1 Topic by Capt Jack

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Topic: White pellets extruding grey/dark grey

My filastruder is working just great, as is my filawinder, but I'm having an issue with the extrusion color.

I'm using white ABS pellets, and it comes out white, then grey then dark grey.  Yesterday I pulled everything apart and noticed a bit of grey material inside the barrel.  I cleaned it out, reassembled and started extruding.

The first few hours it extruded bright white, then slowly turned grey, and now it is dark grey.  Am I cooking plastic in the barrel?  Is there something I'm missing?

I'm extruding at 178 degrees, I have a filter on the nozzle (best purchase yet!), so I'm wondering what the problem may be.

Is it possible that plastic is getting melted further up the barrel and getting cooked?

2 Reply by IanJohnson

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Re: White pellets extruding grey/dark grey

I've seen that when they've sat at temp for too long, or too hot.  Maybe 195-200 for an extended period.  I had a bad bout of gray recently, most likely from a few instances where I switched it on early enough to give it 30 min for the heat to soak in, and then couldn't get back to it for a couple of hours.  I was also using the beta motor and had trouble with it turning the barrel so I had the heat higher than normal.

I think once it turns grey, getting rid of it would be something like purging masterbatch.  Running a lower temperature will help clean it out, because the higher viscosity will cause the new plastic to drag more of the old plastic along with it.

3 Reply by Capt Jack

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Re: White pellets extruding grey/dark grey

Ian, the plastic seems to be just fine, it just turns grey. 

So, you're saying that when I see it starting to turn, I should lower the temp for a bit to "purge" it?  How much would you suggest I lower it?  I run my ABS at about 180.

Thanks!

4 Reply by IanJohnson

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Re: White pellets extruding grey/dark grey

I suspect the color change is from getting too hot, but we are monitoring the nozzle, rather than the melt zone.  Maybe try moving the heater band closer to the nozzle.  If it is far away, it will have to get hotter to hit the target temperature at the nozzle and may be overheating the plastic in the process.

5 Reply by elmoret

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Re: White pellets extruding grey/dark grey

To chime in, natural ABS is very sensitive to discoloration. For true white, you should be using master batch. What extrusion rate? 1.75mm or 3.0?

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6 Reply by Capt Jack

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Re: White pellets extruding grey/dark grey

elmoret wrote:

To chime in, natural ABS is very sensitive to discoloration. For true white, you should be using master batch. What extrusion rate? 1.75mm or 3.0?

Yes, I'm aware that it won't be "true white", but it goes from white to dark grey.  I really don't care what color my filament is, but I'm more interested in what is going on that is causing the discoloration.

I'm extruding 1.75mm.

7 Reply by elmoret

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Re: White pellets extruding grey/dark grey

At what rate?

I've left ABS (MG94) sitting for over an hour at 185C with no detectable discoloration. I wonder what the difference is.

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8 Reply by Capt Jack

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Re: White pellets extruding grey/dark grey

elmoret wrote:

At what rate?

I've left ABS (MG94) sitting for over an hour at 185C with no detectable discoloration. I wonder what the difference is.

I get around 6 inches a minute.

9 Reply by elmoret

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Re: White pellets extruding grey/dark grey

Hmm, that's low. Try bumping up to 185 or 190C.

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10 Reply by Capt Jack

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Re: White pellets extruding grey/dark grey

elmoret wrote:

Hmm, that's low. Try bumping up to 185 or 190C.

Ok, I'll try that.

Btw, I just realized how dirty my prior post sounds. Lol.

11 Reply by Capt Jack

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Re: White pellets extruding grey/dark grey

At 187 I'm now extruding at about 8 inches a minute. The color is also slowly fading back to white. Instead of extruding at 1.75mm, it's now at 1.45mm. I guess it shouldn't be an issue as long as I put that measurement into my slicing software.

12 Reply by elmoret

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Re: White pellets extruding grey/dark grey

300 microns seems like a lot for a 9C temperature change! Is the fan on? What's the ambient temperature?

You can always drill the nozzle bigger. I ship them slightly undersize because it is a whole lot easier to make a hole bigger than it is to make a hole smaller. I insulated the entire barrel, drilled the melt filter nozzle to 1.65mm, and I see 1.6mm filament at 190C, 22"/min.

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13 Reply by Capt Jack

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Re: White pellets extruding grey/dark grey

Well, here is where I'm at:
My ambient temperature is currenlty around 63-65F, and yes, my fan is on.

I have disassembled and reassembled the extruder several times, as it kept jamming up after a couple of hours of printing.  The filament would start normal, then turn dark grey and extrude so slow you almost couldn't see it move. 
In my last reassembly, I have insulated the entire barrel.  It extruded at about 9" minute at 187 degrees for about 8 hours before turning dark grey/black and coming to a halt.  I know that when I pull the end off I'm going to find a bunch of plastic stuck in the end of the barrel that will go about 2 inches up.
I thought that the heater was too far up the barrel, so I even moved that closer to the nozzel, to no avail.

14 Reply by elmoret

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Re: White pellets extruding grey/dark grey

That's wild. Are you using ABS? I'd expect higher flow rate with a fully insulated barrel at 187C.

When you assembled, did you check that 1/4" of the auger was sticking out of the barrel with the thrust bearing fully compressed?

Can you post some photos of your setup?

Can you independently verify temperature? Can you tell me what the settings are in the controller? I've had one other user discover that the wrong settings had been set at the factory.

http://www.sestos-hk.com/english/download/d1s-en.pdf

Let me know all of the values, from HiAL to Ep9

I've never seen behavior you describe in over 1200 hours of Filastruder operation so it is difficult to diagnose, but I will try!

Filastruder - the robust, inexpensive filament extruder
E3Dv6 All Metal Hotend - the premier 3D printing hotend

15 Reply by jason_

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Re: White pellets extruding grey/dark grey

I saw issues like this... the light---> dark gray transition and slow extrusion rates.  I assumed it was due to my thrust bearing goof and the auger and nipple tolerances being out.  Changed the auger and barrel out and I went from 5 inches a minute to over 20 and no more problem.  I feel like my dark gray problem was caused by the plastic over cooking because of too slow extrusion.  Not sure if this helps or not

16 Reply by Capt Jack

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Re: White pellets extruding grey/dark grey

Attached are pics of my setup.  I took it apart and pulled all that charred plastic out.

All of the controller settings match the default except the following:
M50:  150
P:  192
t:  55

Also, there is 3/4" between the end of the collar and the auger.  Not sure if I should decrease it or if that's correct.

I did check temp with another device and it's within range. Yes, this is ABS and I purchased it from your recommended supplier.

Thanks for all your help!

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17 Reply by Capt Jack

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Re: White pellets extruding grey/dark grey

Two more pics.

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18 Reply by Capt Jack

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Re: White pellets extruding grey/dark grey

After looking at my setup, I decided to move the on the auger up from 95mm to just under 92mm. This gives me a good 1/4" extension past the end of the barrel. This does being it significantly closer to the end of the extruder. Hoping that this will resolve my issues.

We shall see...

19 Reply by sathwika.ponnapalli

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Re: White pellets extruding grey/dark grey

Hello,

I am also struggling with the same issue with my filastruder. After extrusion for about 3 hours (filament was very light grey here), my filastruder got jammed, so, i took everything apart, cleared the stuck plastic in the barrel and removed the filter. Later, i tried running the ABS and extruded good filament (light grey) for about 5 hours. but all of a sudden the filament started turning grey to dark grey, and I also found some greyish metallic scraps in the barrel. I cleaned them for the first time. But, when I started extruding the filament I found more of it in the barrel. I tried flushing them out by running the filament for about 5+ hours, but it is of no use. Then i fixed a new filter expecting an improvement in the color, but still it did not work (extruded for about 3+ hours).
I am extruding at a temperature of 170c-180c and with 1.75mm nozzle.

Could you please let me know how did you tackle with this issue?