Prints suddenly turned hideous...
Hi. I'm still pretty new to using my i3 MK3s... but despite a bit of a rocky start, I have had some success with it.
I'm printing a couple items that are intended to be gifts. As such, the appearance is of the utmost importance. I'm using this filament: https://www.amazon.com/gp/product/B07CBN28K9/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1
I was able to print pretty well with this stuff right off the bat, and found the sweet spot to be about 210c - 215c. I slowed the print speed down to 2500 and the xy movement to 900, and that seemed to produce a really clean, attractive texture to the exterior.
I then went on to print a few parts for work, using the Prusa silver PLA. Those seemed to go okay. I wasn't obsessed with the appearance of the exterior texture, since they were just functional pieces. As soon as I was done, I went back to the pink stuff, and I could not get a decent print out of it... even with the same settings and the same STL. I've tried tweaking nozzle temperature, retraction settings print speed, x/y movement speed -- nothing helps. Every time I print this now, I get these ugly, scaly horizontal lines that randomly occur. I've wasted days trying to get this to look good again, and I must have burned through half the spool trying to get this fixed.
The only weird thing that happened, when printing the Prusa Silver, was that I had a nasty jam in my PTFE tube. I've replaced the tube, however, and the machine seems fine. I'm sure it is in there correctly. Just to be sure there was nothing weird going on in there, I performed a couple cold-pulls, and they came out just fine as well. No crud. The nozzle is not plugged, I can get the acupuncture needle through without any problems. I don't see how this episode could be responsible... but I thought I'd mention for good measure. I have recalibrated the printer after replacing the tube, and have a spot-on, solid first layer on the test.
This picture illustrates the results I was getting. The finish was nice and smooth... it looked like brushed metal:
These are the sorts of prints I'm getting now... notice the weird scaly, horizontal, lines that occur at seemingly random intervals:
Anyone have any ideas on what is going on here? I've never struggled like this before with PLA... Since I have another 3D printer, and I don't have such issues with it, I'm assuming it has something to do with the Prusa.
This is my first post here, so I'm hoping the pictures came out OK. If not, I'll host them elsewhere.
Thank you very much for any help!
RE: Prints suddenly turned hideous...
Hmm... looks like it scaled the pictures... and I don't see any way to edit my post... I'll try again:
Good:
BAD:
RE: Prints suddenly turned hideous...
When posting images with drag and drop, it is as simple as selecting LINK TO : MEDIA FILE before pressing INSERT. The scaling becomes a non-issue.
I slowed the print speed down to 2500
The MK3 can't print at 2500, so no idea where you got this number from.
As for the surface artifacts, sort of looks like you damaged the nozzle with the needle. Also, taking the hot end apart to replace the PTFE requires some skill to put everything back together correctly. Did you follow the E3D-V6 assembly guide? If not, you probably want to go back and do it again.
As for why it jammed in the first place, are you printing in an enclosure? High ambient? And how do you know it was the PTFE that caused the jam? I ask because PTFE flexes and generally - by itself - can't lock the filament in place.
Have you by chance simply tried using the Prusa default profiles? They generally produce very good prints with the most filament.
RE: Prints suddenly turned hideous...
When posting images with drag and drop, it is as simple as selecting LINK TO : MEDIA FILE before pressing INSERT. The scaling becomes a non-issue.
I slowed the print speed down to 2500
The MK3 can't print at 2500, so no idea where you got this number from.
Oh, it most certainly can. You just have to consider that we are talking mm/min -- not mm/sec. The default speed was 4800:
As for the surface artifacts, sort of looks like you damaged the nozzle with the needle. Also, taking the hot end apart to replace the PTFE requires some skill to put everything back together correctly. Did you follow the E3D-V6 assembly guide? If not, you probably want to go back and do it again.
I've considered this, but I just found it unlikely, because the artefacts appear at random. Sometimes between 30 layers or more (though usually within 10). Take another look at the pics. If the nozzle were damaged, then it seems like it would produce a consistently horrible layer. It doesn't do that... Since the Prusa i3 MK3s comes with a needle, and their support advised me to use it, I have to believe this is a generally safe procedure. I wasn't rough with it. And Yes, I'm sure it was put together correctly. I work with and repair things of this skill level all the time. The directions were pretty thorough.
As for why it jammed in the first place, are you printing in an enclosure? High ambient? And how do you know it was the PTFE that caused the jam? I ask because PTFE flexes and generally - by itself - can't lock the filament in place.
Yes, I think the temperature got to high. I had an issue on a PLA print with a large base that was curling up off of the print bed. I had read that could be caused by the ambient temp being too cool, or being exposed to a breeze. This made sense, since it was printing near the AC vent (which is in the ceiling, blowing down). So, I had put a box over the top to keep the breeze out (as was suggested), but I think I over did it and it got too hot. I called support and we tried to push it through by heating the nozzle high, and giving it a nudge... but nothing doing. She advised me to change the PTFE tube. When I got in there to look, it was definitely stuck in there... I think it just swelled up due to the excess heat. Since this was a 26 hour print, I wound up just blocking the vent entirely with a plug, and I got a good print after that. It was after this print that I went back to the silk media.
Yes, I have tried the default profiles. I do like the new slicer quite a bit, but I found the exterior finish more appealing using Simply 3D for this print... until these artefacts started to occur, of course.
I had wondered if these sorts of artefacts had vexed anyone else out there... but I guess not.
One thing did occur to me though, we have had some really humid days, and I left this filament out. I don't usually have a problem with PLA sucking up moisture... but this is the weird (I mean cool) satin media... so who knows what they put in it. Perhaps I should bake the filament for a bit... Maybe those artefacts are bubbles of steam.... probably worth a shot... If that doesn't pan out, then I'll try replacing the nozzle.
Anyway, thank you for your input. If anyone has any other ideas on what might be causing this, I'd love to hear it.
Thanks.
RE: Prints suddenly turned hideous...
Sorry - all my experience is with Prusa tools, and everything on the Prusa is defined as mm/s ...
RE: Prints suddenly turned hideous...
I've not had this issue on my mk3 but back when my cr10s was running with a bowden setup I used to get exactly the same looking problem and that was under extrusion as it was printing. The filament drive gear was slipping which caused uneven output.
When I changed it to a direct drive with all metal hotend the problem went away. So I'd be looking at anything that can cause feed issues. Hot ambient is one of the things that can cause that and I think the silk filaments are more prone to it than others in the first place.
RE: Prints suddenly turned hideous...
Random underextrusion - I am betting a loose Bondtech set screw