1 Topic by bobnojio

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Topic: any way to even out color consistency over several meters?

Noticing this a lot on my Red filastruder filament --

on larger prints you can notice Banding / color shifts every once and a while between layers (or sets of layers)

you can notice darker red, then a few mm height of lighter, then darker, etc.

I think one of my issues is that the colorant behaves differently than the pellets in the hopper, and sometimes tries to 'escape' -- gets pushed up to the top of the hopper, causing there to be a Pile of color in some lengths, and very little in others.

I have the melt filtered nozzle already, and that greatly improved my inch-to-inch color consistency, now Im just trying to work on my meter-to-meter consistency.

any help would be greatly appreciated.

2 Reply by IanJohnson

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Re: any way to even out color consistency over several meters?

The best bet would probably be to pelletize and re-extrude it. It means taking twice as long, but I wonder if the second run would extrude faster.  Your pellets would be twice as small as the original, so maybe they would pack into the auger more efficiently and deliver more plastic with each revolution.

Or run some masterbatch at a very high concentration, pelletize that and use it as your colorant from then on.  When you pelletize 1.75 filament you get very small pellets which will mix in more evenly, and having the pellets less concentrated means you can use even more pellets to get a 2% mix.

3 Reply by bobnojio

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Re: any way to even out color consistency over several meters?

so basically, get the Chunks of color into smaller pieces, for more even consistency?

4 Reply by elmoret

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Re: any way to even out color consistency over several meters?

The best thing would be to use powered colorant, or to more finely granulate (with a coffee grinder or similar) exisiting colorant.

The pros also sometimes extrude twice as Ian mentioned.

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5 Reply by bobnojio

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Re: any way to even out color consistency over several meters?

elmoret wrote:

The best thing would be to use powered colorant, or to more finely granulate (with a coffee grinder or similar) exisiting colorant.

The pros also sometimes extrude twice as Ian mentioned.

Would there be any risk of the powdered colorant Falling through the pellets, getting Pulled faster into the filastruder, and basically giving very rich color at the start and then running out soon after?

How would you get the pellets at the top of the hopper to have the same coloring as the bottom if its powdered?

on a similar note, how would the powder get pulled into the machine?  looking at mine, i have about a pellet's worth of Void underneath the auger at the breach, so theres definitely room for powder to 'settle' down in there?

6 Reply by elmoret

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Re: any way to even out color consistency over several meters?

Generally the powder covers the pellets. You put them in a container, shake well, and the powder sticks to the pellets more or less.

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7 Reply by elmoret

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Re: any way to even out color consistency over several meters?

Some discussion of powdered pigments here:

http://www.soliforum.com/topic/2123/col … sterbatch/

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8 Reply by IanJohnson

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Re: any way to even out color consistency over several meters?

My experience with powder was that it is easy to get too much and make the filament brittle.  I'm thinking it might matter how fine the grain is, too coarse might make brittle filament no matter what the mix is.  Also it is very hard to purge.  I finally resorted taking apart the barrel to clean it out.

I want to give it another try to a limited extent.  You can get mica powders, generally meant for adding a metallic sheen to soap pigments.  I thought it would be fun to try with filament, maybe together with masterbatch.  It doesn't effect the color, so it won't matter so much if it takes a long time to purge.

9 Reply by bobnojio

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Re: any way to even out color consistency over several meters?

IanJohnson wrote:

My experience with powder was that it is easy to get too much and make the filament brittle.  I'm thinking it might matter how fine the grain is, too coarse might make brittle filament no matter what the mix is.  Also it is very hard to purge.  I finally resorted taking apart the barrel to clean it out.

I want to give it another try to a limited extent.  You can get mica powders, generally meant for adding a metallic sheen to soap pigments.  I thought it would be fun to try with filament, maybe together with masterbatch.  It doesn't effect the color, so it won't matter so much if it takes a long time to purge.

Thanks!

im leaning more towards the coffee grinder / pepper mill approach... it would Chunk up the colorant into smaller pieces, but not necessarily Powder it.

10 Reply by Claghorn

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Re: any way to even out color consistency over several meters?

Somehow I'm now envisioning a motorized hopper attachment that keeps tumbling the pellets as they are waiting to fall into the screw. Something like a cement mixer :-).

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11 Reply by milehigh3dII

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Re: any way to even out color consistency over several meters?

A little mineral oil (not much at all) will help the dry pigment stick.  The issue I had with dry pigment is that sticks in the barrel and if I want to change colors, I need to tear down to really get it all out.

What I did do is start to take about a 50:50 blend of ABS/Acetone and get it to about like honey.  Then add in pigment.  I've gotten up to 33% of inorganic pigment (pretty low surface area and resin demand).  Mix it up and then put it in a ziploc bag.  Cut a corner off and squeeze it out like cake icing into aluminium foil.  The stuff is STICKY and will clump and clog.  I found the key is to go with pretty good squeeze and move the bag fast to leave a thin trail.  Let the acetone evaporate off over night in a vented room.  I then pull the threads off the foil and chop it up.  I've fed it into a whirring blender and also used just a kitchen knife and chopped it like celerey.

They key in the let down phase is to get the lay down pretty stringy-- near the thickness of the ABS pellets.  Then the chopped bits will be closer in size and not stratify in the virgin ABS resin.

Done two colors so far, about 750g each.  Seems to work pretty well.  The main issue is the lay down of the liquid.  I'm looking for some MEK to see if that helps the handling with more 'open' time. 

YMMV

12 Reply by elmoret

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Re: any way to even out color consistency over several meters?

That's awesome! Thanks for taking the time to do the writeup and sharing.

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