Allan Bennett Posted January 26, 2023 Share Posted January 26, 2023 I've had my Ender 3 for a month now, and up until a couple of days ago it gave no problems. Then I noticed that the feeder that pushes the filament into the tube to the nozzle was sort of jumping during about the first 10 minutes of a print, as if it were struggling to feed the filament. At that time the prints were still coming out good. Today the feeder is stalling -- constantly 'bumping' but unable to feed the filament -- after about 15 minutes into a print, the first 3 layers or so having gone down successfully. On pulling the filament out I can see that there's a thickening a couple of inches above the nozzle, presumably due to the heated filament swelling to fill the silicone feed tube while under pressure from the feeder. I replaced the nozzle with the spare that was supplied with the kit, but the same thing happened. I was able to clean out the nozzle I'd removed quite easily by pulling on the stuck bit of filament, and then pushing through the cleaning wire. Any ideas why this blockage should be happening? I'm using Creality's black PLA with a nozzle temperature of 200C, and no settings have been changed since the 3-week run of successful prints. Quote Link to comment Share on other sites More sharing options...
Flying Squirrel Posted January 27, 2023 Share Posted January 27, 2023 Have a look at the 'arm' that you pull back to load the filament, check for cracks Quote Link to comment Share on other sites More sharing options...
Flying Squirrel Posted January 27, 2023 Share Posted January 27, 2023 Also clean the knurled wheels that grab the filament and make sure the tensioner is set correctly Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted January 27, 2023 Author Share Posted January 27, 2023 Thanks for the replies, I've checked the points you've mentioned but the problem doesn't seem to be at the feeder; from the way the filament has been distorted just above the nozzle it looks like there's been plenty of force pushing it, but it simply hasn't been able to get out of the nozzle. The nozzle temperature shows a steady 200C throughout. Would increasing the nozzle temperature help and, if so, how high can I go for PLA? Quote Link to comment Share on other sites More sharing options...
PeterF Posted January 27, 2023 Share Posted January 27, 2023 Have you checked the condition of the end of the PTFE tube in case that has distorted or the condition of the connector that the PTFE tube engages in. Is this the same reel of filament that you have been using up to now or a new reel. Different makes of PLA have subtly different temperature requirements for optimum extrusion. I have seen it claimed that different colours of filament within the same brand can show this. When trying something new you can always print a temperature tower test piece from Thingiverse to determine the optimum temperature. If the thermocouple in the hot end has developed a fault or has been dislodged it may result in a cooler nozzle. Do you have cleaning filament that you can run through the system. Try an extra 10 degree. Quote Link to comment Share on other sites More sharing options...
Flying Squirrel Posted January 27, 2023 Share Posted January 27, 2023 Hmmm, 200C should be plenty for PLA, in fact lowering the temp may help more than raising it. If the filament is softening a 'couple of inches' above the hotend this indicates an issue with the heat break not doing it's job Quote Link to comment Share on other sites More sharing options...
PeterF Posted January 27, 2023 Share Posted January 27, 2023 25 minutes ago, Flying Squirrel said: Hmmm, 200C should be plenty for PLA, in fact lowering the temp may help more than raising it. If the filament is softening a 'couple of inches' above the hotend this indicates an issue with the heat break not doing it's job If this is right could the hot end fan not be working as well, sometimes the fan can draw in whispy filaments. Quote Link to comment Share on other sites More sharing options...
Flying Squirrel Posted January 27, 2023 Share Posted January 27, 2023 Yes, that's a very good point Peter. Maybe also try a new nozzle although I would have thought if the first 15mins are fine it would be OK. Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted January 27, 2023 Author Share Posted January 27, 2023 Thanks for all those suggestions. It's the same reel of filament I've been using from the start. I did take out the PTFE tube when I was replacing the nozzle, and it looked okay except it had a slightly raised ridge around its outside where it enters into the nozzle heater housing. I scraped that off with a hobby knife in case that was stopping it seating all the way down to the nozzle, but there was no sign of PLA leakage there anyway -- I was using black, so it would have been noticeable. Yes, Flying Squirrel, it's the fact that the flow stops after about 15 minutes that's a bit baffling to me. I'll try reducing the temperature 5 degrees in case your theory about the heat break (what's that exactly) is correct. Quote Link to comment Share on other sites More sharing options...
PeterF Posted January 27, 2023 Share Posted January 27, 2023 Here is my spare hot end (not an Ender 3), the heat break is the finned section that the last 2 to 3 cm of the PTFE tube goes through and a fan blows cooling air over the fins. It stops heat conducting back up the tube so that the filament does not start to melt until the very hot section where the heating element is. 1 Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted January 27, 2023 Author Share Posted January 27, 2023 Thanks PeterF, I didn't dismantle mine enough to see all that. Makes sense. I'll check the action of my fan -- it certainly was working a couple of days ago. Quote Link to comment Share on other sites More sharing options...
Martian Posted January 27, 2023 Share Posted January 27, 2023 Just to be clear the heartbreak is the section of unthreaded between the heat block and the finned heatsink . Flow problems are nearly always to a burnt filament deposits in the heat breaks and ptfe tube ,a stripdown to replace heartbreak and ptfe tube ,be sure to use heatsink compound on the threaded part of heatbreak going into the heat block only. It's part of owning a 3d printer to be able to recognise the problems and be able to effect a fix. Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted January 27, 2023 Author Share Posted January 27, 2023 11 hours ago, Flying Squirrel said: Hmmm, 200C should be plenty for PLA, in fact lowering the temp may help more than raising it. If the filament is softening a 'couple of inches' above the hotend this indicates an issue with the heat break not doing it's job I think you've hit the nail on the head! The hot end fan isn't running at all. I don't know when it stopped, but I'm wondering if it's only the low temperature of my unheated workshop (aka garage) keeping the heat block cool that allowed me to print earlier in the week. Mid this afternoon, after a couple of failed attempts to print, the ambient temperature dropped and I was able to complete a 90-minute print with only a few judders of the feeder. I've checked the fan connection to the motherboard, and it appears to be good. The motherboard fan came on after a while, so at least there's a 24v supply there, so tomorrow I'll check the voltage where it goes into the fan, to make sure it's not disconnected somewhere along the way. I saw in another forum that the fan can be disable by the splicer, but I've checked and the setting on mine (Creality Slicer 4.8) is for fan to be on after the 4th layer. Hmmm, I wonder if the connectors to the motherboard are wrong way round, and the motherboard fan came on after 0.8mm or the 4th layer. The two fans are connected the way they were when I received the Ender, so that's another thing to check tomorrow. The 2-pin black/yellow plug at the left is the hotend fan; the 2-pin black/red one is the motherboard fan. Can anyone check if their connections are the same on their Ender 3 board? Quote Link to comment Share on other sites More sharing options...
RottenRow Posted January 27, 2023 Share Posted January 27, 2023 Hi Allan, I found this on the internet, it shows that your fan connections are in the right locations. Do you know if the hot end fan and the board fan are controlled together, or have separate control? Brian. Quote Link to comment Share on other sites More sharing options...
PeterF Posted January 27, 2023 Share Posted January 27, 2023 I thought the hot end fan was always on once the hot end gets above a certain temperature and the part cooling fan was often off for the first few layers and then turned on. Quote Link to comment Share on other sites More sharing options...
David P Williams Posted January 28, 2023 Share Posted January 28, 2023 I had a similar problem on my Anet printer. The fan would sometimes go if I flicked the vanes,but not always. Bought a new fan (cheap) and it’s been fine since Quote Link to comment Share on other sites More sharing options...
RottenRow Posted January 28, 2023 Share Posted January 28, 2023 According to the diagram that I found on the internet (shown 3 posts above), there are three fans. The hot end fan connector is one of the green screw terminals along the edge of the board (hidden under the wiring on Allan's photo), I would check that the connections there are okay. Check that one of the wires hasn't either fallen out of the terminal, or been tightened onto its insulation. It will be the thinner wires, closest to the power input connector. The two small white connectors with the blue/yellow and red/black wires that Allan is referring to are the part cooling and board (case mounted) fans respectively. Brian. Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted January 28, 2023 Author Share Posted January 28, 2023 Thanks for confirming my fan cable connection RottenRow. When I Googled for such a diagram I didn't get that one, and the ones I did get were usually a slightly different board with only a single socket where there's a pair of sockets on mine. Anyway, that rules out one thing. Next thing I've got to check into is several references to two fans at the print head -- one to keep the filament feed cool, the other to cool the print. In my case the fan that's mounted on the front of the print head which I assume is the 'hot end fan' because if's facing the metal feed tube and is described as such in how-to videos, has black/yellow wires so is preumably the one that's plugged into the board as shown in RottenRow's diagram but is described there as the 'part cooling fan'. I need to double-check those wire colours, for in videos I've seen about replacing that fan, it has black/red wires. I haven't yet taken off the other device on the right side of the print head. It looks like it should be a fan, though it's visually bery different from the front one, and has black/red wires, which would seem to match those shown in the diagram as 'H Red/black hot end fan'. Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted January 28, 2023 Author Share Posted January 28, 2023 Problem solved Looking more closely at the print head I realised that the fan with the black/yellow wires is the one at the right, which directs air onto the print. The black/red wires from the front fan go to the two screw terminals at the back of the board marked 'H' on the plan posted by RottenRow. Having realised that I then checked with my voltmeter to verify that there was 24v at those terminals (there was) and I noticed that the black wire was in the socket with the screw tightened down, but was loose. It was below the clamping plate, so wasn't being clamped when the screw was tightened. Replacing it correctly has the fan working again. Thanks to everyone for their advice and patience! 4 Quote Link to comment Share on other sites More sharing options...
RottenRow Posted January 28, 2023 Share Posted January 28, 2023 Well done Allan, It's nice to have a simple solution to something for a change isn't it! Brian. Quote Link to comment Share on other sites More sharing options...
Allan Bennett Posted January 28, 2023 Author Share Posted January 28, 2023 Being new to 3D printers it took a prompt like yours about temperature too high to start me heading in the right direction. While sorting this issue I've learned a lot about how the machine works. All thanks to this great forum and its contributors. Quote Link to comment Share on other sites More sharing options...
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