Today I'm going to pretty much be giving you an opinion, but not just any old opinion,
my opinion which does come with experience, and it's OK to disagree with it.
My opinion is that cold pulls don't work.
Now if you're unsure what a cold pull is, the idea behind it is to yank the filament
out of the hotend at a lower than operating temperature and this cleans the nozzle.
It's become some kind of internet mythological process that you're supposed to do if your nozzle
gets blocked up, but I've owned 4 printers over I'm not sure how many years, probably 3 at this
point but I don't keep track, but in all this time, all I have won from trying to cold pull
is the grand prize of filament snapping in the nozzle and then a full disassembly of the hotend.
And let's not talk about flexible filaments!
I mean they might work with direct drive hotends but this is not general advice then in
2021 when I think we can safely say that the majority of printers are bowden based.
So what I do want to discuss,
point out, state the obvious in this video is how to actually deal with a clogged nozzle.
In my experience.
The method to unclog a nozzle somewhat depends on how it was clogged in the first place. I find
that most clogs are a transient event, caused by what appears to be filament just sitting around
in the nozzle for too long and then being uncooperative when you want to extrude them.
This happens a lot if you have an error in a print, stop it,
but end up with the hotend still at temperature,
because normally the end gcode retracts filament, but not if you stop halfway through a print.
These are pretty easy to fix actually so no need to panic
and start poking around. Just raise the temperature and send a long extrude command,
say 20mm, either over the panel or octoprint or whatever you have.
The hotter temperature and extra pressure almost always solves this and you can carry on.
Slightly more difficult is a blockage due to something that shouldn't be in there.
You should always keep your filament in bags when it's not in use because dust can build up
and believe it or not can cause a gross blockage,
I don't have an example thankfully and I'm not going to try to reproduce this.
The solution in this case is to get yourself some of these things. They usually come with
cheap nozzles, and my ender 3 came with 2 of them too. It's just a case of doing what I
said a moment ago with temperature and increase the pressure on the nozzle while poking around
and before you know it you'll have whatever's in there, out of there.
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The third and most difficult to solve problem is actually an installation problem.
When changing your nozzle you should do this hot meaning heat up the hotend to 200C,
at least when it comes to taking the old one out, but the contentious topic is about putting
the new nozzle in. I'm a fan of doing it while the hotend is still hot mainly out of lack of patience
but I've also never come across this issue myself either so perhaps that's why.
(A side note that you should take all necessary precautions when handling a hotend at 200C)
The issue is, allegedly, due to a gap between here, the top of the nozzle, and here, the base
of the PTFE tube that is preinstalled into the tube that meets the nozzle. If you have an all
metal hotend you don't have this but you're also more likely to have the problem unfortunately.
What happens is called "heat creep" where for reasons beyond the scope of this video, filament
that's semi molten is allowed to fill any of these gaps and clogs too high up to be able to clear.
But don't panic, I mean, I personally have never experienced this at all, ever. Not even with some
of the really crazy things I do on this channel. That's the problem with the internet,
it's hard to know how common a problem is from the number of people who talk about having it.
If you are having a lot of problems with heat creep then I'm not sure what to suggest other than
I guess it might be a hardware fault causing it, or perhaps it's the way you're fitting the nozzle.
So there you have it. Nozzle clogs, almost always simple to solve. If you have an opinion that
doesn't match mine then we can argue in the comments, otherwise, thank you for watching!