Printing with Polypropylene (PP)
I have a core one+ and I've been struggling some with getting PP print quality up. I know it is one of the more picky ones so I've been going through calibration prints to tweak settings in Prusa slicer. I started with a generic flex profile. I did the temp tower and it seemed to have the best quality at 265 C nozzle temp (I left the first layer at 240 C as I've seen references that starting lower helps). I have the bed at 80 C and the nominal chamber temp at 30 C. I'm now doing a retraction test print and still getting the stringing. bumping the retraction length up to 2.5mm (retraction speed is at 40 mm/s and deretraction speed at 25 mm/s) helped some and so far produced the best result. However I still have some stringing at the lower part of the two towers. Is it unlikely to get rid of all stringing for PP or are there additional tweaks I can make? What settings have worked for others printing PP on the core one? Thanks!
RE: Printing with Polypropylene (PP)
Which brand of PP? What nozzle? I've had success printing Yousu PP. If you attach your 3MF file zipped I can load it and advise.
RE: Printing with Polypropylene (PP)
Which brand of PP? What nozzle? I've had success printing Yousu PP. If you attach your 3MF file zipped I can load it and advise.
Thanks for the help, hyiger! I'm using Sunlu PP Natural with a 0.4mm v6 stainless steel nozzle (to make the print food safe - I have some food grade epoxy as well). Here is my zipped 3MF file (it has 2 different types of retraction towers that I was printing serially): PP retraction test. I also tried printing an overhang test: PP overhang test. It was able to print but after about 60 degrees overhand, the quality tanked. I'm not sure if that's just to be expected for PP or if there is something I can do to fix that.
RE: Printing with Polypropylene (PP)
What kind of surface are you printing this on? Are you using PP sheet or tape?
Had a look at your profile.
Some suggestions:
- You need to turn off fans completely for PP or it will warp and cause layer adhesion problems.
- Other layers temp seems too high. I would keep it around 235-240
- You have chamber heating disabled. I run my chamber at around 45-50C to control warping.
- Also, I see you don't have shrinkage compensation. PP shrinks a lot. Using Yousu PP for example I measured 0.77% in XY which is more than ASA or PC
- Speeds are way too high. You have external perimeter speed set to 170mm/s, I would cut that in half. This will help with stringing.
- Retraction is too long (2.5mm), I would try 1.5 at the most
- Should increase the # of perimeters to 3-4 instead of 2 since PP is poor for layer adhesion (most brands I've tried).
RE: Printing with Polypropylene (PP)
Ok, let's try it that way. Here is the retraction test.
RE: Printing with Polypropylene (PP)
and here is the overhand test (I could only attach one file per post - although now that I think about it, I could have just put them in the same zip... oh well, too late... next time)
RE: Printing with Polypropylene (PP)
What kind of surface are you printing this on? Are you using PP sheet or tape?
Had a look at your profile.
Some suggestions:
- You need to turn off fans completely for PP or it will warp and cause layer adhesion problems.
- Other layers temp seems too high. I would keep it around 235-240
- You have chamber heating disabled. I run my chamber at around 45-50C to control warping.
- Also, I see you don't have shrinkage compensation. PP shrinks a lot. Using Yousu PP for example I measured 0.77% in XY which is more than ASA or PC
- Speeds are way too high. You have external perimeter speed set to 170mm/s, I would cut that in half. This will help with stringing.
- Retraction is too long (2.5mm), I would try 1.5 at the most
- Should increase the # of perimeters to 3-4 instead of 2 since PP is poor for layer adhesion (most brands I've tried).
I'm am using the PP sheet and I got some Magigoo PP that I've been using to make sure it sticks. I'm reading through all your suggestions. I have a couple questions / clarifications. For the chamber heating, I added some Start G-code to dynamically open or close the vent if I use chamber heating. I'm assuming you have your vent closed when you keep it at 45-50 C, correct? Also, I have start and end G-code in the filament settings to dynamically limit the max speed (I wanted that self contained in the filament profile) so it's not at 170 mm/s. However I did have it capped at 150 mm/s so still too fast so I'll adjust that. All great direction on things to try and you just gave me a whole new calibration to do going forward with the shrinkage (I hadn't seen that one yet). What calibration model do you use for that? Will it tell you what is needed on the Z axis as well as XY?
RE: Printing with Polypropylene (PP)
I just tried a print with all the settings you suggested. It definitely improved the stringing. I only had 1 string across the top of the 4 column one and a single vertical string on tip of one of the columns for the 2 column one. However it did turn the columns into stacked / spiral toothpaste instead of the defined cylinder / cone shapes. The base of them both were really nice, though so I think it is a step in the right direction. I could be completely wrong as I'm just guessing, could the distorted shapes have anything to do with z shrinkage? It just seemed to affect the verticals...
RE: Printing with Polypropylene (PP)
. What calibration model do you use for that? Will it tell you what is needed on the Z axis as well as XY?
I use Califlower MK2 for XY shrinkage and skew.
Z is a bit harder but I usually estimate it by printing a 100mm hollow cylinder with 2 perimeters.
RE: Printing with Polypropylene (PP)
and here is the overhand test (I could only attach one file per post - although now that I think about it, I could have just put them in the same zip... oh well, too late... next time)
What's ironic is that 3MF is actually a zip file already. However this forum only allow ZIP file attachments.
RE: Printing with Polypropylene (PP)
I'm assuming you have your vent closed when you keep it at 45-50 C, correct?
Yes, vent closed with a blanket on top for extra insulation.
RE:
I just tried a print with all the settings you suggested. It definitely improved the stringing. I only had 1 string across the top of the 4 column one and a single vertical string on tip of one of the columns for the 2 column one. However it did turn the columns into stacked / spiral toothpaste instead of the defined cylinder / cone shapes. The base of them both were really nice, though so I think it is a step in the right direction. I could be completely wrong as I'm just guessing, could the distorted shapes have anything to do with z shrinkage? It just seemed to affect the verticals...
For this kind of geometry you need to slow max volumetric flow down a lot and possibly enable a little bit of part cooling (like 20% fan). If you attach the 3MF I could fix it up for you. Basically the previous layers are not solidifying before the next layers are being added.
RE: Printing with Polypropylene (PP)
I don’t have much use for PP filament, but years ago I purchased a spool of Recreus PP to see how my MK3S behaved with this stuff. Recreus ships PP spools with a flask of dedicated PP glue, so you don’t have to use a PP plate or nothing fancy, just an ordinary PEI smooth plate will do. I printed only a few small parts (funnels mainly ) and then that spool has been left alone for years. It’s still somewhere around and probably the remaining glue is already unusable or dried up.
Anyway, the oddity with this smelly glue is that you must apply it on the bed, leave it dry for 10 minutes or so and then print with the bed at a maximum of 40C, No enclosure or high chamber temperature at all. Once the print is done, you heat the bed up to 60-70C and remove the prints while the bed is still hot. Kind of counter intuitive but it worked well Adhesion was excellent and no damage to the smooth plate. The only drawback is that if you print another type of filament on this plate first you must remove totally the PP glue, and it’s not as simple as a quick wash with IPA, because it’s not water soluble. You need a solvent like acetone or similar. Not very friendly for the PEI surface if this is done on a regular basis.
RE: Printing with Polypropylene (PP)
I use Polypropylene packing tape on a steel sheet. You can also buy sheet-sized PP stickers. I use it mostly to print funnels for resin printing and tools for dealing with resin. It's hydrophobic so doesn't need to be kept dry. Otherwise, don't really have much use for it. Once the INDX arrives, I would like to try printing inline hinges