Problems with printing self-made filament

[3D-TH 0]

Hi,

I was trying to print some self-made filamet but experienced some problems improving the printing quality. The filament is not ideal since it doesn't have a consistent diameter which is probably the main reason for an inconsistent extrusion. I was trying some different temperature settings and also a temperature calibration tower. The problem is that i have to find a good starting temperature for the first layer so i can try different temperatures in one printing session, otherwise the first layer of the temperature tower is seperating from the heatplate and the layers do not stick together.

 

The thing i don't understand is why the outer lines of the brim i was printing have "good" quality and after 3-4 lines the quality rapidly declines (See picture).

 

 

Anyone experienced similar results when printing ? What is the reason for that? Can i change my printing settings to have the quality of the first 3-4 lines for my whole printing process?

I was thinking that maybe the filament for the first lines remains longer in the nozzle during the heating process which is the reason for the improved quality?

 

Thank you in advance for your answers

 

 

[Smithy 1,144]

First of all, I would cross-check it, with another filament, if it is ok with a "normal" filament, then you can be sure that your self-made filament is the root cause. A consistent diameter is very important to avoid over and under extrusion.

[3D-TH 0]

7 minutes ago, Smithy said:

First of all, I would cross-check it, with another filament, if it is ok with a "normal" filament, then you can be sure that your self-made filament is the root cause. A consistent diameter is very important to avoid over and under extrusion.

 

The printing quality with normal fimalent is just fine, I tried the same tower with ABS.

I just don't understand why the first lines are pretty good quality with the self-made filament when the inconsistent diameter is problem for the bad quality.

Edited May 14, 2019 by 3D-TH

[Smithy 1,144]

That's a good question, I don't know, but due the fact, that it is working with another filament, there must be something wrong with your filament. Maybe it is not only the diameter, but also the filament (material, mixture) itself. 

[gr5 2,172]

I have seen this exact problem with water absorbent filaments (nylon and PVA).  I have never seen this with PLA or ABS.

 

Nylon needs to be dried.  Leaving it in a "normal" dry room - even in the winter - it will absorb too much water within a day.  Some nylons are ruined within an hour on the back of the printer so you can't even do a 2 hour print.  Most nylons are fine for a multi-day print.

 

What tends to happen is the first cm or 2 of nylon gets nicely dried out when the nozzle is heating up and so the begining of the brim looks great and slowly gets worse.

 

Put a piece of your filament on the print bed and heat it to 60C with a towel over it.  For about 20 seconds.  Then bend it and poke it and then repeat at 80C and 90C and 100C and 110C.  Find out what temperature is likely to ruin the filament.  Then pick a temperature 5C cooler and put all the filament on the bed with a towel over it. If you are lucky you can dry the filament at 100C which dries faster. If it's a spool where it's hard for the heat to penetrate then heat it overnight.  If it's just 10 meters then an hour should be enough to dry it out.

 

Nylon is a common plastic.

 

Did you know what types of plastics were in your filament?  Did the plastics have recycling numbers on them which gives you a strong clue?  Or is it just random plastics?

[3D-TH 0]

Thank you for your answers!

 

My filament is ethyl cellulose, a cellulose ether. It is pretty hydrophobic and should not absorb moisture that easily, but i will give it a try. Since i only got a few meters left the drying-process shouldn't take that long.

 

When printing i also noticed that the extruded filament shows something like air-inclusions. Some extruded lines have more inclusions, some have less. Is this linked to the wrong temperature or could it also be connected with some water absorption?

[geert_2 557]

1 hour ago, 3D-TH said:

Thank you for your answers!

 

My filament is ethyl cellulose, a cellulose ether. It is pretty hydrophobic and should not absorb moisture that easily, but i will give it a try. Since i only got a few meters left the drying-process shouldn't take that long.

 

When printing i also noticed that the extruded filament shows something like air-inclusions. Some extruded lines have more inclusions, some have less. Is this linked to the wrong temperature or could it also be connected with some water absorption?

 

Bubbles are caused by gasses, could be water, could be others. Ethylcellulose, does that contain alcohol, or chemically bonded alcohol, ether, or something similar? If so, could it be that the alcohol/ether evaporates, or the compound is broken down into its basic substances (alcohol + cellulose, or whatever the composition is)? That might explain both the bubbles and the poor extrusion / clogging.

 

Maybe you could heat a bit of filament to the same temperature with a soldering iron, or on the outside of the nozzle (not inside, so you don't clog it), and see if and how it decomposes and degrades? Or google for how this material breaks down and burns?

 

PS: what is the purpose of printing in this material?

 

[3D-TH 0]

Good thought, but to my knowledge this shouldn't be the case. Maybe it could be water if the filament acutally absorbed moisture, I tried drying it yesterday for 1 hour at 100°C, but the printing results were the same... Maybe i have to dry it longer, but i guess my best option is to make filament with a consistent diameter. I will try heating the filament outside of the nozzle, maybe I get some useful information out of it.

The purpose of printing it is a pharmaceutical application.