RE: Stringing Issues
Yeah I’m printing at about 200 c for PLA, seems like this is a fix along with software updates.
wouldn’t 0.6mm print faster than 0.4mm though? Or is that just for ooze prevention?
RE: Stringing Issues
Jury's still out on that one. 0.6 came relatively late in the development and I'm really uncertain if the melt zone of the hotend is good enough to really exploit the larger diameter. Theoretically you can print fatter lines and higher layers with 0.6, but for that to translate into speed you also need to be able to melt the necessary filament volume reliably. It might turn out to be better to run 0.4 at higher speed, but afaik nobody has tested this systematically.
RE: Stringing Issues
Hmmm I see, guess we’ll do with temp adjustment for now
RE: Stringing Issues
I would like to use the Temp Tower you used. Would provide a link to an XL temp tower?
RE:
Before I start: The mystery to me is that I have zero stringing when printing with one color. Temperature does also not make a difference here (e.g. 220C works just fine).
For multi color print I have tried many things:
- I have done the nozzle seal calibration (tried a few things there)
- I used the "Dog Video" which defintely improved, but I still have stringing
- I have tried to use - or not - the wipe tower. Note: The idea of the wipe tower is - to my knowledge - to get rid of the remainder of the filament for printers with only one printer head, so it is a mystery why this is required. BUT Yes, with a wipe tower the result looks much better. Funny enough: I see even stringing between the wipe tower and the model with many strings > 10cm of length - which is odd?
- I reduced the retraction speed as suggested on both heads - from 35mm/s to 25mm/s - with no (big visible) effect
- I tried to vary the temperature of the filament. I was going even so low that you could see that the print quality was starting to suffer (happened for me at ~205C). Best results were found at 222C(first), 212C(follow)
- Played around with some other parameters - but no success there.
- Open is the question of humidity (ordered a de-humidifier / heater for the filament to try that, but as I have just pulled the new filament out of the bag, that feels like a straw for me.
So - what I have seen (and that matches the result) is:
- Printing single color is producing awesome results, no matter the temperature. Tried that with all filamanets and all heads and the result is always great.
- When looking at the model, I see A. some "color splotches" from the wrong color in places (sometimes they can simply be wiped off, or using a finger nail), B. I see strings inside and outside of the print (so produced after the head change - OR - while the print within the model while hopping from place to place (benchy3D) is going on(!!), C. I see strings which are short and extremely fine as well as long and thicker (which means more filament is involved), D. I have seen that after printing another single colored model later on, the first layer had a chunk of "filament dirt" on it. I can send a picture if that helps.
So the way I see it is that for what ever reason the printer must be leaking filament waste when printing with multiple heads, which does not happen when printing with one. So either nozzle seals - or - something happens to the other heads while they are waiting for their next round (like e.g. higher pre-heating while waiting for their turn) which would explain the phenomen that more long strings are getting produced if there are multiple layers of no action for one head - can send a picture) - or - some parameters are simply different when using multiple heads.
Anyone any thoughts?
RE: Stringing Issues
This is what I use as a base:
https://www.printables.com/model/504263-prusa-xl-temp-tower-for-pla-petg-abs
But better slice it yourself, your nozzles and quality settings might differ.
I would like to use the Temp Tower you used. Would provide a link to an XL temp tower?
RE: Stringing Issues
Thanks
RE: Stringing Issues
The mystery to me is that I have zero stringing when printing with one color.
Did you notice the "idle" temperature for the filament when it's waiting to be used? That temperature can cause all sorts of stringing glopping problems. This temperature is controlled by the custom gcode part under the slicer's printer settings. I've found it to be way too high for some filaments. That's the variable here that may be causing your stringing effects. What filament are you using?
RE: Stringing Issues
yeah the bed probing temp by default is WAY too high for any of the flexibles I've tried. It's 210 by default. I set it to 175 so it doesn't leave globs on each bed leveling probe location. I think I need to lower the idle temp for a few of the ones I use too. ninjaflex is pretty good at this point but my sainsmart needs a little tuning I think,
RE:
I get occasional blobs sticking to the silicone wipers when the tool returns from park. I think these just collect there while it cools. It's not much, and it doesn't always happen, but at least in my case it's what's causing stringing/globs in multicolor prints.
Since my wipers are aligned (I think) correctly, and my filament doesn't drip at all at the idle temperature (170 in this case), the only solution I see to this is installing nozzle brushes.
But I have to say with PETG and PLA after dialing in the temperatures, it's near perfect already. The only remaining problem is when I get just one tiny ugly spot on the front face of an otherwise beautiful print.
RE: Stringing Issues
I use nozzle brushes and I highly recommend them. They should be standard on the XL.
RE:
Planning on installing these tonight: https://www.printables.com/model/678695-nozzle-wiper-brush-pre-leveling-prusa-xl and https://www.printables.com/model/678703-prusa-xl-tool-change-wiper-brush
Not a big fan of rubbing brass wire over brass nozzles.
RE: Stringing Issues
I've been using these with the nylon brushes for weeks now. they work well
https://www.printables.com/model/677226-prusa-xl-nozzle-brush-scrubber-remix
RE: Stringing Issues
Toothbrushes are also made from nylon 😉
TBH I went with the Bambulab things because I thought they looked cool and are designed specifically for this purpose. I'll swap if I find they need to be replaced too often.
RE: Stringing Issues
the nozzles aren't in contact with them log enough to really melt them. and you don't have to do any custom gcode to use them, they just naturally pass over them when they docked/undocked. they definitely help though.
RE: Stringing Issues
I've had issues with a glob of filament wrecking the bed probing and subsequent first layer. My tactic has been to stand by and brush the nozzle myself when it comes to the front to do the home thing. The brush mounted on the back idea is great! I just ordered some brushes.
RE: Stringing Issues
They really work well. it's less custom gcode for me to remember to add when I create new projects.
Kudos to @baconfase and the original author he remixed from
I've had issues with a glob of filament wrecking the bed probing and subsequent first layer. My tactic has been to stand by and brush the nozzle myself when it comes to the front to do the home thing. The brush mounted on the back idea is great! I just ordered some brushes.
RE: Stringing Issues
One thought from Unicorn3ds post…
You never stated your settings for “Retraction on tool disable” per extruder.
If you don’t retract out of the melt zone when the tool is parked you will get stringing no matter what you do. You have to retract at least 11.7mm.
RE: Stringing Issues
For the tpu, I've not changed this setting from whatever the default was. I've only changed the amount for retraction and the retraction speed. When you mentioned it in another thread I did play with it for some soluble filament. I figured for flex the less I'm retracting the better.
One thought from Unicorn3ds post…
You never stated your settings for “Retraction on tool disable” per extruder.
If you don’t retract out of the melt zone when the tool is parked you will get stringing no matter what you do. You have to retract at least 11.7mm.
RE: Stringing Issues
Many thanks for the hint! I will give it a try! I use MatterHackers Build. I have found that it seems to work best at 212C and 205C is too low.