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Printing flexible filament... any hints?

Posted by frankvdh 
Printing flexible filament... any hints?
December 14, 2017 10:28PM
Hi,

I've been asked to print an object using flexible filament. I'm a bit leary about that, especially with a Bowden setup on my Delta. Does anyone have any hints or suggestions to pass on before I leap into it?

Thanks

Frank
Re: Printing flexible filament... any hints?
December 15, 2017 03:14AM
The Bowden tube might be no problem, just don't use retraction. I always print two skirt lines to prime the nozzle and build up pressure.
The flex. filament I used sticked really good to blue tape. Almost too good...
Maybe raise the nozzle for the 1st. layer a bit to reduce "squish"-factor.
VDX
Re: Printing flexible filament... any hints?
December 15, 2017 04:01AM
... to get flexible filament "stiffer" you can freeze the spool and mount it into a cooled insulation, and/or cool the filament shortly before entry into the heater zone - so it won't squish so much while feeding.

One methode for cooling with cold air is a "vortex tube" - [en.wikipedia.org]


Viktor
Re: Printing flexible filament... any hints?
December 17, 2017 09:15PM
As I feared, I am having trouble with the eSun eLastic filament. I've slowed everything down to ridiculously slow speeds (0.1mm/sec -- What is a reasonable feed rate for flexible filament?) and it still jams in the extruder. I tried a different extruder with the same outcome. sad smiley It always seems to curl around underneath the drive gear and jam... see the video at DropBox [www.dropbox.com] (candidate for least exciting video of 2017!)

I'm thinking about printing something in PLA to fill the space between the drive gear and the extruder casing, but I think perhaps this is a symptom of some other problem. It doesn't take much pressure to push the filament through the hot-end by hand, but pretty much impossible (due to the floppy nature of the stuff) to push it through the Bowden tube and hot-end. If I maintain pressure, material does come out the nozzle, but *very* slowly, like oozing out. I'm using a 0.5mm nozzle, BTW. I do have black Bowden connectors which allow the PTFE to go all the way through them, so the end of the PTFE should be hard up against the heatsink and I don't think it's jamming in there. But of course I can't see in there. Bowden tube is maybe 600mm long.

Filament now in the freezer to try that idea.

Edited 1 time(s). Last edit at 12/17/2017 09:24PM by frankvdh.
Re: Printing flexible filament... any hints?
December 18, 2017 02:15AM
Quote

Filament now in the freezer to try that idea.

Will be interesting to hear your experience. I'm afraid of condensed water building up on the filament.
VDX
Re: Printing flexible filament... any hints?
December 18, 2017 02:28AM
... keep the cold filament inside a bag as long as possible ... some flexible filaments can get brittle, so be carefully while bending it ...


Viktor
Re: Printing flexible filament... any hints?
December 19, 2017 01:09PM
Tried the "frozen" filament... it came out of the freezer about as flexible as it went in, so it's no surprise that I had no success printing with it.

But I suppose that's good news for someone who's printing flexible stuff to be used in the arctic.

Now looking at modding the extruder to close off the escape routes.
VDX
Re: Printing flexible filament... any hints?
December 19, 2017 05:38PM
... hmmm - at which temperature was it? - depending on the material it could get brittle like glass below -10degC ...


Viktor
Re: Printing flexible filament... any hints?
December 20, 2017 09:42PM
Filament has to be fully "guided" which means a ptfe tube near the hobb.
in Titan they have a plastic guided part that guides the filament to prevent buckling
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