Soft/flexible filaments

[BenTheRighteous]

I picked up a spool of Soft PLA from MatterHackers (http://www.matterhackers.com/s/store?q= ... a%201.75mm) and I just started trying to print with it last night. It prints successfully for awhile, but will invariably jam in the extruder before the print finishes.

I haven't found any advice for printing with this material specifically, but I've been treating it as if it's Ninjaflex. Apparently it's slightly less soft than Ninjaflex (http://www.matterhackers.com/store/3d-p ... quarter-kg - "If your printer has a bowden tube Soft PLA is the best choice for you.") so I would think it would be slightly easier to print with?

Anyway, I've lowered my print speed down to 8mm/sec for everything (perimeters/infill/etc) and I've tried flateric's trick of coating the filament with oil (he picked sunflower, I picked canola). The extruder is still mangling it.

I also found a post by guanu about modding the extruder (http://forum.seemecnc.com/viewtopic.php ... =ninjaflex) which I haven't tried, but I hesitate to perform mods that are irreversible.

Has anyone else gotten a flexible filament to work in their machines?

[guanu]

if you do my mod, on the black part you drill out to add the ptfe, use the 3mm side (basically flipping the black part of the extruder and using the other tube) its fully reversible... and with the mod it still works fine for all other materials as well, so its more of an improvement to the extruder than anything.. the black part has the 1.75mm side and the 3mm side... you can use that 3mm side and put the aluminum adapter on that side and use it with the mod

also with flexible filament, you want to lower your retraction... the fast retract and prime are what squeezes the filament through that gap, so lower retraction distance.

Guanu

[Renha]

Could anybody please show photos of jammed filament? I'll try to print with Ninjaflex soon, and I wish to know well my enemy before fight begins

[guanu]

its the gap between the idler attached tot he red lever and the black plastic feed tube.. flexible filament can bend and squeeze out that gap... so my mod basically just eliminates that gap by adding a piece of ptfe tube to replace the feed tube and I cut it at an angle so its right up next to the idler giving the filament nowhere to escape.. the main issue is with retraction with fast retract and prime, it creates pressure enough to cause it to bend out of that gap

Guanu

[BenTheRighteous]

Thanks Guanu, I forgot to mention that I'd already lowered my retraction settings to 0.

However, I had my first successful print last night! My suspicion was that perhaps the extruder motor was getting just hot enough to make the filament sticky, but not melt it - and that's why it would print for awhile before jamming, since the extruder started out cold. Then when the extruder heated up enough, the filament would start sticking to the drive gear and jam. So I scavenged an old PC fan and rubber-banded it to the extruder, and the print went off without a hitch! Woohoo!

I'll post some pictures later.

Guanu, do you think one could avoid drilling for your mod by using a 3mm OD tube? I found this on Amazon, but it's FEP instead of PTFE and I don't know how that compares exactly. I would hope since the length of tube would be 3cm max, it wouldn't make much of a difference...

EDIT: Forgot the link.

[BenTheRighteous]

You're right though, that gap between the drive gear and the black plastic is exactly where the jam was occurring. So even though I've printed successfully now, I still want to investigate the mod so I can print faster.

[BenTheRighteous]

So 5 seconds of Google-fu seemed to provide the answer:

Coefficient of Friction, Dynamic
PTFE: 0.05-0.10
FEP: 0.08-0.3

So am I correct in thinking that in the worst case scenario, adding 3cm of FEP tube would be equivalent to adding 9cm of PTFE, friction-wise? That doesn't seem too terrible.

Source: http://www2.dupont.com/Teflon_Industria ... mpare.html

[BenTheRighteous]

Here are those pictures I promised.

The problem:

Filament fed through bowden, but mangled at extruder drive gear

Remember I said the filament would feed successfully for awhile. Maybe 30-60 minutes or so.

Detailed mangle shot:

Mangled by drive gear

The solution - cool down the stepper motor:

Old scavenged cooling fan pointed at extruder motor

My best guess was that the extruder was heating the filament and making it sticky enough to grab the drive gear. This worked.

I'll get a more permanent fix going soon, I swear:

Rubber bands - the professional's choice

[Renha]

thank you for photos, i'll try to find water cooler for steppers to use same water circuit as for Kraken cooling (water is still cold enough after it)

[lightninjay]

My recommendation to you is the same as my recommendation to Dunginhawk. Take Guanu's advice from SeeMeCNC, lower the voltages on your extruder motor.

Here's my post referencing his, and including that I lowered my voltages even more than he recommended.

[BenTheRighteous]

Hmm, worth a shot! Have you found any troubles with the lowered voltages, especially with quick retracts?

[lightninjay]

None that I've been able to notice, and I'm printing a freakin' cello!