Hello!
I received an order on 3DHubs for a client who is requesting various, let’s call them, anatomically correct larger scale action figure parts.
I’m printing with ABS, and normally don’t have any problems like this, I’ve been working with ABS long enough to anticipate problems and have some of my own work-around methods to ensure a good print. The models are high res, and were well designed for 3D printing. The client insists on the greatest possible detail, which means each part takes between 4 - 8 hours to print. I’m mostly satisfied with the final prints, but then I noticed this - cracking between the layers. It was not obvious while printing, I noticed this part, which I printed yesterday, had two clear cracks between layers.
I don’t normally have a need to print more organically shaped parts, and for my own needs prefer to print in PLA to avoid these things.
From your experience, what is usually the culprit for cracks between layers with ABS?
Printing at:
Extruder at 240C, bed at 110C,
.35mm nozzle,
50mm/second speed,
20% infill,
Layer height at .16mm,
Any ideas?
This happens when the ABSD cools too rapidly. Make sure the fan is off, and it is best to print using a completely enclosed 3D printer. You can avoid problems like this but still attain the strength characteristics of ABS by printing with PETG+ filament.
I would just notify the customer of the issue. From my 3D hubs orders I’ve noticed that being upfront is always helpful. Try to convince them to allow you to switch to PLA and just explain the issue with the abs. It might be well designed for 3D printing but maybe not for printing in abs.
If your customer is willing get some Squadron putty and smear it into the crack. Then after an hour, wet the whole thing and wipe off the excess. The putty will cure hard and seal the crack. Do this for smaller cracks only. For bigger cracks I use my 3d Print pen to fill cracks, then sand clean, then coat in XTC3D and then paint.
This is great information, thanks for feedback! I showed the client the pictures I took of the print and I think he is going to do an acetone vapor post processing, and that should make it less visible if not fill it out completely. Trying to sell him on PLA but he is insisting on ABS.
If he wants to vapor smooth them in the end (regardless of the crack) then the ABS is understandable. You have the printer enclosed correct?
Don’t most folks desiring anatomically correct “action figures” go for silicone? Anyway, it’d be easier to fix a printed mold, then cast the perfect part.
If you simply print hotter, the cracking probably won’t occur. ABS is pretty tolerant of high temps, try cranking up 10-20C and see how it goes. But it’s fundamentally happening because your build chamber is too cold and/or you have too much airflow on the print.
If you were planning on solvent smoothing later you could fill tbe crack with an abs paste or fix with a doodler type pen.
But yeah, really need a closed chamber. I’ve been thinking of a flexible bag system where only the hot side of the hot end is inside. Still gotta test, but the plastic baking bags for cooking turkeys will stand the heat. Same for vacuum bagging films used in composites manufacturing.
Ditto the enclosed chamber, but adding strong recommendation of heating build volume. I usually have about 50°C temps and even pretty large parts come out great, no warp and no brittleness.
Am I the only person that sees “anatomically correct larger scale action figure parts” and wants to see what the whole print looks like 
Nope at least 2 of us are that sick 
I have printed some pretty large and complex organic prints that have nothing to do with any kind of anatomy known to science or fiction, and have experienced this sort of cracking once or twice.
I don’t use an enclosed chamber, and it makes little difference in my experience. As it is, the cracking only occurred much later, around two or three days later.
The key is to print at a sufficiently high temperature that interlayer adhesion is good and to have thicker walls. For example, this vase was printed with a 0.8mm nozzle, 0.4mm layer height, bed at 110C and nozzle at 260C, speed around 45mm/sec. The walls are 2.4mm thick, i.e. 3 nozzle widths.
https://d2py9w124w2itd.cloudfront.net/photo/image/2500x0/57269d8838cb3/family%20vase.jpg
@Alex_Krause I actually cropped the attached photo about a minute after I posted it, thought the whole piece would give more context to the organic shape of the model. Then I thought I didn’t want to get in trouble for posting vulgar things, so I kept it clean fun for the whole family.
I don’t have an enclosure on my printer - I’m using a Lulzbot Taz 5 - but the environmental conditions where my printer is, are pretty stable, no cold drafts or anything other than maybe a little humid, which I know ABS has a reputation for being very responsive to environmental factors.
I am reprinting a couple of parts that had the deepest cracks in them. I made the wall size a bit thicker, increased the density of supports and included a brim so supports stay attached to the bed. I also changed the supports from Lines to Grid. I began printing with the bed at 110C and about five or so layers in, I decreased it to 100C, printing temp at 240C throughout, slowed the print to 45mm/second with the infill and support at 60mm/second, and I changed the cooling fan settings down to max 20% I need the cooling fan for the supports more than anything else, those narrow little columns have a tendency to get sticky on the nozzle, and the extruder pulls it right off the bed and drags chaos all over the place.
Of course you realize now I am trying to extrapolate what the rest of this thing is. And it’s all @Alex_Krause 's fault …LOL
Not for if anyone else mentioned this but I would definitely create some abs slurry of that filament and just fill the area. It will look perfect.
Agreed, it’s the simplest solution. But make it fairly thin so it runs into the cracks easily.
I think the ABS Slurry is the best option since it can be sanded down and smoothed out to match the rest of the model without degrading it. And I won’t have to keep reprinting it and hoping that this time it’ll come out better - if this was a pet project I would but since this is for a client, turn around time matters.
