Issues with Silk PLA

[ist165351 1]

Hi all,

 

I'm not entirely sure this is the best place for this kind of question, but I'm getting desperate trying to work with a specific filament of mine and am hoping there is some setting in CURA I can change to have it function.

 

I have a Robo 3D R1+ printer and it's been working (mostly) well for over 2 years. I still print regularly with a number of different PLA filaments (different brands as well) without any issues at all. However, I have this spool of "Silk Gold PLA" that keeps failing. I did manage to get some prints out of it in the beginning but now it seems to fail every time. Basically midway during the print I start seeing gaps in the print, and later on it just completely jams and stops extruding. The jams are never complicated clogs in the extruder: usually just pushing a bit manually is enough to have the printer working again.

 

So far I've tried:

1. Increasing the temperature (even slightly above the maximum recommended)
2. Messing around with retraction settings, even trying disabling retraction altogether
3. Reducing print speed
4. Drying the filament at 45º for 10h (lost 1g only)

 

I really like how this filaments look, and it was also my most expensive spool so I would really like to be able to print with it. It advertises as "Silk PLA"; googling around I get the impression that "Silk PLA" does have some distinctions towards regular PLA but I can't seem to find reliable information on this.

 

Thanks in advance,

Filipe Morais

[geert_2 557]

Some of these silk materials are a blend of PLA and other plastics, which causes the silk-effect. Although I don't know for this particular type.

 

If there ar no nozzle clogs and no overheating, have you tried how hard it is to unwind the spool? PLA is already stiff by itself, and gets even stiffer after time, which may make it very hard to unwind. It acts like a spring, trying to wind up again. Especially near the end of the spool where the bending radius is very thight. It might be just on the edge of what your printer can feed. If it is a bowden-tube printer, a tight radius also gives a lot of friction in the tube and printer nozzle.

 

In such cases I manually unwind a few meters of filament, straighten it by winding 15cm of it in the opposite direction around a skater wheel (7cm diameter), and then releasing it again. And then the next 15cm, etc..., until I get a few meters done. Then I loosely wind it up again on the spool. In this way there is no unwinding-resistance, and no friction in the bowden tube and nozzle, as the filament now has the same bending radius as the tube.

 

This straightening goes very fast, and I do it while the printer is warming up, so I don't lose time. Just be very carefull that the spool does not start unwinding from itself like a spring coil, and gets tangled up.

 

I am not sure if this is your problem, but it might be worth having a look into?

 

 

[kirkg 1]

I can't help but wonder if you found a solution to this? I'm also having issues with "Silk" PLA. It seems like it clogs the nozzle, so I'm wondering if a non-brass nozzle is the way to go for these PLA+ filaments.

[GregValiant 1,251]

I have had issues with silky PLA as well.  It would appear that it absorbs moisture much faster than regular PLA.  The layer adhesion is not good.  It appears to be "stickier" than regular PLA and does indeed slowly clog at the hot end.  But the colors are terrific.

 

Before printing with it I always dry it even though it is stored in a ziploc bag with silica gel packs.

I print it at 215 to get better layer adhesion.  I've tried to 220 but it gets real stringy.  Changing the Retraction settings indeed doesn't seem to help.

No matter the printing temperature, it still slowly clogs, and the filament within the bowden tube "accordions" in an attempt to fold itself over rather than feed which makes matters worse.  It then requires a pause, a hot pull, and trimming about 100cm of folded material to get going again.  This is with a hot end with a titanium heat break and brass nozzle.  It generally takes 2 to 3 hours to get to that point.  I've used silky filament from Matter Hacker and Sunla.  Both have the same issues.

 

But the colors are terrific.  The Sunla silver in particular looks like brushed chrome.  I have taken to adding pauses at about 2 hour intervals when printing with Silky PLA so I can do a quick hot pull and trim.  It's annoying but necessary for me because (did I mention?)...the colors are terrific.

[kirkg 1]

Glad to know it isn't just me. I bought a hardened nozzle to see if it helps with this filament. The couple of things I have printed look amazing. 

 

It does make me wonder if it would work better with a .6mm nozzle.

 

Once I finish my current printing project, I'm going to do some experimenting to figure it all out.

[GregValiant 1,251]

I started printing this Bender head with silky silver and the visor part came out great.  When I tried to print the front half of the head the printer struggled and then the layer adhesion jumped up and bit me when I cut off the supports.  I gave up and used whatever I grabbed and painted it silver.  It looks alright painted, but I wanted that silky finish.  .4 nozzle by the way.  I haven't tried with the .6 yet.

[thecooltool 1]

I am printing silk for the first time.
Did a test with a cylinder a few times and thought i had the temp right for 45mm feed.
I printed parts for 9 hours only to find that they still break at layers very easily.
I am currently printing some small parts (1 hour) at 30mm feed and 205 temp. Anything over 210 and the silk loses its sheen. (YOUSU Pearlessence blue).
I'll post back how this last run works out.

Edit 1: 205 @ 30mm is still not providing good layer adhesion. Trying 210 @ 30 feed bed is at 45.

 

Edit 2: 210 @ 30 was no better. Trying 195 @ 40 with 0.16 Z step.

 

Edit 3: 195 @ 40 @ 0.16 is worse. Sheen is great.

I do not think there is a way of making this better with this brand of filament.
It is a close color match to the BLV rail kit I installed and was planning on reprinting the cable chain and other items I added using this silk. As it is.. I wont waste my time. The cable chains wont make it trough assembly.

Sorry folks.. I tried.

Edited September 28, 2021 by thecooltool
typos

[GregValiant 1,251]

My current Silky profile is to print at 215 and at 60mm/sec but run the outer walls and top skin at 35mm/sec.  The hotter temp makes the layer adhesion noticeably better (still not great) and the lower speed keeps the sheen.