Filaments jamming under 1.19RC4…



  • I'm having problems with all three filaments jamming in my delta diamond mixer where it was working okay before the RCs. I'm not certain where the problem is coming from. Auto calibration/bed probing and adhesion looks good. It's the same extrusion rates I've been using for a while now. Extruder motors fire up and not far into the print they're thumping away. I have tried turning down the extrusion rates down in DWC, but I'm not sure that is working because it doesn't seem to be affecting it.

    John


  • administrators

    Are you using firmware retraction, which is what deckingman recommends? If so, can you run a simple test to make sure that firmware retraction looks as though it is working properly in your setup i.e. all 3 filaments are retracted by the amount specified in M207 regardless of the mix?



  • Yes, I'm using hardware retraction. All three filaments are retracting in unison regardless of the mix (tool) I have selected though I can't say yet by how much. I am using M207 S3.50 F3000. I am running another test and I turned the extrusion rate all the way down to 50% using DWC. It's printing without jamming. I am gradually increasing to see where the breaking point is. I am at 65% now without issue.



  • I checked the filament extrusion distances and they are correct. I am currently extruding at 75% on all three extruders in order to keep the three filament equal mix tool (P3) from jamming. If I change the percentage mix on P3 using M567 while printing, the majority filament jams. So currently, all I can do is print with an equal mix of all three filaments because printing using any one of the filaments as a majority jams the hot end.



  • I'd say that's almost definitely a partial blockage in the hot end or too low a temperature or too fast an extrusion rate (print speed). Most likely the former of those three. The reason why it works better with an equal mix is probably that all 3 extruders are contributing equally towards pushing the filament through the restriction. So when you change the mixing ratio, the "majority filament" extruder can't cope without all the help it was getting from the other two.

    What filament are you using and what temperature are you printing at and what speed?



  • I'm using Hatchbox PLA at 200C at 30mm/s. Well it looks like I'm down now. I grabbed my trustly 0.4mm bit and decided to see if I could clear any potential blockage from the nozzle. I was at temp and it didn't go in very easily, while carefully turning and removing it, it broke off in the diamond hot end. Unless somebody knows something I don't, I believe I'm pretty much screwed 😞 I'm at a loss on how to get it out. A regular nozzle would be no issue. I tried extruding and the nozzle is firmly blocked with the broken bit 😞



  • Bit of a long shot but try heating the hot end to around 200, let it cool to around 150 then rapidly pull out the filaments. You may draw the broken bit out along with the plastic.



  • Thanks for the idea, but it was a no go.



  • I wonder if a strong magnet would let you draw the broken drill out of there.



  • Pull the nozzle and torch it. The filament will evaporate.



  • Bot, that's exactly where I went next! I have a very strong magnet and the bit is steel so I tried to pull it out that way. I was not able to get it to come out of the nozzle, not even a little to grab with my needle nose. Number40fan, I can try and torch it and see if the bit will pull out with the magnet then or fall out. That's a good idea too and I don't have anything to lose at this point.



  • That's another problem with a Diamond hot end - 3 (or 5) times more likely to get a blockage and it's 3 times more difficult to clear. If you do manage to get it clear, a little tip that I learned is never to unload filament. Instead, cut it off at the extruder and feed the new one in (with the hot end heated) until it comes out of the nozzle. It's a bit wasteful of filament but seems to reduce the likelihood of getting a blockage.



  • That's right, I had never unloaded filament in it since I got it. I would just cut the filament and feed the new through. Didn't have a problem with it being blocked until I broke the bit off in it. I do think though that part of my original problem I posted in this thread was related to a partial blockage since it wasn't easy to insert the bit in the first place. At this point it looks like I'm going to have to purchase a new nozzle or hot end. The whole hot end is $36 on e-Bay or a new nozzle on Amazon is $20. I'm good for an extra $16 to get the extra parts to use for spares and also to not have to do all the teardown and reassembly. I will put heatsink compound around the replacement's heater cartridge though. That seemed to work good as a mod on the original. Thanks for everyone's help!

    John



  • PS - I came up with one more idea to try. A spring loaded solder sucker! I heated up the nozzle, put the sucker (which also happens to have a PTFE tip on it) tight up over the end, pressed the button and it snapped down a little and slowly pulled air in the rest of the way. I tried several more times without it being able to pull the bit down. It also was a good idea, but a no go.



  • At those prices I'd say that you aren't using genuine parts as supplied by from RepRap.me and with genuine E3D heat sinks. TBH and without wishing to cause any offence, that may be why you have problems. If you are interested, I did a bit of write up on my blog on how I assemble Diamonds hot ends. I don't seem to get the blockages or leaks that most people complain about so you might find something useful in what I have written - https://somei3deas.wordpress.com/2017/05/28/how-i-assemble-diamond-hot-ends/


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