pls help......the stringy problem keep driving me crazy......

Hi everyone, i am a beginner and wish to learn from you guys

i don't know why all prints my delta bot made are stringy, i have browsed the help\info as much as i can, and did tests as many as i can, i almost wasted a roll of filament but still haven't resolve this problem.

below is the setting:

slicer: cura\slic3r (tried both)

nozzle size: 0.35
filament: PLA 1.75
layer height: 0.2
horizontal shell: 0.7
bottom\top thickness: 0.4
fill density: 40%
printing temp: (tried 180-230, tried 5-10 increment on a few layers)
bed temp: 60
bed: glass(adhesive is good)
fan: full
flow: 100%

retraction speed: tried 60-150
retraction: tried 5-8

speed: all speed tried 30-90
travel speed: tried 100-150

i have tried checking the 'wipe when retracting' option in slic3r, if the layer includes filling in it works ok, if the layer doesn't include filling in (such as, a wall) the problem still exists

please see the attached pics for my problem

can it be a problem on filament or nozzle? i almost lose hope and wish somebody can help, thank you very much in advance

Quote
bluesduff
retraction speed: tried 60-150
retraction: tried 5-8

That looks a whole lot like the problems that I was having with insufficient retraction, but your settings are in line with what works on my printer with no special wipes or anything.

The only thing that I can think of is to check the acceleration setting on the extruder. Perhaps it is limiting the retraction speed? If you are using Smoothieware, a potential gotcha is that they use mm/minute and not mm/second in a few settings...so you need to pay attention to the units or you get really skewed results. Another thought is that the extruder may be missing steps in retraction due to the stepper drivers not being tuned.....

When I was having stringing problems on my Ormerod (a Cartesian printer with a 400mm Bowden extruder tube), I found that avoiding stringing was down to two things:

1. Retraction. I found 4mm sufficient, at speed 3600mm/min and acceleration 1000mm/sec2.

2. Temperature. Too high and I got stringing, too low and the print would fail for other reasons (probably because of lack of adhesion). I settled on 195C for the first layer (to help with adhesion to the glass bed) and 185C for subsequent layers.

I am using the same values on my Mini Kossel, and I get slight stringing sometimes. I will try a lower print temperature (because it uses a different hot end) and a little more retraction (because the Bowden tube is longer).

Edited 1 time(s). Last edit at 02/28/2015 10:25AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].