symptoms Ian asked about (like that the problem wouldn't be there at the start of a job, but would creep in later) aren't happening for me.
Any advice for a poor little just-barely-past-newbie in over his head (again)?
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