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Using Ngen 3 to produce transparent features

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i have had soime problems getting good transparency from my printed parts on the ultimaker 3.i have been using the ultimaker 3 with colorfabb ngen in an open office enviroment

The intial settings where, temp-235 which i decreased in stepsdown to 220. this improved result but stayed more white than transparent. plate temp at 70 intially but heated to 80 by the final attempt.

flow rate-130%, fan 50% tried with and without.layer height intially 0.08mm but in final attempt 0.16mm. printed at 40mm a second. despite playing with these settings i cannot get a satisfactory transparency.

does anyone have any different suggested settings to print at?

. i also have the HT from colorfabb which i will try tomorrow.

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@iRoberti had good luck with some material. Not ngen though. Not sure which material but he got amazing transparency. Maybe try to message him? He's not been active on the forum for about a year but give ti a shot. I talk to him every day (but not through the forum). So if he doesn't reply after a day let me know. I'll send him a link to this topic now...

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HT is what I used to get my results. You need heat, slow speed, thin layers and preferably a bigger nozzle (0.8 nozzles just came out for the UM3 so that's sorted).

One issue with the thin layers and high temp is that you get buildup of material on the nozzle. It then burns and starts flaking off into the print leaving brown marks all over. I was using an UM2+ at the time and designed a little arm that holds a wire brush. I then created a plugin that makes the head move over to the brush and clean it off every few layers.

And then after all that you need to polish the crap out of the print. Wet sandpaper followed by a polishing wheel with polishing paste is what I used.

I posted one of my prints at the link below. I made a few more prints after that where I improved the result slightly but I never bothered taking any pics of that.

https://ultimaker.com/en/community/prints/508-ht-clear-experiment

I also gave nGen a try but didn't have much luck with it. It got cloudy quite quickly as soon as the print got up to a height where the heat from the bed wasn't contributing as much.

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I just bought myself a big spool of Colorfabb Ngen Clear. OMG, do I regret this. I've tried all kinds of combinations. Nozzle, infill, temperature. I get something translucent but not transparent. But on the positive side. I've now got myself a big useless spool I can experiment with because the quality of the prints is still very good.

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I have done several tests with transparent PET, ICE brand. I found that the results are better when printing slow: 25mm/s, so that the the flow is very regular, and the material has time to flow into all corners. Printing at the cooler end of the range also helped. I don't know why, since I expected the opposite. Printing at medium temps caused more opaqueness, and printing hotter was more transparent again, but it caused too much accumulation on the nozzle indeed.

 

I also noticed that transparent light grey filament looks more transparent than water clear, colorless filament. The water clear becomes bright white due to the reflections and refractions. But the grey filament seems to absorb some of that light, and thus reflects less. Also yellow looks more transparent than colorless, probably for the same reason.

 

I also read that in PET the crystal structure may have an influence on transparency. And that crystal structure could change with age, temperature, moisture and processing methods. If NGEN is something polyester-like, I can imagine that this might also play a role. Of course, too much moisture will allways cause little steam bubbles inside the extruded sausages, or craters popping open on the surface, and it will make it less transparent. Under my microscope I can clearly see those bubbles in the sausages.

 

But anyway, the transparency lasts only a few layers, and then it becomes translucent indeed, due to the light reflections caused by the trapped air in-between the sausages. I got nowhere close to the tests of |Robert|.

 

So these sorts of "transparent" filament are very usefull for making hollowed-out text inside the model, like company logos or copyright info: if close to the bottom, it shines through good enough. But it is useless for lenses.

 

Have a look at these examples. If I remember well, the "TOP SIDE" text was 1mm high, sitting 0.5mm below the surface. Both photos are yellow and red ICE PET. It won't get much better than that with PET.

 

topside_keys.thumb.jpg.81284fbf63eeba1aea0ee0804af744d7.jpg

 

top_side2_cut.thumb.jpg.e86c8dae490a8719789e5aa15ec5a6c7.jpg

 

horseshoeclip.jpg.f0b28c4ee645faf0935adc8b67b35887.jpg

 

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