ABS Woes - Need Assistance (pics attached)

Filament
1

Hi gang,

As I’ve mentioned before, I’m new to 3D printing as of last week, and aside from my initial octopus test print, I haven’t had what I would consider a successful print since. Very frustrating. I’m hoping the community experts can help me trace down the issue(s) and help me resolve them.

Here’s what I would like to know for each Exhibit.

  1. What is common terminology for this particular phenomenon?
  2. What’s likely causing it?
  3. How do I resolve or mitigate the issue?

My specs for these prints:

Lulzbot Mini
.5mm extruder
ABS (IC3D High Quality Green 3mm ABS - http://www.amazon.com/gp/product/B00TVL4R2G)
Extruder temp: 240C
Bed temp: 110C
Fan: Off
Slicer: Cura
Settings: Usually the default “high quality” setting or a slight variation of that

EXHIBIT A
(http://www.thingiverse.com/thing:901128)

IMAGES
https://goo.gl/photos/7RMmkAbxAosPdzFP6
https://goo.gl/photos/XcpATBuw8WPDJ2u56

The top 75% of the print looks amazing. If the entire print looked like this I would be ecstatic. What’s going on in the first layers!?!


EXHIBIT B
(http://www.thingiverse.com/thing:359008)

IMAGES
https://goo.gl/photos/bXrB1oWqcKg93VQ67

Bridging looks terrible from the bottom up. The other side towards the top of the model the bridging looks better but still not great. How do I resolve this without bracing? This model was specifically designed not to need any bracing.


EXHIBIT C
(http://www.thingiverse.com/thing:359008)

IMAGES
https://goo.gl/photos/exqfKES2KH6V3rhx7
https://goo.gl/photos/9VAsNcLXRGGecW8h7

The bottom side looks uneven and rough compared with the top side. What’s going on here?


EXHIBIT D
(http://www.thingiverse.com/thing:359008)

IMAGES
https://goo.gl/photos/T6m2CepKiSZQQsKh8
https://goo.gl/photos/w3zLvbzxav6892TY6

This is the only time I’ve seen this phenomenon happen that I can recall. The overall thickness to the model seems to have increased after the line. Also, the line is more predominant towards the front of the vehicle and then sort of “blends” in towards the back. What’s going on here?


EXHIBIT E
(Cura_18.03/novelties/vanderbuilt_mansion)

IMAGES
https://goo.gl/photos/F9YbDTYvBNWjNbrY8
https://goo.gl/photos/zKCXoZcsXH9Rbxy67

This is obviously delamination of the layers. I think room temperature and possibly humidity levels maybe causing this. What is the recommended room temperature and humidity levels for printing ABS? Is there anything else that might be going on here that could be exasperating the problem?


FIRST PRINTS
(Cura_18.03/novelties/rocktopus)
Factory HIPS material provided by Aleph Objects

IMAGES
https://goo.gl/photos/xnEYU9Gv1D2esnyd6

After having all of these issues, I went back and closely looked at my first prints. The print that was printing by the factory looks really good. Initially I thought my first print was near perfect, but after looking at it more closely I can see there is some evidence of some overhang issues as pointed out in the above photo. What can I do to help mitigate this?

Any help you guys can provide would be greatly appreciated. I’m sure all of these issues are a result from my inexperience, so I’d like to learn what causes this issues and how to tweak my print process to neutralize them as much as possible.

I did a rough check of my e-Steps (don’t have an accurate way to measure mm) and it looks to be pretty spot on. I’m getting a set of digital calipers in the mail today, so I will go back and re-check it, along with measuring my filament width.

Thanks in advance for your help!

2

Hello, The filament that you are printing with has properties that are different than any other filament. ABS filament radiates thermally faster than other filaments. This causes the ambient temperature to be a significant factor in adhesion, layer adhesion and bridging issues. The one photo of the car window was due to no support structure included. The other photos are due to the ambient temperature, cooling the ABS too rapidly, so that it does not have time to adhere. Please turn off your 40mm fan so that your filament will adhere better. Also, most people that wish to print primarily with ABS, will build an enclosure around their printer, to maintain temperature and reduce these issues. Build a simple plexiglas enclosure with a hinged door to maintain temperature. We operate our printers that are printing ABS at an ambient temperature of 90 degrees. Try some of this and see what success you may have.

3

Thanks David,

I should have mentioned that the fan was off on all of these. Building an enclosure is definitely something that is on my agenda. However, after switching back to HIPS I’m still have a number of issues.

4

Here is a great link to common print problems and their cures. This is hosted on the Simplfy3D site but it applies to all printers and software. Studying these should help tremendously. https://www.simplify3d.com/support/print-quality-troubleshooting/

5

Well, I would start by saying; nothing like jumping into the deep end!

That being said you’re attempting to print some very complex models. The car is complex for two reasons (at least); 1. It has excessive bridging, 2. It does not have a flat surface.

On the mansion PRI t, you are delaminating. That’s either a temp. Issue or a Z offset issue.

OK, here’s my .02

For the car, primarily, it’s two things, how you position the car for print in the first place. You look to have really good first layer, and looking at the license plate, it looks like you’ve got things pretty well dialed. Looking at the hub of the wheel this is the same bisging issue as the window frames. There is just so far you can bridge depending on distance and thickness of bridge. As for the flat side of the car, the surface on the print bed that actually looks fine, give . That’s the first layer. Ifg you want to reorient the car, you’ll get different results. Remember, if you attempt printing wheels down you’ll want a raft, at least, to get good adhesion.

Now with the mansion, this is likely an ambient temp issue, given that the car, for all the issues your having, looks really good. This is likely due to cool air getting to the layer before it has time to adhere correctly.

You should search for “benchy”, the torture test for printer calibration. The car you are attempting to print has many similar. Properties.

6

Thanks CoParaTech,

Do you have any suggestions for mitigating the issues I’m seeing in the first example (the cat)? The lower part looks terrible, but the top 75% is near perfect.

7

To me, it looks like you’re getting a little too much heat from the bed building up at the bottom layers. I’d try reducing the bed temp a few degrees and see if that clears it up.

8

I fought that exact problem on some ABS prints recently, and tried various extruder/bed temps and fan settings without success.

I concluded the cause was a combination of the shape and characteristics of ABS. It seems to happen most on objects that “curve up and out” as they build up from the bed, like that cat model does. As the first few layers cool and shrink, they pull inward and (because of the somewhat conical shape) distort upward. That causes the previous layers to be too close – even touching – the print head as it tries to lay down a successive layer. Because the previous layer has moved upward, the plastic being extruded on the next layer has no place to go and “squishes outward” which causes the rough exterior.

In the end, I was unable to solve the problem using ABS. A very warm (like 80c+) heated enclosure would likely help, but I was not able to try that.

My final solution was to simply use a different material. HIPS eliminated about 95% of the problem, and PETG eliminated 99%.

9

Scott I think you are spot on in your assessment of that particular issue. However, I’m having similar issues with HIPS. Could you share your HIPS settings? I’d like to compare yours with mine.

Thanks!

10

I haven’t printed a sphere to check the underside in a while, but I had the same problems with a pumpkin a few years back.

My fix was to slow down the print speed (at least for the underside) and increase my infill overlap (which I think may be a bug in S3D, but worked to my advantage).

11

Delamination in ABS is mostly caused by too low of an extruder temperature. You can go pretty high with ABS. Even up to 260. The only downside is with some colors you can start to discolor or de-gloss them. An enclosure can help a little with delamination because an enclosure will lead to lower thermal stresses so the bond between layers can be lower and still not crack. But increasing the extruder temp will improve the bond between layers and allow for more thermal stresses before cracks occur, than it would with a cooler extruder.

When you are printing things like the cat, or other small objects out of ABS, you have to let the part cool down before putting down the next layer. With small objects and details in ABS, heat is no longer a friend but an enemy. Slower print speeds can help if you don’t have to go too slow. But if you slow down too much the part will overheat because of the slow extruder lol. I find with really small details you need to print multiple objects, it’s the easiest and best solution imo. Try printing 3 or 4 cats instead of changing print speeds, and be sure to turn off island optimization in your slicer.

Printing overhangs in ABS such as when a wall that curves or angles away from the support beneath, I find letting each layer cool (just like with small objects) helps a lot too. So again, the old standby for me is to print multiple parts, or if the part is big, slow the print speed way down. You can set up multiple processes in the slicer to do the areas like this slowly, and then speed back up for the rest of the model.

12

My thought exactly. :wink: Even the cat is a deceptively difficult shape.

Focusing on the fat cat. First, I’ve only bought one spool of IC3D ABS (in black) and I found that it was much more gooey than eSun’s ABS. I’m not saying for certain that is your problem, but when I look at the underside of the cat, I can imagine that the plastic in that area was still soft and moving around underneath the printhead, especially because that area has such a narrow diameter in those layers. To make matters worse, if your filament is sort of extra gooey, the nozzle will pick up a residue and become sticky and increase the amount those little nubs wobble around.

I’m printing a test of the cat right now in PETG, which is gooier than ABS. Watching the nozzle run over the feet and head low layers, I can see the nubs that are building up wobbling all over the place. I’m stopping it – it’s already looking terrible.

Getting the bottom right is a matter of letting it harden before you put on another layer, otherwise it’ll just wobble into ugliness. So for my second try, I’ve dropped down from 248 to 240 for my nozzle temperature, and from 85 to 75 for my bed temperature. Mind you this is with PETG. With ABS, maybe drop the bed to 100, or even 95, and the nozzle to 235.

In Cura, you can set a minimum layer time which may help. It is in expert settings, advanced tab, under “Cool” heading. I bumped that up to 60 seconds minimum per layer.

I’m using a lot of fan in my unheated garage with PETG because it seems to like the cold. The conventional wisdom with ABS is that you want to use as little cooling as possible because it doesn’t like cold. With too much cooling on ABS, you get layers splitting like in the house model you made. However, for a small piece like the cat, you might actually want to give cooling a try. It probably is small enough to avoid delamination, but getting those bottom layers really solid when they are just nubs so that they don’t wobble around is going to be key. It may take some fiddling to get the balance right between having the first few millimeters solidify, and the larger areas not delaminating.

Also, my first aborted bad version had 4 shell layers. My second more successful one only two layers. I think you want to have the nozzle on the edge of those nubs as little as possible. Anyway, it isn’t perfect (there is still some roughness on the underside) and more fiddling would make it better, but this is my result focusing on what is happening with the nubs (bottom of the spheres) – I cut off the round pedestal so it would be easier to see the bottom. Printed at 0.2 mm layer height:

IMG_0628.JPG
IMG_0628.JPG3456×2304 2.22 MB

IMG_0627.JPG
IMG_0627.JPG3456×2304 2.26 MB

IMG_0626.JPG
IMG_0626.JPG3456×2304 2.26 MB

13

I see the exact same issue with PLA, but not as bad with Alloy 910. Has the Lulzbot team changed or created any specific Cura profiles to print sphere type objects? Being an intermediate in this technology, I’m finding all sorts of shrinkage issues I did not expect to see.