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jonjude

Feed motor "stammer" - loss of extrustrion

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Hi there,

After some time of reasonable results, I'm getting again problems of feed of plastic. I'm seeing that the

torsion and the twist on rolls of feedstock ( as purchased ) can be very high. Suffice it to say, you buy a roll

of PLA there's no chance of the PLA "wire" being straight, and without any twist. So I see regularaly the following :

** Feed motor extruder will jump and stammer, with visible loss of advance of the PLA wire, and loss of extrusion.

** Adjustements to extruder seem insufficient when rolol of PLA is a "tight" roll with a serious twist on the wire abd the advance screww can grind the wire.

I am toying with the idea of changing Feed motor component to one like seen on :

 

http://www.thingiverse.com/thing:15897

But there will still be feed wire torsion and twist - at least until someone starts seelig large diameter rolls. Is there no simple way to avoid feed-wire torsion/twist for smooth feed ?

Regards,

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Hi,

I'm seeing this, I think, because I'm using PLA that has a vicious curl on it. I've been running with

same motor setting since I got the machine. But it's gradually over latest usage, the

behaviour changes as I get to the end of a PLA roll, or now I have begun using a new roll but

one that seems to be more tightly wound on the spool, that I get this.

I'm trying to see if it's to do with too much friction at the toothed bolt. Maybe because can't advance through

hot end fast enough too ?

Just to know, before I do it, how will a motor setting change make that better ?

Regards,

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Hi,

So, maybe some more information needed ... maybe my description of the problem isn't enough

"jump" and "stammer" are still pretty appropriate adjectives but it's more of a growling noise, perhaps even grinding.

My interpretation now is it's the motor trying to turn and advance the feed wire but it's finding

resistance.

The question remains, what do people do about seriously curly/twisty PLA ... does anyone else have a problem ?

Regards,

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My interpretation now is it's the motor trying to turn and advance the feed wire but it's finding

resistance.

Ah, ok. My interpretation was that you stepper motor was missing steps.

The extruder mechanism should be able to cope with quite some resistance, but you need get the tension knob just right.

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If it isn't missing steps, it should grind a hole in the filament. Do you get that? If it gets too much resistance near the hot end, this will happen.

Open up the clamp and push by hand. 2-3kgf should be enough to get a snaking extrusion out of your hot end.

If you're afraid about the curl, take the spool and turn it around on it's axis. Not the one where it normally turns on. If that doesn't fix it, it's less than one turn, and won't do any harm.

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