2 color printing

[mamastoast 0]

The company I work at has an ultimaker 3s and we are currently attempting to print what are essentially balls in one color with a detailed pattern of another color added to the surface of the ball.

 

I've split the ball in 2 halves and the prints are mostly successful however each island of the small details printed in the second color has bits of plastic sticking out and is generally uneven and weird.

 

Is there a setting in ultimaker to avoid this type of issue ?

 

Sadly I don't currently have any picture to share since all our prints have been sanded down .

Edited June 24, 2021 by mamastoast

[Enigma_M4 120]

Hi,

if you're talking about plastic of the "wrong" kind, that's where it shouldn't be, you could try using a prime tower (in Cura: settings -> dual extrusion -> enable prime tower). This helps priming the nozzles and wiping oozed material before it can contamine the print.

Regards

 

[mamastoast 0]

Thank you for the reply.

Cura automatically enabled the prime tower when I assigned the details to be printed in a second color, so that is already taken care of.

To try and better explain it, it's sort of like the nozzle is dragging the remaining second color material away from or into the rest of the ball when it's done with an island of the second material during printing.. This results in the colors kinda blending a few places and the ball being pretty spikey and have loose bits of material 2 sticking out everywhere.

I've started a new print so hopefully I'll have an image to explain it better tomorrow.

Edited June 24, 2021 by mamastoast

[Carbon 28]

Have you tried a different orientation? (Spinning the ball around....)

[mamastoast 0]

Pictures to clarify the issue

[Enigma_M4 120]

Ok,

the pictures really clarify your issue, which consists of stringing and some "insect antennas" (two terms worth searching the forum 😉).

I assume the material you're printing is CPE or PETG?

There's good and  bad news:

good as these artifacts can be reduced or even avoided by fine-tuning the print settings,

bad as this is far beyond my knowledge and I can't really help furthermore.

@Smithy, do you know a solution, or someone who can help?

[Smithy 1,145]

Not a solution, but some ideas I would try:

• Turn off combing
• Print cooler with the yellow one, to avoid too much oozing
• Play with the retract settings, increase length a little bit and maybe also speed
• Try if it is better when you increase the distance between the two halfs

[mamastoast 0]

I've tried playing around with retraction settings and at lower temps and lower speeds... so far no improvement. I'll try disabling combing for my next attempt... Right now I'm printing a set with even more extremely retractions settings.

With regards to materials I've actually tried quite a few different ones with no visible difference

Edited June 30, 2021 by mamastoast

[CalebPetersenPhD 0]

What are your retraction speeds and distances for each extruder?  You probably noticed this, but they will be different for each extruder (make sure to go to both extruders' respective tabs and set them appropriately in Cura).  Sometimes retracting too much and too fast has paradoxical effects.

[geert_2 558]

In my experience the "insect antennas" are caused by the nozzle leaking while traveling through air. Upon reaching the next wall, that drop is deposited on the side of the wall. The next layer, the drop is deposited on the already existing drop, and so on, creating the "insect antenna" effect. Watch closely, then you see it happening. In PLA this is rare, but in more rubbery materials when molten, like PET, it is common.

 

You can easily worsen the effect by switching off retraction, or by printing faster (=more pressure in the nozzle, thus more leaking). Reducing it can be done by printing slower, in thinner layers, cooler, and with all speeds the same (walls and infill). But I can not totally avoid it, unfortunately.

 

The strings often come from material accumulating on the outside of the nozzle, and then slowly sagging onto the print. Sometimes this is deposited on the print and creates big blobs, often brownish color, and sometimes it just causes strings when moving from one to another part. Here too: it is rare in PLA, but common in PET, and printing slow, cool and in thin layers reduces it, but does not eliminate it.

 

I haven't tried experimenting with retraction settings, so I don't know if that could help.

 

So my solution is post-processing: cutting them off, and then light sanding and polishing, or chemical smoothing.

 

[mamastoast 0]

The insect antennas can be sanded off or otherwise removed, but the printer is also dragging parts of the stringing "into" the print, which makes it difficult or impossible to remove 😕

So a general update.. I've been playing around with the retraction settings, print temperature and speed according the advice I've found in various discussion threads with very little effect.

I've made a test file with two 2 color towers, which doesn't seem to suffer from the stringing, so it seems to be the complexicity of the print file that worsens the effect.

Edited July 29, 2021 by mamastoast

[geert_2 558]

I would say, try to minimise nozzle pressure and leaking by printing at the slowest possible speed, lowest temperature where you still get good flow, and thinnest layers. That should reduce the defects, or at least make them smaller, less visible and easier to remove. And then sanding and polishing...

 

Could you show us a completed and post-processed ball? It looks like a nice design.

 

[mamastoast 0]

I've done just that, not sure If I've reached the minium, but I've set the secondary color to print at a very slow speed and it appears to improving the result... It hasnt gotten super far just yet but it looks cleaner at it's current stage than previous attempts

[mamastoast 0]

[mamastoast 0]

[mamastoast 0]

It's essentially a small container. Printing the Screw thread as a seperate object so that each side can be printed flat on the print bed