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Dual Color Prints

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Hi guys,

I'm trying to print a dual colored bear. I wanted the changing of color to take place at about 50% of the print. Cura showed that this print would use 3.2 meters of filament so I took 1,6 meter blue and 'welded' it to yellow filament with a lighter. But the problem is... I wan't the color change to be more graduate and not so fast like I got now:

Dual Color Bear

I saw some more dual colored prints on this forum which looked much more graduate. Is there a trick to do something like this?

 

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What you did is hard to do.

The gradual change is usually unavoidable.

If you wanted the gradual change you could try printing at a different temperature, though I don't know if it would work.

The only other way would be to join the 2 filaments on a sloping cut. Place them next to each other and cut both at the angle with the same cut so you match the angle.

Good luck

 

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Daid was quite succesfull with this by using the pause function in Cura. Simply pause at the layer height where you want to change, switch the filament (and flush out all the old color in the nozzle) and continue onwards from that point.

 

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You can get good results if you build a special type of "blender extruder". Basically you need a dual extruder that extrudes both filaments into the same nozzle. Then you can switch between extruders or run them both at the same time to blend the colors.

See this for details:

http://richrap.blogspot.ch/2012/08/3-way-quick-fit-extruder-and-colour.html

I recently switched from a white to a black PLA filament. With the Ulticontroller I chose "preheat PLA" and then just pulled out the white filament, then switched to the new black filament.

Then I started a print just to see how long it would take until the remaining white PLA would be completely gone. It took several minutes (bottom layer printing slowly) until the color shifted. But I also noticed that from time to time there would be small bits of white in between the black filament. This continued for one or two prints.

My conclusion is that if you want to switch colors "cleanly", you shouldn't only switch the filmament but purge any remaining old filament before inserting the new one.

I got a much sharper color change (completely switched within one layer) when I went out of my first filament spool in the middle of a print and just pushed in the new filament by hand while the print continued (it actually worked...).

It could also be that it doesn't matter "how" you switch filament but "between which" filaments you switch.

 

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Haha, thanks guys, but I wan't to emphasize that I DO want a graduated color change.

I've done serverel prints with the 'pauze at height' option, and with good clean separated colors. But I had hoped that with welding two colors directly to eachother, the change would be as graduated as possible.

I think it has something to do with the printsettings that the blending is relatively short. I printed this bear at 0.07 heigh, so the filament is moving very slowly into the nozzle. Therefore there isn't much mixing going on in comparrison with a faster moving filament. I was also thinking about cutting diagonally but this is very hard to do. Not only to cut it (PLA is quite hard) but then also to weld it back together...

Has anyone some more ideas?

 

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I've seen people just stuff segments of PLA into a bowden without welding them together as well. Might want to chamfer the edges ever so slightly though to avoid having them get caught on the edge of the teflon piece. And they'd have to be long enough so that they aren't able to rotate within the tube of course.

I have no clue if that would work but it couldn't hurt to try as long as you keep an eye on it so that it doesn't jam.

Also it depends on the print. If there's lots of infill where the head has time to purge, the visible change will be more sharp on the outside. A vase on the other hand would show a more gradual change.

 

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If there's lots of infill where the head has time to purge, the visible change will be more sharp on the outside.

 

Ah!! That must be it! Turn off infill.

 

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I think the gradient pieces you mean are the prints from Colorfabb. They use the transition material when they change colors in there production. Unfortunately they are not for sale...

I use a lot of colors in a print, putting them into the bowden before it starts printing. But this one was difficult because I had to 'reload' the bowden twice with the 'pause at z', it can print about one centimeter height with one load.

And the pla spreads a little on the cut, making it wider, so it is more difficult to move in the bowden.

Also noticed that the color transition from dark to lighter color gets more gradient than from light tot dark. Darker colors are of coarse

pla/pha 3 colors

 

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You're right Peggy, I meant the Colorfabb vase. And cool that they use a transition filament!

I've have 0 infill for that bear model but it does have 0.8 walls. I think I'm going to switch to 0.4 walls with the 'spiralize the outer contour' function enabled. And now from blue to red so maybe I'll put some purple inbetween.

I'll post a photo of the result.

 

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The transition range can be material dependent. I have a black PLA from swissreprap.com (also germanrep.com) that is incredibly sticky after color changes and needs a lot of cleaning extrusion. Generally, going from very dark to very bright colors may cause a longer transition interval.

 

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