2
$\begingroup$

I have a Wanhao Duplicator i3.

I have done many excellent prints with this printer, and have first hand experience that it can do a pretty much flawless print.

But... Recently, I am experiencing weird results. My "flow" seems uneven. When laying down the first layer of the raft, I can see it looks like it "beads" in some places. Thin lines with little "beads" here and there (which seem to be in a constant pattern) i.e. -------()-----()-----()------()------ etc.

I initially thought, wet filament... But drying the filament had no noticeable effect. Further more, all my prints seem to be horribly laminated at a certain "height" of the print. This is really strange as it will print perfectly and only at a certain height, mess up about 5mm of layers (height wise), and then print great again. This seems to be a constant now.

I dont understand how/why this could happen, as the whole z-axis is on a linear spiral shaft. Unless there is a gcode issue somewhere that I am not aware off. I am using CURA as my slicer and I feel that even if there was an isnturuction hidden somewhere at a certain height, it would possibly effect a single layer, and not 5mm worth of layers.

Any ideas?

I have tried:

Different filament Pushing flow % to 105 and 110% respectively Cleaned extruder gears and print head Oiled z-axis shafts

What baffles me, is the weird delamination (or rather lack of lamination) at a certain height. I have not measured this height exactly, but from guestimating, it looks like roughly the same height on every print where the issue is visible (about 3/4 up in the attached image). My support structures are also VERY messy, whilst they were very precise and perfect previously.

enter image description here

Thanks

$\endgroup$
  • 1
    $\begingroup$ Looks more like retraction issue. Need more data: 1) print retraction settings 2) heatbreak radiator temperature (should not be more than warm) 3) can you hear extruder motor clicks during the print? $\endgroup$ – Mikhail Z Mar 2 '17 at 21:16
  • $\begingroup$ Looks like either a retraction problem, or a heat setting issue. There could also be some buildup in your nozzle, but more than likely it's one of the first two. $\endgroup$ – Diesel Mar 5 '17 at 14:45
1
$\begingroup$

This looks like a heating or retraction issue. I also have a Di3, and I encountered a similar problem a while ago. I have found that leveling the bed very well and making sure the z-axis is aligned fixes most problems with this machine. Re-calibrate your printer and try out a different slicer. This link from the 3D Printer Wiki is very useful.

| improve this answer | |
$\endgroup$
  • $\begingroup$ Thanks, I have had better results with a higher printing temp, but it still shows every now and again. I will try the z axis squaring.. its easy enough to do frequently. I cant see it being a retraction issue, as that would manifest itself through the whole print, not just certain heights? $\endgroup$ – Louis van Tonder Mar 13 '17 at 8:53
1
$\begingroup$

I had a similar problem with my prusa i3 variant i built. I found that this issue would decrease in occurance when retraction was disabled however would not completely disappear.

After much experimentation I found this to be a feed issue with the extruder. In other words the filament was not being pushed hard enough to the teeth of the hobbed bolt to have enough traction to pull the filament down as fast and easy as the extruder would to pull the filament up during retraction. Even without retraction enabled, my extruder's drive gear teeth would not dig deep enough into the filament to pull a consistent amount of filament for the same x amount of distance per instances of a similar timeframe.

Essentially because retraction speeds are much faster than normal extrusion and there is not enough force required to retract compared to having to pull filament from the spool the retraction and extrusion settings would yield results that do not match actual expected filament travel distance.

My recommendation in your case:

1) tighten your extuder idler so it puts more force on the filament. What might appear tight to you does not necessarily mean is tight enough for consistent pull. If yours uses the two long screws on springs for force maybe consider getting longer and tougher springs.

2) Be aware of your extrusion steps/speed. You don't want to grind your filament when retracting.

| improve this answer | |
$\endgroup$
1
$\begingroup$

Thanks to all the replies. Whilst all of them may be valid in some scenarios, my case seemed to have been a combination of things, that relates to most of the replies here.

I had my spool holder on the side of the machine, and I noticed some friction as the filament feeded over the "arm" on top of the printer into the extruder. I sat and looked at this for a while, and it seemed apparent that as the extruder moves up, the angle of the filament over the "guide arm" on top changes to a more severe bend. This may have been why it always battles to extrude nicely at a certain height, and then maybe recoveres after that to an extent. (SO yes, under extrusion may have been the issue)

I have now moved the filament to on top of the printer to feed straight down. I have also slowed down the travel to about half of what it was (40 now, was 60). I also dropped the infill speed a bit as that was also a mess most of the times.

So far I have had excellent results! I am not sure if its the travel speed drop or the extruder feed that helped the most, but I am a happy chappie again. (So far).

Thanks for all the input. It really made me re-look at all of this from a different view.

| improve this answer | |
$\endgroup$
  • $\begingroup$ I have experienced similar issues with my cartesian printer. In my case, the force required to pull the filament from the spool was too great - on one occasion, the spool spindle was stuck so badly that the holder gave way and the spool crashed into the printer. After several iterations of spool holders, the problem is now gone for good. $\endgroup$ – vwegert Mar 20 '17 at 5:41

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.