this post was submitted on 20 Apr 2024
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[SOLVED] Trouble with ASA prints (sopuli.xyz)
submitted 6 months ago* (last edited 6 months ago) by [email protected] to c/[email protected]
16 comments fedilink hide all child comments
 

[SOLVED] cause: not enough cooling for overhangs

I increased cooling on overhangs from 60% to 100%, and decreased overhang (10-25%) speed from 100% of outer wall speed to 85%. Issue went away completely and it now prints nicely 👌

I've started printing parts for my voron 2.4, and it's generally going well enough. The parts are looking pretty decent. But I'm having a hard time getting good results with overhanging sharp corners. They tend to warp upwards as seen in the photo on the left side. The prints stick well enough to the build plate and I don't have any other warping or adhesion issues.

Is this because my cooling for overhangs is too much?

I generally print with no part cooling in an enclosure. Temps are 245°C on the nozzle and 105°C on the bed, using 60° fan speed for overhangs. I'm printing on a anycubic kobra 2 with azurefilm ASA.

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[–] [email protected] 5 points 6 months ago (3 children)

Try with fans disabled or slowed down and enable draft shield in the slicer. Ideally the printer would have a 60-100°C heated chamber.

[–] [email protected] 4 points 6 months ago (1 children)

100* in a chamber? Are your steppers rated for that? I’ve never went above 45

[–] [email protected] 3 points 6 months ago

Place them outside the heated chamber.

For motors, the limit is the wire insulation so might get away with 100°C ambient. If you can't move them out there are also water-cooled extruders: https://www.dold-mechatronik.de/mebs-Hemera-WaCo-Mod-EN

[–] [email protected] 3 points 6 months ago (1 children)

The solution was more cooling. It was warping due to too much heat, I increased cooling to 100% and reduced overhang speed slightly and it now prints well.

[–] [email protected] 3 points 6 months ago

Printing fast/without cooling can also go the other way:

By printing very fast the last layer may still be "hot" when the new layer is added. As the temperature differential is smaller there is less stress within the part once it is cooled down.

[–] [email protected] 2 points 6 months ago* (last edited 6 months ago) (1 children)

Fans are completely disabled, except for overhangs and bridges. If I disable fans for overhangs and bridges, they sag like crazy.

I doubt draft shield is going to do anything, the printer is already completely enclosed in a tent. I have around 50-55°C inside the tent.

Edit: I tried a re-print with less cooling for overhangs, it seems to exacerbate the issue significantly.

[–] [email protected] 2 points 6 months ago

If your tent truly is that hot I'm impressed. On my 2.4 with just 2x bedfans, the chamber doesn't crack 40 degrees C after 45 minutes.

The reason why most recommend low/no cooling for ASA/ABS is due to low chamber temps.

If your chamber is that hot you should be able to crank the cooling without much concern. Print a temp tower to prove it out, and to feel out of this is a filament temp issue.

One other piece of advice for ASA: I've found that it likes consistency. I print basically all features at the same speed, other than the first layer. I suspect cooling would fall into this category too.

[–] [email protected] 4 points 6 months ago (2 children)

I printed all my parts on my old i3 clone inside a couple of cardboard boxes taped together. They weren't pretty, but they were pretty functional. I did reprint my stealth burner and it looks a ton better than my first part, but in terms of function there isn't a whole lot of difference. The nice thing with plastic is that you can always mechanically trim material if needed. Most of the Voron parts are pretty forgiving too and don't have super critical dimensions.

As for why your overhands are warping up, it's likely your cooling as you guessed. ASA does not like big thermal gradients and fan + passive chamber heating will result in that. I printed basically all my parts with zero cooling and didn't have any real issues other than the stealthburner. On that note, plan to print bedfan mounts at a minimum. Something like the filter is nice to have if you plan on printing much ASA or ABS. If you're building a bigger 2.4 you might want both...

[–] [email protected] 2 points 6 months ago

Definitely recommend checking out the nevermore max. i built the beta max and even with aquarium carbon it's massive how much less odors my abs prints produce. Any sort of recirc filter is a good idea, I just like not having to change the filter media for a while.

[–] [email protected] 2 points 6 months ago* (last edited 6 months ago) (1 children)

Wow yeah that first one is pretty terrible looking 😅

I'm decently pleased with mine though, but I'm really looking forward to the quality on the voron. I actually already have "the filter" on my current printer (slightly oddly placed in the tent, but it works), and I just connected it directly to the printer PSU and manually turn it on/off with a toggle switch.

[–] [email protected] 1 points 6 months ago

Very nice! My i3 clone was over extruding quite a bit in hindsight. It also has a non-gear reduced extruder, which results in a lot of extrusion artifacts :(

[–] [email protected] 2 points 6 months ago

You need quite the opposite, more cooling on those overhangs. As you are in the chamber, the heated air wont cause warping like outside an enclosure, so crank those speeds on overhangs. I generally run 80-100% on bridges anf steep overhangs. I do also slow down print speed on overhangs significantly to allow more cooling aswell

[–] [email protected] 1 points 6 months ago (2 children)

May I ask is ASA better than ABS for voton parts?

Sorry OP, cant help with your problem, never printrd ASA

[–] [email protected] 3 points 6 months ago* (last edited 6 months ago)

Both ASA and ABS are approved materials. ASA has higher heat defection than ABS, should be easier to print and it smells significantly less when printing.

[–] [email protected] 1 points 6 months ago (1 children)

To add to OP's reply, ASA filament also tends to be higher quality, like more consistent diameter etc

[–] [email protected] 1 points 6 months ago

Good to know thx. Its been a long time since my last ABS print and I was just going to order some, but I guess ill try ASA this time