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Delta ABS parameter issues.

Posted by Qdeathstar 
Delta ABS parameter issues.
September 24, 2016 04:00PM
Lately I been experiencing these lines/zits on my prints.. That seem to happen one one side or the other of the print at random, and if I'm printing multiple objects at the same time, the zits still appear, but they'll be on random layers (eg, not all the same layer)

So far I've tried cleaning the nozzle by removing it from the hot end and soaking in abs/torching it... It's compleaty clean and that seemed to help filament flow, but not this problem.

I've also tried lowering retraction speed but didn't seem to make a difference at all. Any ideas?

Re: Delta ABS parameter issues.
September 24, 2016 05:59PM
there are a few possibilities, more and clearer images would help I cant really see what is going on there. I get similar looking issues to the image posted from a travel move and oozing laying a string of little beads and the string moving with the nozzle until it encounters a feature that grabs it, resulting in the string of blobs being on the side of a wall or causing a layer to print badly from being in between layers. But the image posted is not clear enough and more angles to see depth or height of surface defects and position within the geometry would help.

if your slicer has a path preview, compare the position of defects to retractions and travel moves. this may show you clearly what is causing what.
Re: Delta ABS parameter issues.
September 25, 2016 01:44AM
Thanks for your reply Milton.

Here are some more pics:

Re: Delta ABS parameter issues.
September 25, 2016 01:45AM
I also printed a calibration test.... The circle cut out is more like an oval....

Re: Delta ABS parameter issues.
September 30, 2016 01:42PM
Could it be something related to z movement and layers being squashed by not moving sufficiently in the z direction this might push filament sideways. Would explain the oval circle too, thought it could just be where it's struggling with the overhang.

Slack belts? Or something too tight with too little motor current.

Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Re: Delta ABS parameter issues.
October 01, 2016 02:50PM
All good things to check.

Hi Qdeathstar!
It looks maybe like inconsistent extrusion to me, just a guess at this point. I was looking at one photo, and the perimeter started out fine and then died. I look for where the problem starts.

We'll need to know a few more things like these to help you. The more info you can provide, the easier it will be to help determine the problem since there are a lot of things in combination that can cause this. (If it's what I guess it is).

I've had about all these problems (I went the hard way and built both my extruder and hot end) so I think I'll make the following the start of an Inconsistent Troubleshooting Extrusion Guide, similar to this one.

For now, wild guesses follow:
  1. Print temp too low. The setting depends on your thermistor and hot end configuration. For mine - with a large bore, and the way it's measuring the temp - I find 245 is a minimum for ABS, and print at 260.
  2. Extruder gear clogging
  3. Extruder missing steps due to low driver current - it may stall or kick back.
  4. Extruder missing steps due to high driver current - the driver overheats and resets for a short time.
  5. Extrusion rate too high for the max rate achievable at the current print temp for that hot end (extruder will stall, grind, slip, or skip back)
  6. Not enough pressure on the compression bearing
  7. Too much pressure on the bearing - causing flattened filament. (Make and use a contoured bearing)
  8. Inconsistent hot-end temp due to PID settings
  9. Thermistor not seated properly in hot end, or thermistor wiring issue, or electrical interference.
  10. Hot-end has trouble maintaining temperature under load due to too low power supply voltage
  11. A fan is blowing on the hot end and cooling it. (Move/duct the fan, insulate the hot-end).
  12. Wild swings in nozzle pressure due to print speed/perimeter width/layer height changes between features - causing the extrusion to stall.
  13. Excess friction in the bowden system
  14. Sharp bends in the bowden at some X/Y positions
  15. Wiring issues to extruder motor
  16. Electrical interference - motor wiring not shielded
  17. Inconsistent filament shape - a wide spot jams the hot end
  18. Debris in nozzle
  19. Bad driver
  20. Bad extruder motor
  21. Loose grub screw on extruder gear. Grind a flat on the shaft and use nail polish as a removable thread-locking compound.
Someone kindly remind me if I've forgotten something.

There are ways of troubleshooting each of these issues, it will just be much easier with more info. Hope that helps.

Edit: added #21.

Edited 1 time(s). Last edit at 10/02/2016 12:28AM by Paul Wanamaker.

My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
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