Fixing Z-Hop Stringing

5

I'm printing a model on my Ender 3 in Mika3D Silk PLA, which (just for reference, this is not atypical) has a stated temperature of 200 °C to 235 °C. I have used this filament before and found it works best for me around 200 °C, but was not the case with this print, and I'm wondering what else I can do to fix this issue.

I have retractions enabled, have lowered the printing temperature to 180 °C and decreased the feed rate significantly, to around 75 %. Both of these adjustments happened gradually, making sure there was no change in stringing between adjustments.

I do have rafts and Z hops enabled in Cura, as previous prints of this model were knocked off the base even after leveling the bed properly, and almost every time a "hop" is performed, some stringing occurs. Is there something I can do in my settings, etc, to fix this issue?

Here is an image of the problem. Image of print with stringing

Edit: did some extra research and increased my print speed and switched to a better testing model - same issue.

iPhoenix

Posted 2019-12-16T01:03:52.490

Reputation: 151

1Welcome to 3dPrinting.SE! – Pᴀᴜʟsᴛᴇʀ2 – 2019-12-16T01:20:45.720

1

This is basically a stringing question, these have been asked and answered before, e.g. this answer. Good to see you tried several things like reducing temperature, you should explore the retraction length and retraction speed, increase travel speed and check for possible clogging by cleaning the nozzle.

– 0scar – 2019-12-16T07:03:25.647

Enable “wipe while retracting” will help. – M lab – 2020-05-05T09:49:33.223

1@0scar: While it is a stringing question, the behavior of stringing with z-hop (and a constraint to leave z-hop enabled) differs quite a bit. – R.. GitHub STOP HELPING ICE – 2021-01-03T19:29:03.713

Answers

3

Stringing may depend on sub-optimal retraction settings: when retraction is fast and high enough, the string may be cut and disappear.

You may want to at least try to optimise retraction, at least to exclude that parameter.

There is a tool designed to properly tune retraction: http://retractioncalibration.com/

What it does is print a tower with multiple retractions with increasing retraction distance around the perimeter. Along the Z axis the retraction speed is increased. This tool does not include Z-hopping so stringing may be less visible, but at least you can easily visualise the optimal retraction settings. At that point if the optimal settings are much different from what you had, you may want to try your model again to see if it improved.

enter image description here

FarO

Posted 2019-12-16T01:03:52.490

Reputation: 2 532

1Cool calibration tower, not seen this before! Thanks for sharing! – 0scar – 2021-02-03T23:05:34.887

0

It's because the nozzle has nowhere to wipe itself, like when you don't use Z hop the nozzle wipes itself off in the inside of the print. When you have Z hop enabled the nozzle has nowhere to wipe the string off, which leaves a string when it goes over to the next print. This happens to me all the time.

user20472

Posted 2019-12-16T01:03:52.490

Reputation: 1

0

What improved the stringing issue in my case was increase the amount of retraction on top of the temperature reduction.

After each change, I printed one of these parts (see image below), designed specifically for testing stringing.

stringing test

Nicu Surdu

Posted 2019-12-16T01:03:52.490

Reputation: 311

Can you elaborate on the amount of increase? – R.. GitHub STOP HELPING ICE – 2021-01-03T19:27:08.283

Check http://retractioncalibration.com/

– FarO – 2021-02-03T22:07:39.240