1 Topic by astrn (edited by astrn 2020-10-17 10:08:01)

  • astrn
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Topic: PETG extruding. Water cooling for barrel? Motor replacement?

Hi all,

Just bought a filastruder and trying to solve several issues I am having with PETG extruding which is my main material.
So far I have managed to extrude about half a spool of PETG but then the motor stalls about an hour later.

I already tried suggested methods here like drilling a wider hole for nozzle, increasing the temp up to 205C-215C, removing the barrel insulation etc. but they create their own problems as well.

I suspect several issues that might cause it. It might be a combination of all of it as well.

1. I am using powdered colorant that probably contributes lower viscosity after some time due to not evenly spread all over the pellets and collecting inside the barrel walls/auger in time, causing more pressure.
2. Barrel gets too hot near feeder due to increased temp (205C and up), causing too early melting and creating too much pressure over the motor.
3. Low torque.

Possible solutions that might fix.

1. Adding a water cooling loop with copper pipes rolled around barrel where its closer to the feeder that keeps the temp lower to avoid early melting. Cost is around 100 USD This might solve issue number 2.

2. Replacing the motor with much higher torque rated geared NEMA 23 stepper motor, about 40NM with speed controller driver, around 2.5 times more torque than default filastruder motor. I suspect if that might bend the barrel so it might need a beefier barrel build maybe as well? This might solve issues number 1 and 3. Cost is around 110 USD

3. Increasing the length of barrel/auger and/or replacing it with a proper plastic extrusion screw. Adding extra 1 or 2 heat zones with lower temps (180-190C for better viscosity control and reduce the overall stress to motor. I wonder if barrel material matters if it is made of stainless steel and polished or plated interior etc.? This might solve issue number 1 and 2. Cost is around 150 to 450 USD, depending of barrel/auger/heater combination.

I am still very new to filament extruding and some of these solutions probably wont be a good ones but its still alot cheaper than getting a filabot ex6 system which I am still considering to buy in future. But I wanted to give a chance to filastruder first.


Before I start making those improvements, do you think those might solve the issues I am having or any other suggestions?

Thanks.

2 Reply by Tin Falcon (edited by Tin Falcon 2020-10-17 16:41:52)

  • Tin Falcon
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Re: PETG extruding. Water cooling for barrel? Motor replacement?

First of all not an expert. Do not own a filasruder and have never used one.

that said the filastuder was invented before PETG became popular.
Full size industrial extruders have much longer barrels and multiple heat zones.
It seems counter intuitive to cool the barrel  IMHO you need t put the insulation back or improve it to keep the heat in the barrel.
The filastuder as designed is a bit slow sound like you may be a bit impatient with the production rate.
You do not want to increase torque  without beefing up the barrel and possibly the auger.
the whole reason torque is limited in the system is to prevent damage to the machine in the case of a jamb.
Have you tried running a batch without colorant or reduced colorant to eliminate that issue ?
you may try moving the heater slightly away from the nozzle. Although i would think you would want max viscosity at the nozzle.
also make sure the thermocouple is properly installed and you may want to add some heat sink material to eliminate temp errors in the system

A cheaper alternative to the filbot is the wellzoom

https://www.amazon.com/Wellzoom-Stainle … ag=mh0b-20
the filabot is a great product  but imho priced more for colleges research facilities and industry rather than the average hobbyist. 

hope this helps.

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3 Reply by MrFlippant

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Re: PETG extruding. Water cooling for barrel? Motor replacement?

I've had similar issues, so please post if you find a solution.
I'm interested in a higher torque motor as well. The Filastruder one is limited to 3 or so amps because the plastic gears will fail if you give it more power to overcome the stall at 3 amps. Ask me how I know. sad
I think one way to help reduce the problem with material softening too soon is to speed it up. I re-wired my Filastruder so that I can supply power to the motor from a separate supply, a 0-30V, 0-10A bench PSU. The motor will go a lot faster, but you can't run 30V to the Filastruder because the heater is not rated for that high of a voltage.
I managed to get a good 700g+ of PETG pellets from GreenGate3d extruded on my system before it got stuck, and I stripped another set of plastic gears in the motor by giving it too much power. I didn't let it run extra fast for long, but there were times when I had it going at 16-18V for extended periods. Now, I'm wishing I cranked it up and left it going longer.
I still have to strip it down and replace the gears and try to get it moving again. So frustrating.
If I could get metal versions of the plastic gears, I'd be happy. If there's a gear box, with or without motors, that I can replace it with, that'd be cool too.
I'd love some links to the gear motors you're looking at.

4 Reply by erosion139

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Re: PETG extruding. Water cooling for barrel? Motor replacement?

It has been said that shearing is the main culprit when it comes to extruding PETG, I was thinking if it were possible to alter the feed channel to reduce the likeliness or amount of pellets that end up being sheared between the auger and barrel. I have had my current draw go all the way up to 3.1 Amps without twisting the barrel (THIS IS NOT A GREEN LIGHT TO ALLOW THIS) or shredding my gearbox (yet). That being said, it is not a solution to just raise the allowed current. I am thinking there should be a way to 3d print an ABS sort of guide that will reduce the size of the opening of the barrel so that as the pellets go along they have more time to properly seat into the channels of the auger before approaching the actual barrel on the far side of the inlet. I will have to experiment with this, as I am sure there is some magical configuration that can do it. I will update here when I find a solution.