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Poor quality support structure

monoprice Monoprice_mini monoprice_select_mini

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I think I have a hot end that needs cleaning, but it's hard to tell.

All OUTER walls of my parts come out great. I just put a brand new nozzle on and things look pretty good. However, when printing internal or external support, the extrusion is very lumpy. It's a bit hard to see in my picture but the infill is absolutely not solid and you can see the printer struggling to actually extrude anything. Not sure why outer walls are fine and inner ones are garbage. Printed a different part and I saw black flecks on a big solid chunk of the print so I'm wondering if I need to do a deeper cleaning. I tried the atomic yank method a few times but with no luck.

Any ideas?

Here is a picture of what I was seeing

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What type filament (i.e. PLA, ABS, etc)? What temp are you printing at? The black flecks concern me. Melted filament stuck in the heater block/nozzle will degrade over time. Another thing to look at is the heat break. Pull that and check the PTFE tubing. If that is damaged, it could affect extrusion quality. If it is damaged, you could buy a new heatbreak from gigdigit.com or just replace the PTFE tubing. It is just 2x3mm PTFE you can get from Amazon or eBay.

I'm using PLA, printing between 200 and 210 C (PLA is usually hatchbox but I am testing out amazon basics right now). I'll see if I can grab pictures of the black flecks for your input.

Heat break could be an issue. The PTFE looked fine, but I didn't examine the heatbreak at all.

The top of the old nozzle I replaced looked like it had bits of corrosion on it but the black flecks showed up after I put a brand new nozzle on.

I think there is a misunderstanding. The PTFE tubing I'm talking about is inside the heat break. Pull the heat break and look at the end that screws into the heater block. You should see a small PTFE tube. It is smaller than the PTFE Bowden tubing. That is what I am referring to. If it is damaged, then you can have problems. The temp is good (I print at 225 but never start the hotend till everything is ready to go). I also buy Hatchbox if I can get it in the color I need.

Ah, yes, I haven't pulled the heat break / hot end off. I looked at the PTFE tube inside (NOT the filament feed tube) and it seemed clear all the way down. I think a more detailed teardown is in order.

also, I'm seeing some PLA seeping out from above the heating block, I'll grab pictures and post here. I just changed my infill settings to connect the infill lines, hopefully that will be an improvement, but the PLA coming out of the heating block seems a much bigger issue!

So i completely disassembled my hot end. Turns out, the threaded bit of the nozzle I replaced my original nozzle with is SHORTER by a few threads. Not sure if the PTFE tube in the heatbreak is supposed to be in contact with the nozzle but there was definitely room for the PLA to just sit in the hot end between the nozzle and the heatbreak. I need to clean out the heating element completely as the threads are covered in PLA. After that, I'll try a nozzle with the same shaft length as the original. Beyond that, everything looks good and clean.

Don't forget that when you mount the nozzle, you need to follow the following procedure:

  • Screw in the nozzle until it hits the heatblock
  • turn back at least half a turn
  • screw the heatbreak in until it sits against the nozzle
  • mount everything
  • heat the nozzle - minimum 240°C
  • now tighten the nozzle against the heatbreak while heated

If you don't follow that sequence, you will always suffer leakages.

Hey desrtfx, so I did this exact procedure last night. took everything completely apart and then reassembled following a nearly identical procedure to the one you listed above. leakages seem under control now but still getting poor infill quality.

my new hotend for my CR-10 arrives today, I'm going to see how that works and do a teardown on the old one because I was having similar problems.

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I saw the same thing last print i did. Wonder if it might have to do with infill speed settings as well as a dirty throat / nozzle.

So I think it's a dirty throat. Nozzle is brand new.

I was having a similar problem on my CR-10 and am in the process of cleaning out the hot end (and also getting a brand new one).

Maybe I can lower my retraction length? I'lll give that a shot.

On my CR-10, the START of every extrusion comes out weak and ultimately gets better. I'm printing some large single walled objects and the first few inches are spotty and then it gets good again. The difference on the MP Mini v2 is that the outer walls look GREAT and its ONLY the support / infill that looks problematic. I'll try a few things on infill properties to see if i can make it any better.

Thanks for chiming in!

On my CR-10, the START of every extrusion comes out weak and ultimately gets better.

In this case, use a skirt to prime the nozzle.

yeah, so on my CR-10, each layer starts out poorly. i always do a skirt but as it starts a new layer, it takes a little while for the filament to get extruded properly.

as it starts a new layer, it takes a little while for the filament to get extruded properly

In this case, there are a couple things to check:

  • Retraction settings - you might be retracting too much/not priming enough
  • Again, the topic about the PTFE tube in the hotend (the picture shows that the PTFE tube goes all the way through the heat break directly to the nozzle). The Creality printers are notorious for the weak PTFE coupling hotend side. This can let the PTFE tube slip out a bit during retraction moves that can lead to a nasty clog right between nozzle and tube in the middle of the heater block. That was the reason why I bit the bullet and bought the Microswiss all metal hotend with hardened steel nozzle and Titanium heat break for my Ender 3. Never had a clog or extrusion problems since.
  • The extruder drive itself - it can slip since the spring on the extruder lever is quite weak on Creality printers. Here, a tensioner might help. I've upgraded to the full Aluminium extruder pictured in the link for the tensioner (and the tensioner). Currently, an upgrade to a Bondtech dual drive clone is in the works.
  • (unlikely, but possible) the extruder wheel is not fully fixed to the drive shaft. Also this can lead to bad layer starts because once the wheel catches on the flat side of the drive shaft, extrusion resumes normally (had that problem on my Anet A6 and it was a real pain to troubleshoot).

Difficult to tell what the actual reason could be, but these points are what directly come to mind. I am only giving some ideas, some points to check.

Hope that helps.

Ender 3 Extruder Spring Tension Spacer Fix