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wallan

Need some advice on ABS printing

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Need some advice on ABS printing.

I like the PLA it prints really god but...

It's so hard to get a perfect smooth surface unless using a filler and sanding.

I mostly print figures and as long they are nude it's not such a big problem to sand it.

But on a figure with cloths and accessories i would be a nightmare.

ABS on the other hand can smoothed to quite a nice surface by just brushing it with Aceton (don't know if it's called the same in English).

But, with ABS I have so much warping problem.

I have asked for help before and collected some advice i found and thing works far better but there is still a couple of problems that I would like suggestions on how to solve.

I now brush with ABS slurry before print. That makes a god bond.

I currently print direct on the slurry using neither raft or brim but just the skirt to prime the nozzle.

After first layer I turn of the heated bed and Fans are off all time for more even cooling.

Temperature first layer is 260 and thereafter 255.

Layer 0.1

Shell 0.8

I have two problems.

First image shows that there are problems in some places where i get holes.

Maybe not that surprising, maybe more of a surprise that it did work in PLA.

What would be the best solution here.

Any setting that can solve it or is an inner support needed or maybe i should add infill. But I don't want to risk more warping either.

 

IMG 8886

 

Second image shows, but not in a very god way the other problem.

It's when a part is like a turned over cone. A small base and wider on the top.

Consider that the cone aren't round but more of an oval.

When printing, the pointier curves tens to warp upwards and sooner or later the nozzle will hit it with enough force to make it break of.

In the image it did not brake of but rather move a little so it's not that obvious.

Any suggestions.

More support could of course be added in the model itself of course but that wont prevent the real problem that is the warping that makes the nozzle bump into it so it might come lose anyway.

IMG 8887

 

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You do need some infill to support the surface while printing and brace the piece against warping, even if it is not needed for strength. Try 15%, and experiment.

You should definitely experiment with lower extruder temps - 260C is at the limit of the ptfe liner in the extruder, and most ABS prints fine in the 230-235C range. It varies quite a bit by manufacturer: with protoparadigm ABS, I print at 227C for best quality on my parts, and 225C for Ultimachine, although others might prefer higher for a smoother finish.

However, you can smooth the surface with acetone - search for "ABS smoothing acetone vapor" for better techniques than a paintbrush.

 

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I dont think its possible to print with ABS in any consistent manner. I've try many ways but warping is stronger than me.

I use a heated bed, tried with heaters blowing on it, super-glued the base down but it will then warp and split between layers higher up in the print. You might get lucky with a certain shaped print, but most of the time it will warp somewhere.

I only print large objects which are more prone to warping.

 

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I've only had warping a couple of times with ABS, with prints up to 10" tall. The key seemed to be ambient temperature: when my printer was running for a while it would warm the room up to 80-82F, and that allowed the ABS to cool evenly enough that the layers did not separate or warp.

Like a souffle, don't open the oven door while cooking...

 

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To sum it up.

Try lower temperature.

If that dont fix the i will need some infill or support.

Maybe try covering the front on the printer to get a more even temperature inside the printer.

I'll try that this evening.

I vill really like to get ABS to work.

That face, apart from the holes is so smooth that I hardly even need to smooth it.

And that vapor method. I have read about it before and it did sound a bit unhealthy and dangerous to me.

Also a bit problematic maybe because of the size of things.

Getting some brusch strokes in there is not that much of a problem for me as i will paint it with brush and oils in the

end. I will however read up on it and not discard it based on the little I have read about it so far.

 

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A bit better but not quite there.

Tried with 20% infill and temperature lowered to 245 and i did cover the opening in the printer for a more even and slow cool down..

The infill did not line up with the critical points so it did not help much in solving the problems with the holes.

IMG 8888

 

In the second attempt i decreased infill to 10% as it not helped much anyway, lowered the temperature to 235 and increased shell to 1,2.

 

Result is quite similar to the previous.

 

 

IMG 8889

 

I think that booth prints would had come out nice if there was support structures on the inside as they would had added support at correct places.

I did however not manage to get Cura 14.03 Test2 to create any.

 

Adding support in the 3D Modeller would be very hard I think as it most follow contours and match up exactly with the cuts as well.

Any suggestions?

One thing I can say for sure is that the slurry makes a really god bond to the glass.

No risk of the parts warping because they comes lose from the bed.

 

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I just got my UM2 and have no experience with ABS on it, but I also have a makerbot (first gen) and for the past 2 years, i have printed with ABS exclusively. ABS does not send well, and using acetone to make it smoother will remove the detail as well, basically you are "melting" the plastic in a controlled manner. The only way, that I have seen, to get those fine details you are looking for, would be to print with a smaller nozzle, such as a .02mm. Of course printing time would be somewhat longer....

 

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It would be interesting to try a 0.2mm nozzle some day.

And the effect on details that acetone has is also a reason for applying it with a brush for more control of the effect.

But on the other hand all surface treatments will have that effect. Filling and sanding / tumbling PLA will do the same.

Another problem i see with acetone is that the surface might get so smooth that I probably have to spray it with matte color in order to get my oil paint to stick to it and not just slide around. Airbrushing would of course work fine but I find it more fun to use oils and I can paint anywhere.

However, as my figure models are pretty large 25-45cm, I'm quite happy with the level of detail that I get with current nozzle.

My main problem with the ABS at the moment is the holes i get.

But that is mainly a support issue.

And as there seems to be someone working on that part there will probably be better support structures in the future.

Are there anyone that can tell me what the requirements are for getting Cura to create support to the inside of the head, if possible?

 

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Increased fill to 30, not to make it stronger but more as an sustitute for an internal support.

As I Cant get cura to create any.

Increased shell to 1,2 as well.

I still get a hole on the chin as the infill not hits exactly the right spot but another nice thing with abs is that the slurry works really nice as a filler as well.

I think this will do.

Gonna try a full figure next in order to evaluate abs for the full process.

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Holes appear on "top" surfaces due to insufficiently thickness of the top layers in respect to the fill density used. Sparse infill requires thicker top, while using a higher infill may work with thinner top. Since you do not normally require a strong figurine, increasing fill density is not necessary, but this would in turn require to increase the top thickness.

I'm not normally using Cura, but I observed that the thickness of the top is coupled with that of the bottom, which is not very useful either. It means that if you increase thickness of the top, the same will be on the bottom, but this will unnecessarily prolong the print time and waste material. In Slic3r (well, I know not so many people like it, but I got used to) top and bottom thickness is decoupled (you can specify separately the number of layers at the top and at the bottom).

Now, the actual values of the two fill parameters in Cura depend on some other factors as well, such as layer height, temperature, speed and cooling. Shell should not count too much since the slicer is adding some additional 100% infill when the curvature of the model requires. But, it will still count for the top thickness that was set.

I'm printing figurines in ABS with 0.2 mm layer height, 40 mm/s at 230C, and I'm using 30% infill and 4 top layers (i.e. 0.8 mm). When using only 3 layers and 30% infill, or 4 top layers and 20% infill, I got sometimes holes.

Printing at 0.1 mm layer height would probably require more top layers, though the total height might be lower (e.g. 0.5-0.6 mm). This will add to the total print time, but there will be no issues with holes.

More aggressive local cooling may help as it will do with the second issue mentioned in the initial post: overhangs. However, cooling might impact bed adhesion, particularly if the print time is long and/or the footprint is large. If cooling do not suffice, you need support (not so bad, since you're going to finish the object anyway). If cooling result in margins lifting from the bed, try a 2-3 mm brim around the model.

 

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Holes appear on "top" surfaces due to insufficiently thickness of the top layers in respect to the fill density used. Sparse infill requires thicker top, while using a higher infill may work with thinner top. Since you do not normally require a strong figurine, increasing fill density is not necessary, but this would in turn require to increase the top thickness.

 

I'm not normally using Cura, but I observed that the thickness of the top is coupled with that of the bottom, which is not very useful either. It means that if you increase thickness of the top, the same will be on the bottom, but this will unnecessarily prolong the print time and waste material. In Slic3r (well, I know not so many people like it, but I got used to) top and bottom thickness is decoupled (you can specify separately the number of layers at the top and at the bottom).

 

Now, the actual values of the two fill parameters in Cura depend on some other factors as well, such as layer height, temperature, speed and cooling. Shell should not count too much since the slicer is adding some additional 100% infill when the curvature of the model requires. But, it will still count for the top thickness that was set.

 

I'm printing figurines in ABS with 0.2 mm layer height, 40 mm/s at 230C, and I'm using 30% infill and 4 top layers (i.e. 0.8 mm). When using only 3 layers and 30% infill, or 4 top layers and 20% infill, I got sometimes holes.

 

Printing at 0.1 mm layer height would probably require more top layers, though the total height might be lower (e.g. 0.5-0.6 mm). This will add to the total print time, but there will be no issues with holes.

 

More aggressive local cooling may help as it will do with the second issue mentioned in the initial post: overhangs. However, cooling might impact bed adhesion, particularly if the print time is long and/or the footprint is large. If cooling do not suffice, you need support (not so bad, since you're going to finish the object anyway). If cooling result in margins lifting from the bed, try a 2-3 mm brim around the model.

 

Ah, so top thickness is used even if it is a continous shape. I thought it considered it as the shell. That explains why i get holes as i have tuned of topand bottom.

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