Consantly replacing hot ends

So I’m running into the problem which seems to be frequent with others - the nozzle becomes clogged in the middle of a print, and I start printing air. I’ve read and tried many of the suggestions made in other posts, and nothing seems to solve the problem - and every thread seems to end with “replace the hot end, they are cheap”. Well, I’m on my 4th nozzle in a week. Based on my consumption of filament, by the time I use up my $25 spool of filament, I will have replaced $150 worth of nozzles. That doesn’t seem that cheap…

I’m sure this isn’t what people meant, but it seems like I’ve tried everything else. It is definitely getting clogged. After the clog, I heat it up to about 225 and am able to push filament through. It often “curdles” at first, so I have to use a thin wire tool to clean out the nozzle - and then eventually I get a nice smooth flow. I also clean the entire nozzle with acetone until it’s completely clean. This wouldn’t be a big deal - if it didn’t happen every other job - or sometimes every job. The clog could happen 20 minutes into the job - or as long as 4 hours into it, which I think is the longest.

When I do change the hot end, everything works fine - for approx 15-20 hours of printing, and then I clog up again.

  • I’m not printing too close to the bed. My z-axis is at .25mm. Any higher, and it just won’t stick to the bed.
  • I calibrate every time, and at no point does the nozzle ever hit the bed.
  • I’m printing at 215 degrees, which is 15 deg higher than PLA should need.
  • The filament feeding is free - it is not getting caught, to where it can’t pull it in.
  • I’ve set the Zhop and retraction distance to 1mm as suggested.
  • I’ve changed out the filament (both are PLA from Snapmaker). I saw one comment that that’s the issue - but I’m having a hard time accepting filament that Snapmaker sells doesn’t work in it’s own product.

If it helps, I’m trying to print various objects from here: They don’t seem complicated.

I’m not sure what else to try - but I can’t realistically replace the nozzles every few days. And I haven’t seen much to suggest that nozzles, while they sometimes need to be replaced shouldn’t be something you have to do frequently. Certainly, not one per 50-100g of filament used.

Would appreciate any suggestions! Thanks!


Its the filament, I know its hard to swallow but if you have tried everything else, then its the filament. Now it could be your environment. The filament will absorb water and attract dust. So if your in a high humid area or a dusty environment that could cause your filament to go bad sooner. But the honest truth is that SM filament is cheap, buy a roll of hatchbox filament and see if you still have problems. Also make sure you check your e steps. Over extrusion can cause clogging as well.


This is beyond my experience, but I’m wondering:
Is there a temperature too high at which PLA will start to clog nozzles?

If the controller is reading 215C, and the thermistor happened to be in poor thermal contact with the hot end, could the actual nozzle be like 245? Would that cause clogs?

yes printing at to high of a temp can cause clogs but it usually takes extreme heat and you would notice some big issues with the part of the print that was successful. once had an issue with my ender 3 that caused the filament to get so hot it fused to the brass, couldn’t even get the nozzle off, had to get a whole new hot end. the biggest indicator would be a really strong sweet smell, like maple syrup kind of.

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I haven’t had a clogged nozzle since I stopped using SM filament


My understanding is PLA is normally 205 deg, which is where I started. I raised it to 210 then to 215 based on suggestions, to see if that resolved the issue. I don’t think it being too hot is causing the problem, since raising it 5-10 degs unclogs it. But at 220, it starts to smell, and at 225, I can see filament start to burn (some “smoke”), so clearly, that’s too hot to print.

My environment certainly isn’t dusty. It has been raining, so the humidity has certainly been higher. But if sounds like you’re saying excessive humidity can cause the filament to go bad - it was sealed until a week ago. And the second spool I tried was opened for 2 days.

Ok, so I’m seeing more support for changing the filament, so it’s worth a shot. I’ll try a spool of hatchbox as @Atom suggested. Any other suggested brands?

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I’ve heard good things about Prusament, haven’t used it myself though.

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Hatchbox has a good reputation.
I’ve had good success with Filamentone.
Just received a couple rolls of Prusa. They have a really good reputation. Looking forward to trying them.
Esun has a good reputation.
One thing to look at is the promised diameter consistency. The smaller the better. Prusa promises .002 on most of theirs. Anything .003 or better is pretty good.



Wow no kidding about the prusa tolerance, taken from their page:

That’s pretty tight tolerance. I also appreciate their attention to spool to spool color matching.

Interesting ideas, but at least where I’m looking it’s like twice the cost of Hatchbox… Boo.

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Hatchbox is only a couple bucks cheaper for the equivalent filament.
Shipping is free though where it’s $13 for two reels of Prusa.
Definitely not twice though.
I preferred when Hatchbox didn’t sell only through Amazon.
Hatchbox also doesn’t have the color blue I wanted.
If the Prusa prints better so I don’t have to do reprints the difference will easily pay for itself.


I’ve tried prusument galaxy black it it is awesome. I’ve also had good results with eSun pla+ and eSilk. Esun is quite cheap.


Had to change the hot end for the first time after it clogged while using the snapmaker black PLA. The end is sitting in acetone now let’s see if there is something to salvage there.

So you are aware acetone does very little to dissolve PLA, it is very affective on ABS so you will see alot of posts about it online(ABS being the other most common plastic used). But I have e never had it work on PLA and if you do some googling there are some well written scientific documents on why acetone will not dissolve PLA.

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Yeah, there was little effect on the hot end. Do you think I should just give up on this old head?

It’s a lot of work, but there hasn’t been a nozzle I’ve had to throw away because of a clog. It’s almost always possible to rehab it.

There are numerous variables that you should consider in your problem solving, here are two that hasn’t been mentioned yet in this thread:
1. Humidity:
PLA absorbs moisture - thus high humidity environment will affect you. Solutions: Store your filament with a desiccant (silica gel), use a dry-box (filled with dessicant) to store your rolls or vacuum seal your filament rolls with a desiccant sachet in the bag. Research online how to dehumidify filament (oven at low temperature)

2. Dust: My town is notorious for fine dust (mining)
I use a dust filter (Thingyverse ) with a sponge threaded onto the filament. I later printed two filters together (fused) and placed a microfibre cloth in the 2nd one.
You could also very easily just fold a microfibre cloth (such as used to clean spectacle lenses etc) a few times and clamp it onto/around your filament with a paper clamp allowing for free moment.

The one time I got a clogged nozzle I didn’t have my filters on. To resolve the clog required a cold-pull (cold-pull which worked perfectly.

Hope this helps!


Agreed, only time I had to throw away a nozzel due to a clog was when my ender malfunctioned and got so hot that the filament fused to the brass, but I had to get a whole new hotend and bowden tubing. Other than that a clog can be cleaned.

i actually did mention both humidity and dust

but thank you for going into more detail about how to resolve those issues :slight_smile:

Quite correct :slight_smile: I wanted to give him practical suggestions with more detail on how and why these 2 very common issues might apply with applicable easy solutions.
In the many months of waiting for my SM2 A250 I read many very useful articles that made my foray into 3D printing so much easier!

The ALL3DP.COM website has loads of useful articles, advice and reviews.

Happy making!


When a head is cleaned does it still function properly? (initially).
I have a problem with the reported temperature of the nozzle.
It jumps wildly sometimes as much as 15 degrees.
It has stopped printing almost every attempt.
The thermistor for the print head is just sitting in a drilled out hole in the aluminum block.
I am in the process of getting some heat sink cement. (aluminum filled epoxy). (shipping delays)
I’m gonna glue that thing into the hole.
This should create a more stable thermal bond to the head.
If the head still heats I wouldn’t get rid of it.

Will advise results.

@D_Kerarns Good idea. Although I’d recommend using an electrically insulating thermal paste, such as boron nitride. Typical aluminum epoxies are approximately 106 Ω.cm. Since the thermistor leads are approx 1mm apart, that would put a load between the wires of around 100kΩ. Since the thermistor itself is a 100kΩ load at ambient, that could affect the accuracy of the reading.

For comparison, boron nitride is >1014 Ω.cm