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Chris
(@chris-39)
New Member
Perimeters not connecting to each other

Hello,

I'm new to the forum! Happy to be here and hoping to get some assistance with an issue I'm having. Hoping to be more involved with the printing community as well 🙂

I'm having issues with one of my Mini's printing weak parts. It seems the issue stems from the perimeter layers not adhering to each other. Looking closely, it seems there is a tiny gap between the perimeters rather than them making one solid 4 layer perimeter. I'll have to get a good picture to show the issue next time I make a print. The prints are generally weak enough that they easily pull apart by hand. 

I believe the issue is hardware related because I have 10 mini's, and the same gcode files print very well on the other 9 printers. This has been the case with over a dozen different gcode files used on the printer with the same recurring issue. This printer did not always have this problem, it seems to have just started a month or two ago. 

I tried replacing the nozzle with no change. I've also increased the extrusion multiplier by 3% in prusaslicer to try to combat the issue, but still without any luck. 

Is there anything else that might be causing this type of issue that I might be overlooking? Again, it's only on one of my printers, so I'm assuming it must be an issue with the printer and not the gcode. 

Thank you!

Chris

Posted : 28/09/2022 3:14 pm
mark
 mark
(@mark-3)
Reputable Member
RE: Perimeters not connecting to each other
Posted by: @chris-39

Hello,

I'm new to the forum! Happy to be here and hoping to get some assistance with an issue I'm having. Hoping to be more involved with the printing community as well 🙂

I'm having issues with one of my Mini's printing weak parts. It seems the issue stems from the perimeter layers not adhering to each other. Looking closely, it seems there is a tiny gap between the perimeters rather than them making one solid 4 layer perimeter. I'll have to get a good picture to show the issue next time I make a print. The prints are generally weak enough that they easily pull apart by hand. 

I believe the issue is hardware related because I have 10 mini's, and the same gcode files print very well on the other 9 printers. This has been the case with over a dozen different gcode files used on the printer with the same recurring issue. This printer did not always have this problem, it seems to have just started a month or two ago. 

I tried replacing the nozzle with no change. I've also increased the extrusion multiplier by 3% in prusaslicer to try to combat the issue, but still without any luck. 

Is there anything else that might be causing this type of issue that I might be overlooking? Again, it's only on one of my printers, so I'm assuming it must be an issue with the printer and not the gcode. 

Thank you!

Chris

Since you have multiple Minis, try doing a cold pull on a good one and the bad one.

https://help.prusa3d.com/article/cold-pull-mini_126399

When you get to step 7 and you push the filament down by hand while it is still hot, you can feel if it extrudes easily or if it is clogged. You can compare the two units. If it is clogged and the cold pull does not fix it, replacing the hot end PTFE tube would be the next thing I'd try, then reassembling the hot end or even rebuilding it. I think they changed the instructions to decrease the chance of the PTFE tube being damaged.

Regards,

Mark

Posted : 28/09/2022 5:40 pm
Chris
(@chris-39)
New Member
Topic starter answered:
RE: Perimeters not connecting to each other

Thank you for the reply! I will give the cold pull method a try, and see if that improves the prints 🙂 If I'm being honest, I've never done a cold pull an any of my printers, though I have nozzle X on my MK3's, so cold pulls are not recommended for those so I'd just kind of forgotten about the method. Wish me luck! I'll report back tonight or tomorrow with how it went. 

Posted : 28/09/2022 7:31 pm
mark
 mark
(@mark-3)
Reputable Member
RE: Perimeters not connecting to each other

 

Posted by: @chris-39

Thank you for the reply! I will give the cold pull method a try, and see if that improves the prints 🙂 If I'm being honest, I've never done a cold pull an any of my printers, though I have nozzle X on my MK3's, so cold pulls are not recommended for those so I'd just kind of forgotten about the method. Wish me luck! I'll report back tonight or tomorrow with how it went. 

It's the push before the cold pull that will tell you if it's clogged. The cold pull may or may not help. You may just have to rebuild the hot end.

You can definitely tell when pushing manually if it's clogged or not. It feels completely different. It's a way to seperate extruder issues from hot end issues.

Regards,

Mark

Posted : 28/09/2022 7:38 pm
Chris liked
fuchsr
(@fuchsr)
Famed Member
RE: Perimeters not connecting to each other

Sure sounds like underextrusion, and Mark's suggestion to start with cold pulls is the most sensible troubleshooting step. If it's not a partial clog, I'd start looking at the extruder and make sure the idler is set correctly, the grub screw is tight, and there's no other obstruction in the filament path.

Posted : 28/09/2022 8:56 pm
Chris liked
Chris
(@chris-39)
New Member
Topic starter answered:
RE: Perimeters not connecting to each other

Thanks Mark. Makes sense that you'd be able to feel if there were a clog or not with the cold pull method before actually doing the cold pull. There for sure was no clog issue aparent in the hot end with how easy the filament pushed through, and I inspected when I took out the PTFE tube and didn't see any obstructions. With no apparent issue there, what would be the purpose of rebuilding the hotend? I'm not trying to avoid doing work on it, I'm just curious to the reasoning before doing it so I can understand better while doing it to help my understanding for this and future issues. I've always been a strong supporter of building the deepest understanding of how things work as possible so if something goes wrong it is much easier to figure out why and fix or improve it. 

Thanks!

Posted : 29/09/2022 7:08 pm
Chris
(@chris-39)
New Member
Topic starter answered:
RE: Perimeters not connecting to each other

Thanks fushsr, I'm following you on that. Makes logical snese to me that if there isn't enough extrusion that the culprit may be in the extruder since it doens't appear to be an issue with the hotend (unless I've overlooked something). I will look into the extruder next, specifically the idler, grub screw and other possible obstructions that you mentioned. 

 

Thank you!

Posted by: @fuchsr

Sure sounds like underextrusion, and Mark's suggestion to start with cold pulls is the most sensible troubleshooting step. If it's not a partial clog, I'd start looking at the extruder and make sure the idler is set correctly, the grub screw is tight, and there's no other obstruction in the filament path.

 

Posted : 29/09/2022 7:11 pm
mark
 mark
(@mark-3)
Reputable Member
RE: Perimeters not connecting to each other
Posted by: @chris-39

Thanks Mark. Makes sense that you'd be able to feel if there were a clog or not with the cold pull method before actually doing the cold pull. There for sure was no clog issue aparent in the hot end with how easy the filament pushed through, and I inspected when I took out the PTFE tube and didn't see any obstructions. With no apparent issue there, what would be the purpose of rebuilding the hotend? I'm not trying to avoid doing work on it, I'm just curious to the reasoning before doing it so I can understand better while doing it to help my understanding for this and future issues. I've always been a strong supporter of building the deepest understanding of how things work as possible so if something goes wrong it is much easier to figure out why and fix or improve it. 

Thanks!

The PTFE tube does not develop an obstruction. It frays at the end or shrinks so some filament leaks out into the hot end and gums things up there. I'd just replace it with the spare that comes with every Mini, using the latest procedure online. I think they improved the process to preload it. If that does not change things, then it may very well be the extruder. If it is adjusted too tight or too loose, it does not work right. The adjustment and cleaning procedure is also well documented on the Prusa site.

Regards,

Mark

Posted : 29/09/2022 9:28 pm
René
(@rene-4)
Eminent Member
RE: Perimeters not connecting to each other

You indicate that one of the ten mini printers has this problem.

My advice is to check with that printer whether the first layer setting is correct.

Posted : 27/10/2022 3:06 pm
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