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Easiest way to tighten heatbreak, hotend and nozzle?  

Active Member
Easiest way to tighten heatbreak, hotend and nozzle?

Hey guys,

I'm kind of in a pickle and need to get my 3d printer running again for several projects, I haven't been running it since I have been getting filament leaks from the top and the bottom of my heat block, I suppose the heat break and nozzle are not tight enough.

Anyone know what the easiest way of re tightening the heat block in place with the heatbreak and nozzle would be? I know that people have been referring to the E3D guide for the hot end which I understand, just wanted to know if there's a fast way with taking the least amount of parts off and with cutting the least amount of zipties since I don't have many and it's very hard to get currently due to the COVID19 situation.

I notice that the thermistor and heat cartridge wires are a seperate ziptie bundle than the main sheath and was wondering if I could just cut those two zipties, take off a few extruder parts, and get very quick access to the hot end assembly in order to retighten while all the cables are still intact? Anyone know if that will work?

Also, I can't seem to find a guide to take apart the extruder for the mk3s, only the mk3, I'm guessing the reassembly and disassembly processes are similar/same? Anything majorly different?


Posted : 01/04/2020 6:36 pm
Trusted Member
RE: Easiest way to tighten heatbreak, hotend and nozzle?

 I've never had to do it on the MK3 at work (got an MK3s for home on the way) but have had to do it on my other printer that has an E3D V6 hot end.  I think you can get access to the heat block by removing the cooling shroud (and cooling fan?), like I said I've never had to take that off the one at work.

To do it on my other printer I used a pair of  small channel locks to hold the heat block and then tighten the nozzle with a small wrench.  The nozzle and the heat break butt up against each other inside the threaded hole of the heat block.

You've got to be careful to only grab the block, don't damage heater or thermistor or wires, and not put too much torque on the block or you can snap off the heat break (it's quite thin in the "break" area).  And you've got to do all that while the hot end is above the highest temperature you'll ever print at (made that mistake once and the leak came back when I went to print hotter). 

You can get away with doing this without a fan running if you have the hot end out of the printer and remove the Teflon tube, and be quick so the fitting that holds the Teflon tube doesn't heat up.  But doing it that way is only slightly less awkward than doing it while the hot end is on the printer with the fan running.  You are still dealing with parts hot enough to burn you really badly while being careful not to damage the heat break, making it a tricky operation no matter how you do it.


Posted : 04/04/2020 1:08 am
Trusted Member
RE: Easiest way to tighten heatbreak, hotend and nozzle?

There are good guides how to do it, take a look at the prusa support and help pages and you should find it.

A couple of points to be careful about based on my own mistakes.
Assuming you have taken apart the hotend and have the heatbreak, heater block and nozzle separate, when you assemble it one of the first steps is to screw in the nozzle and then unscrew it one full turn.
This part is important and what allows you to later hot tighten the nozzle later when (almost) everything is assembled again.

Next you screw in the heatbreak from the top until it until it hits the nozzle.
It is important you get it screwed in until it stops against the nozzle, if the gap is too much, your one turn on the nozzle wont be enough later.
Plus when you got it all back hotend should be firm and not wiggle around by itself.


If you ended up with leaks (as i did), it may be hard to separate heatbreak and/or nozzle from heater block and this makes it harder to do this.
In my case i had planed to replace the aluminium heaterblock with a nickel plated copper block anyway so i ended up buying a new heatbreak too (i never got the heatbreak out from the heater block after the leaks) and used that.


Again, lookup the guides provided by prusa and follow them carefully.

Posted : 06/04/2020 10:26 am
Active Member
RE: Easiest way to tighten heatbreak, hotend and nozzle?

In case anyone else is going crazy trying to get the nozzle and heatbreak screwed back in properly... The big answer I could not find anywhere in the Prusa help articles, forums, on youtube:

---> You may have a situation where you aren't able to tighten your nozzle and/or heatbreak properly, due to the heat break staying loose and not facing foward (aligning properly). The solution to this is:

  1. Loosen the three "grip screws" on the side of the fan,
  2. Push the heatbreak up into the hot end (using your wrench - it's hot!) and turn the heat break clockwise (with your wrench) about 45-60 degrees. This will rotate the metal pipe as well as the heat break,
  3. Retighten the three tiny grip screws on the side of the fan. Your heat break will now be facing off center about 45-60 degrees.
  4. "Tighten" the heat break counter clockwise about 30 degrees (this essentially moves it up the threads slightly, which gives you the runway you need for the nozzle to be tight but not touching the heat break).
  5. Now, screw in nozzle til tight, and you should now be able to get that ~0.5mm gap, then tighten heatbreak slightly counter clockwise.

This should leave you with a tightened nozzle with a tiny gap, a tightened heat break that is pushed up to meet the tube, and a heat break aligned straight forward, as it should. This solved my leaking filament and loose parts issue! Hope is helps someone else out there too!

Posted : 17/12/2021 10:42 pm
Honorable Member
RE: Easiest way to tighten heatbreak, hotend and nozzle?


Posted by: @frames

Loosen the three "grip screws" on the side of the fan,..

This thread is about hotend on MK3S printer, not on Prusa Mini.

[Mini+] [MK3S+BEAR]

Posted : 18/12/2021 8:49 am
Larry Tener
Trusted Member

I have solved all my issues with the E3D unit by installing a Mosquito hotend. It cost a bit, but there is no way I would ever go back, the ease and reliably of use and the quality of the prints were all I needed.

I have lots of E3D V6 parts of somebody would like them.

Posted : 27/12/2021 2:40 pm