Need a hail mary before this printer goes in the trash.
I bought a Mk3 this summer as I need a reliable printer to run my business. I have been having issues with it ever since I got it. No matter what I do the hotend leaks. I know this topic has been covered extensively but I am praying someone has unlocked the code. My hotend leaks filament from the top of the heater block. I have followed all the Prusa assembly guides, forums, and advice about leaking and it STILL LEAKS! I HOT tighten the nozzle at 275, using a 2.5 torque wrench. I bought a brand new heater block and heat break and repeated the process and it STILL LEAKS. YES, there is a gap between the nozzle and the heat block. I don't know where else to go as I have followed all recommended procedures with brand-new e3d parts.
RE: Need a hail mary before this printer goes in the trash.
The one thing that threw me once with a frustrating filament leak was that there was some debris, not much and not obvious with a quick inspection with a dental mirror, on the lower surface of the heat break.
I ended up disassembling the hot end, cleaning off the end of the heat break with a file (ditto for the nozzle), chasing out the threads, and reassembling.
I think a lot of users underestimate the amount of pressure that's in there to force the molten filament out of a .4mm opening. If there's any other way for that molten plastic to get out, it will find it.
RE: Need a hail mary before this printer goes in the trash.
The best advice I can come up with is try to find someone who can physically check the hotend and observe your assembly process.
If properly assembled, it can't leak. If it leaks, it's not properly assembled. So, if you have followed all the instructions (and from from your description, you checked the key points), there's something, somewhere along the line where you're doing something inadvertently that's not correct but without observing you doing it, there's not much to add to all the advice you've already read. I used to work in a biochem lab (a long time ago), and sometimes someone just couldn't get an experiment to work even though they followed the "recipe" precisely, and it wasn't until someone else observed them doing it that they discovered the small deviation from the SOP that made all the difference.
Formerly known on this forum as @fuchsr -- until all hell broke loose with the forum software...
RE: Need a hail mary before this printer goes in the trash.
All of this is good advice. I want to rule out debris as it I am using a brand-new heat break, heater block, and nozzle. I wish I could turn to someone who can help but I think I probably know more about printers in this town than anyone. I will ask around though. I have a feeling that aluminum heater blocks are the culprit. The aluminum is so soft that even tightening the nozzle to correct torque is enough to deform the threads and cause leaks. Why don't they make these out of harder materials?
RE:
You can buy a E3D nickel plated copper heat block.
You could just but a complete, pre assembled E3D replacement hotend to get you back in business, then dismantle, clean, inspect, and reassemble the original hotend as a spare.
Better than tossing your printer…
Cheers
RE:
I have a feeling that this below is the Rest Of The Story here. (Copyright (c) ca. 1955 Paul Harvey) 😉
My experience after several nozzle changes, both using a printed torque wrench and a human-based torque measurement of 'two fingers of torque' 😉 is that the nozzle can be firmly secured without any damage to the heat block. Now if anything was cross-threaded or severely overtightened in the process, a leak could easily develop.
The aluminum is so soft that even tightening the nozzle to correct torque is enough to deform the threads and cause leaks. Why don't they make these out of harder materials?
RE: Need a hail mary before this printer goes in the trash.
IMO if the heater block is being deformed then too much torque is being applied.
Can I remind you, before you give up, the stock hotend is working correctly on thousands of printers. Not just Prusa, many E3D (after all it's practically a V6) after market replacements and many clones (often with inferior materials). The system works!
Have you live chatted with the help desk (email is slow)?
There is a world map of owners, perhaps you could get lucky and find somebody near you.