Mikey3D
Posts: 12
Joined: Tue Apr 17, 2018 12:45 pm

How to make the stringing stop

Tue Apr 17, 2018 12:55 pm

I bought S3D last week and I'm loving the capabilities but I have one problem I can't seem to solve. The attached shows the problem. I created this simple model to test stringing since I've seen it on my regular prints. The print on the left is from S3D and the one on the right is from IdeaMaker. I've never had a problem with stringing in IdeaMaker but I can't seem to get rid of it with S3D even when I try to set the settings as close to what I'm using in IdeaMaker as possible. The attached was printed with .2mm layer height on both programs with the default print speed set to 60mm/s at 195 temperature which has always worked well for the PLA I'm using.

What I've tried:
Tried setting all retraction parameters the same as IdeaMaker including amount, z-hop, etc.
Tried manual extrusion with .48 (same as IdeaMaker)
Tried extrusion multipliers from 0.9 through 1.0
Tried slowing the print speed down and speeding it up
Tried lowering the temp to 180 even though IdeaMaker prints it fine at 195
Tried the wipe nozzle option
Both programs are set for retraction, 5mm distance, 0.5 z-hop, but I've tried various settings to no avail

None of those make any difference. I still get the same amount of stringing pictured with S3D. With IdeaMaker, I just get no stringing at all, or maybe one or two strands in an entire print at most.

There must be some setting I haven't tried?

Thanks for any help!
Mike
Attachments
s3dstringing.jpg

rrdavis
Posts: 421
Joined: Sat Dec 09, 2017 4:52 am

Re: How to make the stringing stop

Wed Apr 18, 2018 3:38 am

They are totally separate programs, so if you try to just match every setting that isn't necessarily the best idea. You would be best starting with the stock profile that S3D profiles for your printer and then tweaking from there.

Also, there is a lot of good info about this on their quality guide:
https://www.simplify3d.com/support/prin ... -or-oozing

airscapes
Posts: 256
Joined: Tue Mar 06, 2018 10:35 am
Location: Philadelphia PA Area

Re: How to make the stringing stop

Wed Apr 18, 2018 8:16 am

I had issues like that with PLA and bought a food dehydrator and ran the PLA spool in it over night at 140F and once dry, no more strings.. Not saying that is your problem, especially if you can print string free, and then switch to S3D and end up with strings..
Try using the attaches slt to do your string testing, it prints really fast and works well for making strings!
string_test_fast_pyramid.stl
(1.64 KiB) Downloaded 205 times

Mikey3D
Posts: 12
Joined: Tue Apr 17, 2018 12:45 pm

Re: How to make the stringing stop

Wed Apr 18, 2018 9:14 pm

Thanks for the replies. I actually did try with the stock QIDI X-One settings and got the same stringing: that is what prompted me to try to replicate the IdeaMaker settings. But I will say I have to eat a little crow here: I discovered my settings were NOT the same. In IdeaMaker I actually had z-lift (z-hop) turned OFF. Sure enough, when I turned OFF z-lift in S3D, I didn't get any stringing in the S3D print either, and it was a better print than the one from IdeaMaker. And when I turned on z-hop in IdeaMaker, I got the stringing there too!

So I guess that begs the question: why is z-lift actually giving me more stringing and not less? I did google it and found references to the z movement speed being too slow for z-lift during retraction. But I don't know if that's it, or I just need more retraction? I'd like to use z-lift because when I don't, I get some nozzle marks on my top layer when printing a flat top layer. Do you think I need to increase my retraction? I'm using 5mm which was recommended by QIDI Tech for my printer. I could go more but I guess I'm a little afraid that either it'll retract so far that it can't refeed properly or retract so much that the next move won't start extruding fast enough. Don't know if I should go higher than 5mm and try it?

P.S. My filament is about 8 months old. I store it in a drawer with about 8 dessicant packets... but it's still possible that it picked up some moisture?

Mike

zemlin
Posts: 259
Joined: Mon Feb 01, 2016 11:36 am

Re: How to make the stringing stop

Thu Apr 19, 2018 11:54 am

Mikey3D wrote:
Wed Apr 18, 2018 9:14 pm
So I guess that begs the question: why is z-lift actually giving me more stringing and not less?
P.S. My filament is about 8 months old. I store it in a drawer with about 8 dessicant packets... but it's still possible that it picked up some moisture?
Have you ever used a hot glue gun? Every time you lift the nozzle off the part it's going to create a fine string. Having the nozzle wiping across the part without a z-lift keeps it from creating the string. If the nozzle is oozing a bit it leaves the material behind in a thin trail rather than creating a blob. Yes, it can leave a track on the top surface.

As far as storing your filament in a drawer with desiccant ... desiccant only absorbs a limited amount of water. After that it is as effective as a rock. If your filament and desiccant is not sealed in a bag it's doing no good.

Cook your desiccant in a low-temp (150-200F) oven for a few hours to dry it out. Then store your filament sealed in a zip-lok bag or plastic tub with the packets. I also drop a humidity indicator in mine so I know when the desiccant needs to be dried again. The indicator is a paper card with a few blue dots on it to indicate different humidity levels. Those are cheap on Amazon.

Mikey3D
Posts: 12
Joined: Tue Apr 17, 2018 12:45 pm

Re: How to make the stringing stop

Thu Apr 19, 2018 4:01 pm

OK, well it would seem I'm between a rock and a hard place and it isn't software related. If I use any z-lift, even 0.2mm, that gets rid of the nozzle drag on the top layer but then I get stringing. If I don't use z-lift, I get no stringing but the top layer gets scratched by the nozzle in a couple places: looks kinda bad when you print things like drink coasters.

It seems there is no way to avoid stringing and nozzle drag at the same time. I even checked/calibrated my extruder and everything was spot on: not overextruding or underextruding. Micro examination of the layers confirms that the layers look perfect. Only thing I can think to do is do multiple processes in S3D and maybe don't do any z-lift until the last couple layers, then do some z-lift on the top couple layers to prevent the dragging artifacts.

Mike

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DarthRevan
Posts: 459
Joined: Wed Feb 18, 2015 8:29 am

Re: How to make the stringing stop

Thu Apr 19, 2018 4:05 pm

Z-Lift can allow for Ooze, as you're raising the nozzle away from the outline before crossing it. Adding Wipe would potentially then cover discarding any filament left in the nozzle that didn't get retracted with the initial pull of the retraction. Try turning on "Wipe" in the Extruder tab and then turning off "only wipe on outermost perimeters" in the advanced tab.

Mikey3D
Posts: 12
Joined: Tue Apr 17, 2018 12:45 pm

Re: How to make the stringing stop

Thu Apr 19, 2018 4:10 pm

DarthRevan wrote:
Thu Apr 19, 2018 4:05 pm
Z-Lift can allow for Ooze, as you're raising the nozzle away from the outline before crossing it. Adding Wipe would potentially then cover discarding any filament left in the nozzle that didn't get retracted with the initial pull of the retraction. Try turning on "Wipe" in the Extruder tab and then turning off "only wipe on outermost perimeters" in the advanced tab.
Thanks. I should have mentioned that. I tried exactly that. I started with the default 5mm wipe with "Only wipe outermost perimiters" disabled. Then tried 8mm. Still the same stringing. Unless 8mm isn't enough and I should try higher, that doesn't seem to help.

Mike

Mikey3D
Posts: 12
Joined: Tue Apr 17, 2018 12:45 pm

Re: How to make the stringing stop

Thu Apr 19, 2018 9:44 pm

I made a little progress. After watching the preview in slow motion, I discovered that when in wipe mode, it would wipe all the way around the circumference of the string test towers until it got back to the starting point (I'm using the little pyramid test from thingiverse). That's not ideal since it makes a full orbit and ends up back in the "wet spot". I discovered why. I had the option checked to retract when wiping and since my retract settings were 5mm at a 40mm/s speed, it keeps wiping until the retraction is done. So even if I set wipe to only 2mm, it'd wipe something like 8mm. The issue seems to be that since my print speed is higher than my retraction speed, it wipes to 60/40*<retraction distance> before it stops. And if the wipe does a full orbit, it always stops where it started. In essence, since my retraction distance is 5mm, retraction speed is 40 mm/s and print speed is 60mm/s, it was wiping 60/40*5 or 7.5mm regardless of what wiping discance you specify. You could specify 3mm wiping distance and it'd still try to wipe 7.5mm unless (as in the tiny string test towers) it runs out of "virgin" layer to wipe on before it gets back to its starting wipe point: then it just stops where it started the wipe and ends up on a wet spot.

Kinda hard to explain but given my settings, retract when wiping conflicted with the wipe distance. Once I turned off the retract when wiping option, I got the specified wiping distance and if I set it to something like 3mm, it wouildn't make a full orbit around the towers and the stringing was improved because it didn't orbit all the way around to where the wipe first started. It still has stringing on the top half of the pyramid towers where they get really thin, but that's because there's not enough surface area to wipe there. But it did stop the stringing on about the bottom 50% of the towers where they are a little thicker.

I think I'll end up doing like I said previously and just make multiple processes where only the top couple layers get z-lift (to prevent scraping on the top of models). As of now, that looks to me like the only way to have the best of both worlds, even if it's a bit tedious.

Mike

zemlin
Posts: 259
Joined: Mon Feb 01, 2016 11:36 am

Re: How to make the stringing stop

Thu Apr 19, 2018 9:55 pm

Sounds like you might be running a real slow retraction speed. What's that set to?

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