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djyeo

Is this too small for UM2 to handle

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I have been trying to print this mini Eiffel Tower, as you can see, the first few layers printed fine up until 2/4 of the way. I printed at 0.1 layer height and 200 degrees temp (first base layer was set at 220). Speed was 40mm. Is this too small for the 0.4 nozzle to handle? Is there anything I can adjust to make this possible?

During the print, it looks to me like the nozzle extruded too much filament starting halfway up.

7d02ad382817275.jpg

 

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Ok i see :) it's very small indeed.

What happened here i think is not overextrusion but probably because the top part is small, the nozzle tends to melt the previous layers causing it to show blobs.

What you can do is either print two at once to make the previous layer cool down more. Or add small tower of the same height next to it and print both at once (make sure you position the tower at a place where the fans blow on the object for better result).

You also need to set the print temp to the lowest possible (around 190°c depending on the filament).

 

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Thanks so much for the reply Didier, is it possible to set the nozzle to pause printing for a few seconds after every layer, starting from the middle up?

 

That is possible, but usually not desirable. Once the nozzle is heated up, you can't just "stop" extruding for a few seconds. Instead, there will be some material oozing from the nozzle. When the print resumes, that ooze will make it's way onto your printed object.

Another side effect from oozing is, that there will be some material "missing" in the nozzle -> underextrusion upon resuming. (*)

So, as Didier just mentioned - printing multiple objects instead is better because that way the printer doesn't "pause and resume" but just divides time between multiple printed objects.

* With the continuing development of dual-head extruders, these problems might be fixed (more like worked around) soon. But any fix will just mean that the printer has to "do something suitable" with the oozing material. Meaning printing a second object next to the "actual printed object". So, again -> just print two (or more) at once to get the very same effect.

//

By the way. What's the layer height? (Ignore that. just read it...)

You can go as low as 0.02mm for layer height (I've done 0.025 mm prints myself. Sander from the UM team did a 0.02mm print on a UM2 iirc).

If you print slowly (30mm/s would be my choice), you can probably lower your printing temperature considerably. For PLA, you could do with temperatures as low as 170 or 180°C (depends a lot on the filament you use). You'll probably have to keep the first layer hot, around 200°C should be enough though. Lowering the first layer height to 0.2mm will help with adhesion.

Your tiny object will turn out best at the lowest possible temperature.

 

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I cannot tell how small it is, no picture access, but it looks SMALL. Yes you need to go to at least 30mm/s I think I would be inclined to use 20mm/s/ 100% fans asap. Minimum layer time 10 sec. Not sure if printing 2 towers will be sufficient, you might need to go to more - all depends on the size. I agree with Peggy B on cool head lift it can be really useful and the threads easily removed with a modelling knife, certainly worth a try if you are struggling. As Didier and Jonny have said, get that extruder temp down loow

 

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your first layer height is set in the advanced tab -> initial layer thickness.

You're welcome to use 0.025 layer height, I think the printer is technical able to do that, but in my experience anything lower than 0.06 is hardly visible (but it will take about 3 times longer..) and correct me if I am wrong :-P

 

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And using thinner layers for small prints can actually produce worse quality sometimes. It's a bit counter intuitive but that's the way it is.

This. I've literally arrived at this after multiple prints in layers below 100 microns on one recent print (the "linkage" on the Oblivion Defender Drone) to only find out that 100+ microns worked the best.

I chock it up to the "art of printing" lol.

 

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Thanks all for the suggestions and tips, so I scaled up the model slightly in cura to 1.1 and printed two at the same time and got this result. I know the top end part could have been better if I could lower the speed some more. Printed this at 190 degrees with speed at around 25mm and 0.06 layer height. Printed without support. I have to set Z lift at 0.2 otherwise the nozzle would hit some of the printed parts.

IMG_1053.JPG

 

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It looks very good already :)

I guess it would take me at least 3 tries to get on par with this print. Plus I'd have to improve my cooling setup first (modded UMO is just not the same as an UM2 ;)).

I also noticed that thinner layers aren't necessarily good for printing quality. Especially any kind of bridging gets better the thicker the layers are. For my technical prints I've recently started to use 0.2mm layer height exclusively. Bridging is almost perfect, it prints a lot faster (even at 30mm/s) because there are less layers to print in total.

But your tiny eiffel tower will not look good at 0.2mm layer height - obviously you lose a lot of detail.

When printing thin layers, it's essential that you print with the lowest possible nozzle temperature and use 100% cooling fan. Also, printing faster gets better results than printing slow, because you don't want the nozzle to remain in one spot for too long.

3D printing is more than just pressing a button and getting a nice thing out of the printer. You have to observe, understand what's happening, and think about how to improve it for the next time...

 

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I agree, it definitely is easier to control the output of filament with 0.2mm. As a "newbie" in 3D print world, it has been very interesting for me, every shapes and models require a unique setting to print and it sure takes experience to get the perfect print.

 

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