Printing problem with E3D V6 Titan Bowden

Discussion in 'Calibration, Help, and Troubleshooting' started by Tony Sun, Jan 17, 2018.

  1. Tony Sun

    Tony Sun Active Member

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    Hi all, about 2 months ago, I finished my HEVO, but since then I have printed over 20 benchies and just couldn't get a proper print. I recently got S3D to help with that, but only small improvements. I am using a E3D V6 hotend with Titan extruder with Bowden setup on my Hypercube Evolution. The problem I have as you can see in all the pictures, along with my settings in S3D in this dropbox folder. It seems to be a retraction issue as you can see the same part always seems to "underextrude", but it's not, and there's alot of retraction there. my ptfe tube is about 350mm long (Right around the tip of the boat and the middle of the rudder area is the problem area as you can see in the pictures)

    Here is my dropbox folder, any help would be greatly appreciated!
    https://www.dropbox.com/sh/vsq7pi12jvsdzsz/AAB4uzXEPoKKgrPROwdg9NZSa?dl=0

    EDIT: I just realized I'm an idiot and posted in the wrong area >.< Please move this to either the E3D V6 or Titan section please, thank you very much.
     
  2. dc42

    dc42 Well-Known Member

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    For the first set of prints, I think you have retraction correct (I anticipate that with a 350mm Bowden rube you will need about 4mm, or a bit lower if you use pressure advance in your firmware) but the print temperature is too high and/or you have insufficient print cooling. Does your printer have a print cooling fan?

    For the second set, you have insufficient retraction (hence the zits on the hull) and it shows even greater signs of printing too hot.

    You have "Adjust printing speed for layers below" set to 3.5sec and 50%. I suggest you change that, e.g. to 5 sec and 20%, otherwise you will have problems with the smoke stack..
     
  3. Spoon Unit

    Spoon Unit Well-Known Member

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    I use 15 seconds and 20%, just to give another data point. You don't mention what you're printing. I assume it's PLA from the printing temperature, but would be good to confirm. If so, you might be able to drop the temp further. Depending on the brand I've printed PLA as low as 185. dc42 asks about cooling; you didn't show that panel from S3D. For a benchy, I'd recommend using 100% cooling from about layer 3 upwards. This might be an issue for your hotend maintaining temp, and if so, either lower the cooling on lower levels and increase to max by about layer 15 once the reflected wind is sufficiently far away. Another alternative is to use a silicone sock, at which point you can use 100% cooling right from low layers.
     
  4. Tony Sun

    Tony Sun Active Member

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    Ah right forgot to mention the material again, it's Zyltech PLA, oh wow okay I thought 200 was low, okay I'm at work right now, but I will definitely do as you all said and try it. I have print cooling on the fan and silicone sock on the hotend, I'm using the half circular filament shroud provided by one of the members of the group. I will try those settings but what I can say is this, at those area where there is "underextrusion", the thing retracts and afterward, no filament comes out, which I believe means it's stuck in there?, and doesn't return to normal until higher levels. Will test later today and report back!
     
  5. Spoon Unit

    Spoon Unit Well-Known Member

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    I've never had success with Bowden delivery myself, and I now suspect that was because I never took into account the slack that would be generated in the tube. I believe anything you can wangle to reduce the tube length is also going to contribute positively to repeatability.
     
  6. Tony Sun

    Tony Sun Active Member

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    Alright here are the newest results, it's still the same layers, just a little better, however what I notice is this. During these problem parts, the Titan would "click" and I'd see the filament snap, which means it's being pulled too far that it snaps back and gear loses slip on filament I believe, which means I guess I can't use that high retraction distance? Should I turn on only retract on open space and experiment with Wipe /Coast even though E3D themselves advise against it?

    https://www.dropbox.com/sh/hn7pnzwdc7z919a/AADeA0og9blW-JAIifrWGyF4a?dl=0
     
  7. Tony Sun

    Tony Sun Active Member

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    Did another test, the only settings changed were from outside in to inside out printing, retraction to 5.5mm, retraction distance 45mm/s, multiplier 0.92, temp at 185 still, and checked Only retract when crossing open spaces. I'm literally on the verge of crying/pulling my hair out, $600 machine and can't print... T_T always the same layers... (oh and also adjust printing speed for layers below increased to 11 secs.)

    https://www.dropbox.com/sh/zbrmunyi4r1wm79/AADow8qXoRd2IUZDAoVIf2gTa?dl=0
     
  8. Spoon Unit

    Spoon Unit Well-Known Member

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    Welcome to the world of 3d printing. It's frustrating, but very rewarding. You'll feel like a genius if you get through this.

    So, your latest results look pretty good. I'd say you're under-extruding there. Either slice with a little over extrusion or tune your esteps. Inside to out is what I use.
     
  9. Tony Sun

    Tony Sun Active Member

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  10. Spoon Unit

    Spoon Unit Well-Known Member

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    That looks a lot better. The first layer is well defined. You can see where the print begins and it takes a while before the flow gets fully going, so if you can tune an initial push of a little more material that could help. In S3D this is called Extra Restart Distance. On the other hand, maybe you're starting the print right there with no priming? If so you could try a skirt in order to get the nozzle primed before you start the first layer. That said, the small uprights on the cabin are the weakest part. You might want to try a print with no retraction at all to see how that fares, at least to get a comparison and more input.

    How long is the bowden tube?
     
  11. Tony Sun

    Tony Sun Active Member

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    Hmm that's a possibility, I do prime but I think not enough, will try to fix that. I'm trying 0.2mm extra restart, I do print a brim though so I'm wondering why it looks like it's not extruding enough. I have already tried a print with no retraction, and it works on those areas, just lots of blobs and stringing, so it's definitely a retraction issue.

    The Bowden tube as stated in the first post is about 350mm long (sorry I said PTFE),

    Here is another update on the settings and print, it still looks like the top is underextruding, but I'm already at 100% and I have calibrated my extruder to do 9.97mm on 10mm.

    https://www.dropbox.com/sh/yymbr72uec3fcy8/AAC64j3KL5DbNIqpWYgrQ_dxa?dl=0
     
  12. dc42

    dc42 Well-Known Member

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    If the under extrusion is only or mostly on the bottom later, that could simply mean that your initial Z=0 nozzle position is a little too high. If the under extrusion is present on top solid infill too, don't be afraid to increase the extrusion factor, either in the slicer or in the printer controls if it has that facility. Once you have found an extrusion factor that gives good results for that reel of filament, write that value on the reel.
     
  13. Spoon Unit

    Spoon Unit Well-Known Member

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    Oh, also, in your slicer, don't just go with 1 solid top layer, if that's what you're doing. A bare minimum is 3, and I tend to use 4 to make sure.
     
  14. Spoon Unit

    Spoon Unit Well-Known Member

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    One more thought. Print in different orientations and different positions on the bed again to get yourself some more data.
     
  15. Spoon Unit

    Spoon Unit Well-Known Member

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    You say you've calibrated your extruder to extrude 9.97 on 10. I'm not sure if that means you ask for 10 and get 9.97 or ask for 9.97 and get 10. As dc42 points out, you can always deliberately miscalibrate it to ensure slight over extrusion. So, in that case you want a situation where you ask for 10 and get 10.5 (5% over) or 11 (10% over).
     
  16. dc42

    dc42 Well-Known Member

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    I find that every reel of filament has a slightly different ideal extrusion factor. There are at least two causes of this:

    1. Variations in the filament diameter;

    2. Variations in the amount of die swell you get when the filament is extruded. This depends on the chemical makeup of the filament, and probably also how much water it has absorbed.

    Some people suggest that you should measure the filament diameter at several places and in different directions, and enter the average value in the slicer. That's too much hassle for me, and I prefer to keep the same slicer settings whatever PLA filament I am using. So I do a small test print with each new roll of filament, adjusting the extrusion factor in the web interface during the print to get the best results, then using that extrusion factor for all prints using that roll of filament.
     
  17. Tony Sun

    Tony Sun Active Member

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    hi Spoon and dc42, thanks for helping again, when I want it to extrude 10mm it gets 9.95-9.97. The newest test is at 6mm retraction, 0.4mm extra restart distance, with top layers at 4 as Spoon said, with extrusion multiplier at 1.06 (106%), the top and bottom layers are now fine, but it got little jams at the same places again, and the smoke top started fine, but halfway through I heard the titan snap when it pulls back, and then nozzle stops extruding cause it's jammed.

    So it seems like 6mm is too much, but 4mm distance causes the same thing. 5.5mm causes more blobs on the inside of the bridge. Should I try 5mm retraction distance? or somehwere between 5 and 5.5mm? and faster retraction speed? (currently at 45mm/s)

    currently at 190C.
     
  18. dc42

    dc42 Well-Known Member

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    I reckon on using retraction of just under 1% of the Bowden tube length + 1mm, no extra restart distance, 60mm/sec retraction speed and retraction acceleration as high as your extruder drive can manage. Reduce the retraction if you are using a narrow bore Bowden tube (1.8mm instead of 2mm) or you are using pressure advance. Pressure advance helps to get even extrusion, especially on Bowden systems.
     
  19. Tony Sun

    Tony Sun Active Member

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    Okay I will turn on pressure advance on my Duet Wifi, then try the 60mm/s retraction speed. Acceleration for my Titan is at 250mm/s^2, is that too low?

    I remeasured my bowden tube and it's actually 380mm, so probably 4.6 to 4.8mm retraction distance according to your formula dc42.

    For the pressure advance, is this a good starting point like on the wiki?
    M572 D0 S0.1
    and do I just put it anywhere in the config.g file?
     
  20. Tony Sun

    Tony Sun Active Member

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    Hi dc42, tried the settings above, with 4.8mm retraction, 60mm/s retraction speed, with pressure advance. Results were even worse, starting jamming right when it started to print the holes on the bow, along with the filament snapping on the Titan. Temp was changed to 185, so maybe that's too low?

    EDIT: Prior to this, I had did a print at 5mm Retraction Distance, 45mm/s retract speed, 0.40mm extra restart distance,1.08 extrusion, and that actually came out pretty well, the smoke stack actually was printed well. Pressure advance was off.
     
    #20 Tony Sun, Jan 20, 2018
    Last edited: Jan 20, 2018

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