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The Ultimaker 3 should only be used up to 280°C, we don't support higher temperatures. Going above 280°C will degrade your silicone flaps really quickly, reducing the reliability of your printhead. The emissions of the printing process also tend to quickly rise when increasing the nozzle temperature, so watch out for VOCs and Ultrafine particles! Especially with PVDF, which should melt at lower temperatures. Printing outside of the printcore specifications could also reduce the lifetime of your printcore. The errors showing up are probably because you are working at the edge of what the heater can handle.

The STL file and the gcode are not for the same model, but I do see that both models have high resolutions in the rounded corners. The curaprofile file is not really clear, as you have made your own materials (material = empty_material). In dual extrusion we spend a lot of time making the heatup/cooldown of the idle nozzle happen while the other nozzle was printing. A small change (in standby temperature, heatup speed, cooldown speed, etc) could disrupt this. That would cause the printer to wait between layers, untill the nozzle is heated. This waiting time is (of course) not included in the Cura estimation, as it assumes that the values are tuned so it doesn't have to wait. Back to the rounded corners: using the Cura 3.3 beta and the latest firmware, the estimation may be a lot better (less slowdown on high resolution parts).

Sorry for the very late answer, I've been a bit busy lately. First of all: please watch out with placing non-food objects in your microwave. Your microwave works by heating water, but if there is not enough water in the microwave, it can overheat. It is often recommended to place a glass of water in the corner of the microwave to absorb energy. I know this because I've spend some time microwaving stuff for my graduation research (making Graphene) and just for fun . I believe PLA can become brittle because of multiple reasons. - Polymers have relaxed into a certain state, and alignment (crystallinity) makes it stay in that state. Changing the shape of the filament will break these alignments, reducing the stability. It will take a lot of time for PLA to relax again, as this is a very slow crystallizing material. A higher temperature leads to faster relaxation, which is why annealing (hot water, oven, microwave, etc) changes how the material behaves. - Degradation leads to brittleness. I don't think a measurable amount of hydrolysis will happen at normal storing conditions, but UV damage can make a polymer brittle. Degradation is irreversible damage. This damage is mostly happening on the surface of the material, exactly where you will have the most stresses. - Changing of composition will also lead to changes in the behaviour. But for PLA, I believe the only change will be that some water is absorbed. Absorbing water could make the material slightly softer at first, but it could also be a 'seed' for crystallization, increasing brittleness...

I think this could easily be fixed by changing the temperatures in the slicing settings: make the standby temperature and the initial and final printing temperature the same as the printing temperature. Do this for each extruder, otherwise it will still fail (I often forget this...).

Heey Cura team! ~ How many people outside of Ultimaker are working on Cura? And how do you decide which contributions from outside Ultimaker are used and which aren't?

I've been playing with this feature already! It was a bit unstable in the beta, kept crashing my Cura. But I like the results now, especially for parts with many holes in the top or bottom surface.

I really need Cura to know if I'm going to print single or dual extrusion on the UM3, Interesting, I would have thought bridge detection and speed/cooling settings for bridging. That would be great, but printing a bottom layer/bridge on top of PVA should be done differently than printing one in the air/on normal supports. We could maybe do this with resolve functions, but it would be great to have a 'smarter' system.

Thanks for the opportunity to do this AMA, I enjoyed it! This will be the last question I answer in this thread, I will be leaving for holidays (but you'll find me back on the forum in around two weeks). I would be interested in an AMA with a member of the Cura Software team, for questions like : - How many people outside of Ultimaker are working on Cura? - How do you decide which contributions from outside Ultimaker are used and which aren't? - Are there any new infill patterns that you would like to create/add? - Are you already getting tired of me breaking your software?

PP, PE, PVC, PS and PET are by far the most used plastics at the moment. So the big focus for recycling plastics is mainly on these materials (although PVC is messy). These are not typical 3D printing materials... And on top of that, 3D printing materials often have additives like pigments, which make recycling even harder. You could recycle plastics yourself by using a filament extruder, but these are expensive. In the Netherlands we have a bag for recyclables that get's picked up or can be dropped off for recycling. I would put PETG and PP prints in the bag, but I know that it's very expensive to recycle plastics and most likely they will be burned for electricity anyway. I think the 3D printing material market has to grow a lot before recycling materials becomes interesting, especially if you compare it to the use of plastics for packaging.

PC can be hard to print well, especially with big overhangs and organic shapes. I like to print mechanical/engineering parts at 0.15mm layer height, because you get details and less warping and cracking. Enclosing the printer and preheating the bed to 110C helps as well. Bridging is hard with PC... Maybe you can increase top/bottom speed a bit and use support interface? Depends a bit on the model shape what would work best (which is the annoying part of making profiles...).

It seems to bond best to Nylon and TPU’s, but with Cura 2.6 bonding to PLA is much more reliable for me as well. CPE is possible as well now we have the Cura 2.6 new features. For me it works best if I first clean the nozzles (outside part), and do a good bed levelling and XY calibration before I do a long/challenging print. What about ASA, my currently favorite material? I haven't looked into ASA yet, but I do know that the lack of of Butadiene makes it more UV stable. From what I understood, it's like ABS but more rigid. Why is it your favorite material? ABS often sticks to PVA while printing the model, and PVA can stick to ABS. But after dissolving the parts often started warping for me. And if the part had a really bad tendency to warp, it warped off the PVA during the print. I think ASA could stick better to PVA due to the chemistry, but I don't know how much it warps.

We want to do this, but we want to implement this in a nice way. Like a toggle in the ‘Recommended’ mode of Cura that just turns the fan lower, the printing temperature up and evens out the speeds. For dimensional accuracy we would also try to compensate using the horizontal expansion, but this is different per material. I’m worried that it would be a lot more work to also do this for dual extrusion... But that would just require to the user to use UM tag materials (UM could tun basic tests). The problem I see, is that low jerk/accel tricks to make all beautiful can/and do, make external errors on curves to compensate the ringing and heavier head of the um3 system. Our profiles are made with our materials, but some of the behavior is specific to the polymer type used. The profiles can be used as a starting point if you want to tune your own materials. The jerk could be increased, as ringing isn't as much as an issue, while you want your curves and corners to be printed precisely.

https://www.thingiverse.com/thing:356037 I printed this over half a year before the UM3 was released, finally showing off the capabilities of PVA. The model has really big tolerances (probably because it was designed for another printer), but it still works and has great details in the middle of the ‘ball’. The first and second time I’ve printed it, the print got stolen (I did see one in a picture from our US office), so these two will stay behind a lock:

I've played with PVA on the UM2 with special nozzles, but the feeder has a hard time feeding the material. Olsson block nozzles can easily print PVA, so I recommend doing it on a UM2+ (or at least change out the nozzle). Students at TU Delft already played with this concept:

We want to do this, but we want to implement this in a nice way. Like a toggle in the ‘Recommended’ mode of Cura that just turns the fan lower, the printing temperature up and evens out the speeds. For dimensional accuracy we would also try to compensate using the horizontal expansion, but this is different per material. I’m worried that it would be a lot more work to also do this for dual extrusion...

Nylon if I need good supports/complicated models, and PP if it's an easier model. I've printed a big PP Ultimaker robot which we haven't been able to break yet (not even with a hammer). I've also dried Nylon parts at over 90C without any issues, and I love the look of 100% infill Nylon parts printed at lower layer heights (0.1mm). They look injection molded.

Personally I've used Slic3r before as I had issues printing PVA with Cura 15. It had some nice support features that we missed at that time. But it crashed at lot at the time, I couldn't slice complicated models with dual extrusion supports. With S3D I'm not very experienced yet, when I tried it it didn't cool down and heat up the unused nozzle while the other was printing. So it was too slow for me at the time. Lately I haven't had much time to look at other slicers as we are implementing a lot of new features each Cura sprint, that we also need to find good setting values for.

I really need Cura to know if I'm going to print single or dual extrusion on the UM3, so I can have specific settings for single extrusion and for dual extrusion. Setting up a single extrusion 0.8mm printcore PLA print at 'Sprint' speed (0.4mm layer height) while you have an 0.4mm printcore with ABS loaded in the other slot is leading to some issues. (ABS build plate temperature is used for example)

Both. During the profiling we do it by feel and simple tensile test at first. We also have had a lot of our tensile bars tested with ISO standards, but there are no real ISO standards on how to print it (as no two printers are the same, and settings have a lot of effect on the strenght). We try to use data from 3D printed samples as much as possible in our technical data sheets.

Good one, and it links to another question I saw earlier; Are the print profiles in Cura aimed to make prints that look nice, strong prints, or a middle ground of everything? What do you have in goal when making a profile? The profiles are now made to be somewhat in the middle ground. PLA profiles have one less wall than ABS profiles so it’s slightly material dependent. I went for strong and nice at the same time, now we are trying (and succeeding!) to speed things up without losing these qualities.

It could indeed be a blog post, but I'll try to give a shorter answer here: First we start by finding the processing temperature by printing and measuring (caliper and scale) the extruded part. Then we try and find fan settings at which we have strong layer bonding, and a bed temperature at which we don't have warping. With these three settings (printing temperature, regular fan speed and bed temperature) done, we can start looking at speeds. You want to print as fast as possible, but also want the overhangs to be printed nicely. So the outer wall must be printed slowly, the infill faster. We use a lot of models to tune these settings, and we try to even out the flow with the inner wall lines. And then there is the tuning for the z-seam, for top details, for top layer to walls connection, for the bridging, etc etc... All the profiles for new materials are tested in the company by our testing team, and often tested outside the company by beta testers. Their feedback decides if a profile/material can be launched.

We've played with PVAs, BVOHs (and blends of the two), HIPS and some more materials. We went for PVA because of the dissolvation speed and because it fully dissolves in water. Other materials, disintegrate into a milky mess (BVOH), need nasty chemicals (HIPS) or are unreliable to print. The nasty chemicals for HIPS also seemed to have effect on ABS, which we didn't like. We are continuously looking into more support materials, as we strive to be able to have support solution for every build material.

I’m really interested in the metal-polymer materials, from which the polymer can be burned out to form a pure metal object. Unfortunately sintering the part is harder and more expensive to do than the printing… Using an Ultimaker to print metal jewelry would be awesome! Maybe it could be possible to use this technique for ceramics/glasses for even more possibilities.

I often use the ‘OK Hand’ model and the 3D Benchy to test my settings, but I start out with simple shapes like cubes, balls, overhangs, etc. I like the OK Hand the most since it can also be used to test layer bonding (by cruelly breaking the fingers). I will use the Benchy for dual because it's a terrible model to print.

It’s already possible to print with conductive materials, but the possibilities are very limited. The resistance of Carbon-filled (Graphene, Carbon Nanotubes, Carbon Black) materials is still pretty high. It’s just enough to turn on some LEDs with a big battery. There are some issues on the process/printer side as well: Carbon-filled materials eat nozzles for breakfast, and Carbon nanotubes are about as hard as diamond… I think printing conductive materials for simple leads is already possible, but functionally prototyping devices will take some years of material, software and printer development.