Stringing/Retraction Issue - hours of trial and error

Twert 2017-12-02 06:13:14 UTC #1

I've had a prusa 2020 i3 for several months now and I've been able to get most of the calibration in. Recently I was trying to print the Iris boxes that are on thingiverse but haven't been successful. I thought that stringing may be my issue so I have been running this retraction test over and over again:
https://www.thingiverse.com/thing:909901

I have been able to improve results by increasing my retraction and by decreasing my temperature, however I'm still not happy with it. My temp is currently very cool - probably too cool so it may not be reading correctly. I'm currently printing at 175C with a 3mm retraction and I still get stringing and lines of deposited filament on 1 side of the retraction test object - only one, not the other three. The heavier bands seem to be small amounts of filament that get deposited as the nozzle travels in that area. I can't get rid of them. If I go any lower in temperature my printer stops extruding.

Any ideas or suggestions?

csorrows 2017-12-03 23:07:23 UTC #2

To work on finding a solution, we need to know what slicer you are using so we know what settings you have available to you.

Twert 2017-12-04 02:01:35 UTC #3

Using Repetier V2.0.5 with Sli3er V1.3.0

csorrows 2017-12-04 15:04:16 UTC #4

Hopefully someone else chimes in, I have never used RH or Slic3r. Sorry.

mriley 2017-12-18 14:41:54 UTC #5

I know this is a couple weeks old, but wondering if you found a solution to this? What layer height are you printing, and have you tried another filament?

It seems odd to me that you're still getting that much stringing at 175C. If another filament does the same, I'd double check the temp of the extruder with a reliable IR thermometer or a multimeter with a thermocouple to rule out an issue with your thermistor.

BobC 2017-12-18 17:40:49 UTC #6

Print a temperature calibration tower to determine the flow characteristics of your filament (https://www.thingiverse.com/thing:1298948).

I do this for every new spool. And repeat it when things go weird (such as due to the arrival of cooler weather). The key thing to know is that neither the "actual" temperature of the nozzle nor the "indicated" temperature matter at all! What matters is that the filament prints well (whatever setting is needed), and the tower makes that happen. In the case of my crappy 101Hero, the hot-end temperature indication was way off, and the firmware wasn't released so I couldn't update the conversion constant, but I get great prints working from the temperature tower.

I also do a speed calibration tower (https://www.thingiverse.com/thing:1381839) whenever mechanical issues arise (which can also be due to ambient temperature changes).

I keep an old install of Cura 15.04.6 around just for printing these towers, so I can avoid affecting other projects. I print the towers using "draft mode" (high speed, thick layers), since printing slower with thinner layers can hide some issues. Also be sure to slice with no more than two bottom layers, single wall, no fill, and no top layers, to make the prints as fast as possible.