Good translucent flex suddenly becomes milky-white foam
Hi,
For weeks I have managed to print multiple parts with Flex filament (Flexfill 98A Natural filament 500g) on my Prusa i3 MK3, like the one on the left: a semi-rigid plastic, translucent enough to see the infill pattern inside, able to bend slightly (shore 98A, like roller skate wheels).
But all of a sudden, whereas files are same appropriate G-codes (exported from latest Slic3r) all my prints became ultra soft and foamy like the one on the right, with holes in walls. What is this problem?
Before that, I printed successfully many parts with PLA and ABS. Nothing has changed in-between: same ambient temp, same location for printer, same latest firmware. I've redone the whole calibration steps including z-level adjustment with PLA, checked both fans, that the extruder nozzle was not clogged (it was not), tightened or untightened the 2 screws of the idler pulley, etc. Without any success.
One weird thing I have noted though, just before all my print attempts became useless foamy parts, is that during my last semi-successful print with Flex, the printing process stopped several times, the printer each time believing there was a clogged filament. There were none. Unloading and reloading the filament, the print was resuming fine, just to block again for same reason a couple of minutes later. Then I discovered that the flex filament was at some point "stuck on itself" on the roll, a bit like a roll of Scotch tape, and the tension on the filament wire became too high for the idler pulley to unwind it and pull it down. I had to unwind the filament manually from the coil over several meters to unstick it. Do your own flex filament rolls act the same as mine? Did I get a faulty material (a filament that may have been stored incorrectly during hot summer)? Could such an issue make chemical reactions and transform the filament, that was initially very good indeed, in a piece of junk material?
Re: Good translucent flex suddenly becomes milky-white foam
thats classic "air-printing". you've got a partial jam or clog
Re: Good translucent flex suddenly becomes milky-white foam
Thanks for your answer Curtis! I thought of a jam too so I unloaded the flex filament and tried to print a few centimeters of PLA (new calibration) then ABS with no issue. Maybe I didn't see the plastic line is maybe thinner than before with them. I will try the needle unclogging process.
Re: Good translucent flex suddenly becomes milky-white foam
You should probably dry the filament.
And you can turn off the filament sensor to stop the unload/load filament screens.
Re: Good translucent flex suddenly becomes milky-white foam
I think too there may be a problem with the filament material, not the printer.
I cleaned the nozzle with the following procedure:
The PLA extruded fine, with same normal amount (diameter and shape) of melted filament as before.
Then I tried to print with Flex again. Same bad result. Except this time, the print seemed to start fine (strong translucent and semi-flexible), but quickly became soft white foam again after a few layers (3-4 millimeters). See picture.
How do you suggest to dry the flex filament? Put the roll on top of one of my radiators at home? EDIT: I've seen online that I should use my kitchen oven at the correct setting, i.e. set its temperature to right below the glass transition temperature of the plastic. What is the glass transition temp of Flexfill 98A Natural?
Re: Good translucent flex suddenly becomes milky-white foam
Apparently this would be caused by various factors, the worst being the increased ambient humidity in this winter season (this flex filament seems very hygroscopic).
I had also a problem with the extruder PID calibration (thermal runaway) that seems to be now gone since I removed and put back the extruder thermistor to check its cables (apparently ok - inner bad contact?).
Filament sensor must also be disabled while printing with such soft filament as it randomly bugs, asking to remove then reinsert the filament without jam nor clog. With this kind of issues, after 5 or 6 stops the print doesn't resume properly as the head starts to print in the air about 5 to 10 mm above the object 😕
But still after all this, the milky-white soft structure still appears every time I print, although more "acceptable" than the bad fuzzy foam of the pictures above. Alas I never get a translucent consistent plastic anymore, even though I heat the roll overnight on a radiator, play with the nozzle temp, as well as increasing the flow rate a bit and decreasing the print speed…
I am very disappointed by Flexfill 98A, especially as I had initially very good results with it for about 15 prints 🙁
Re: Good translucent flex suddenly becomes milky-white foam
I finally tried the kitchen oven thing. 4 hours @ 40 °C. Print afterward is worse than ever! 👿
Now it feels and looks exactly like the white foam protecting goods inside parcels (texture, color, softness). It is completely porous, made mostly of holes and weights like air!
Completely disappointed. This expensive filament is a piece of junk.
RE: Good translucent flex suddenly becomes milky-white foam
Hi, I also have the problem with flexfill98. I only get porous prints.
was there any solution for the problems here ?
best regards
Ralf