1 Topic by AndersE (edited by AndersE 2015-01-30 23:13:02)

  • AndersE
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Topic: General filament extruder problem (homemade not filastruder)

I have a homemade extruder that has worked perfect for ABS. Excellent diameter tolerances and speed.

2 heatzones separately controlled by PID controller. 20mm diameter barrel and 20mm auger. Total lenght of barrel+heaterzones is about 20cm.
Auger run by a 1/4hp motor controlled with a variable frequency drive with TOTAL control of motorspeed regardless of load.


But as i have moved on to PLA problems came quick.

I run vertical, and have tried 45degree tilting, but filament comes out all between 2.20-2.8 no matter what i do.
It goes in constant waves at about 1-1.5m.

Cooled by a big 120mm fan, just right at the nozzle. I have tried ducting airflow, no ducting, one 120mm fan and two 60mm
fans direct after the big and coiling to the floor. No difference.

I have a homemade winder that goes on/off controlled from a readingfork the filament goes through. Thought first that it was becuase the on/off'ing of motor and swinging filament , but coiling to the floor is the same.

Predrying PLA for 4-5hours in oven, tried both with and without PLA colorant.
Different speeds and temps but the same waving in diameter, just different lenghts. Always consistent waving.

Read a hint that auger perhaps too far from nozzle so i tried an auger that was longer (end 3-5mm from nozzle)(previous auger ended 30mm from nozzle) no difference.

Tried cutting auger at 45 degree angle at the tip (previous 90 degrees(straight cut)) no difference.

There is ONE thing i think is the cause of my problem, but i am not 100% sure.
If i take off the nozzle and run the extruder i can see that the molten plastic is slowly pulsating out from the heater.
I am not sure WHY it does so, and if this could be my problem (varying pressure?) or how to fix it.

Or do i have too short barrel?

Anybody have any tips? Or am i the only one who have experinced this?

I don't want to give up because i like to print with PLA much more than ABS.

I am uploading a video to youtube now but it will take more than an hour to upload sad

2 Reply by elmoret

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Re: General filament extruder problem (homemade not filastruder)

What temperature(s) are you extruding at?

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

3 Reply by AndersE (edited by AndersE 2015-01-31 16:26:47)

  • AndersE
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Re: General filament extruder problem (homemade not filastruder)

I have tried from 170 to 185c. But i don't think it is the real temps at the nozzle. 185-195 works great with ABS in any case.

The thermocouple is mounted at the side of the heatchamber inside a drilled hole with thermalgrease.

http://youtu.be/k0BHMNOmKqM

Edit: i am going to try even lower motorspeed and lower temps today. I have been running motor over 9-10rpm..
so maybe it's that.
ABS i run it at 12-20rpm without problems.

4 Reply by elmoret

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Re: General filament extruder problem (homemade not filastruder)

170c might be a bit warm. I'd try lowering that a bit.

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

5 Reply by IanJohnson

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Re: General filament extruder problem (homemade not filastruder)

I have to keep the Filawinder as simple and easy to make as possible, but I love how you've printed everything possible on yours, including the threaded rod and timing belt.  I see the endstops and the lever on the servo, but how are you changing the direction of the guide rod?

6 Reply by AndersE (edited by AndersE 2015-01-31 20:23:09)

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Re: General filament extruder problem (homemade not filastruder)

Hehe.. very simple actually. I made a selfreversing "gearbox". The servo just pushes the gear-assembly back and forth to engage different gears. When winders started to appear i thought they all were too complex, i thought it could be done without arduinos, sensors or other stuff.
First i designed a winder using the selfreversing screw that JUST when i was finished Hugh Lyman had thought of the same solution and already posted it on the net. So i thought i should do something else, and came up with the selfreversing gearbox.

I also had (not anymore) a slow starting/stopping circuit for the motor, but the board blow and i didn't make a new one .
Now it just start and stop.

The threaded rod has 3mm pitch, but should be 2.85 instead (i made it for 3mm filaments).

The timing belt was originally for toothed gears, but the belt slippd all the time, so now i have crowned wheels instead. They never wonder off.
The belt is ninjaflex.

7 Reply by AndersE (edited by AndersE 2015-02-01 23:06:40)

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Re: General filament extruder problem (homemade not filastruder)

I think i have found my problem. I halved the speed today to 8rpm. I had been running same speed i did for ABS (12-20rpm).
I extruded about 25meters today for testing. And suddenly i get 2.3-2.4 variation only, at 170c temp.

So it seems i have run motor to fast. I will have to do some more testing.

I really hope this was it.. and some tweaking should get it better.

On the left, old filament, right is the new extruded with 8rpm.

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8 Reply by elmoret

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Re: General filament extruder problem (homemade not filastruder)

Very nice! Halving the speed doubles the cooling, so that probably helped.

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

9 Reply by aleksi

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Re: General filament extruder problem (homemade not filastruder)

very nice machines you got there smile Have you made the designs for your winder  available?