Yes, it does need to
Okay, then in that case, that solution wont work unless the heatbreak is long enough to accomodate the missing thread.
Yes, the heatbreak has several turns of threads. Screwing it in and out 1/2 turn is fine. Typically they are not shouldered and this isn’t an issue.
Not from this printer, but it’s roughly aligned like that, and the heatbreak and nozzle are what bind together
From step 25 here https://help.prusa3d.com/en/guide/how-to-replace-a-heatbreak-heatsink-heaterblock-mk3s-mk2-5s-mmu2s_16104
With the other hand, screw the heatbreak with heatsink into the heaterblock from the opposite side until it touches the nozzle inside. Do not tighten anything by torque wrench at the moment.
Well then i would imagine you could still accomplish the spacer to put the nozzle at the expected height so that the auto calibration would still work out as expected, if you change the nozzle distance from the module i think that would cause problems no? im sure you could program them out possibly manual calibration etc
Not really.
Why? just screw the heatbreak in 1/2 turn to compensate for the 0.5mm distance, per your above cad view
I was under the impression that the tip of the nozzle needed to be exactly at the distance from the bottom of the module so that the prox sensor in the module for autocalibration can correctly determine where the height should be at for the nozzle to print and the z offset was just to fine tune where you wanted it to print from.
only turning the heatbreak in to compensate for the little bit of missing thread on top, without adding a spacer between the shoulder of the nozzle and the bottom of the module, will still make the tip of the nozzle 3mm higher than the nozzle would normally be
The final step of the calibration, with the card, sets the exact height in the machine. The exact position of the nozzle is not important as long as the proximity sensor triggers and it overhangs the cooling duct.
How do you figure. The overall length of the two nozzles shown from end to end only varies by 0.5mm… Are you looking at the distance from the top of the shoulder to the heat block, if so that distance is not important.
The shoulder of the nozzle butts up against the bottom of the of the module when you thread it in
If you thread it in further, because the shoulder is lower, then it will thread up higher
Look at the proper assembly pictures from prusa I attached above - that would be incorrect assembly, as there should be a gap there to ensure the nozzle, when tightened, is bound only against the heat break and not bound against the heat block.
Failing to assemble in the way Prusa specifies can lead to filament oozing out of the spiral leakage path of the threads. The nozzle must be sealed against the heat break to prevent that.
Think of all the threads you’ve seen on this forum of people taking pictures of filament oozing out of the top and bottom of their hot ends, that’s what causes that.
Is that right, hmm.
My nozzles always seem to butt up to the block.
Perhaps I have something wrong going on there too then.
I havent had any leaking issues of any kind, but it certainly stops against the block.
Maybe I should look at turning it in some more so it doesnt.
There’s not a huge amount of pressure inside the heat block, and filament is very viscous.
But the proper assembly way guarantees it won’t leak. Improper assembly does not necessarily guarantee it will leak, of that makes sense.
uh oh, multiple people replying at the same time…this can’t be good.
It does.
I’m going to compare hotend assemblies when I get home to see if my current one seems different in that regard.
From the one I had that was leaking I believe that part of the seal is from bottoming out into the hot end. I think I had a build up and it didn’t seat all the way.
-S
Well, if the nozzle tip height doesn’t really matter, and the thread is supposed to bottom out on the heatbreak anyhow then i don’t see why the nozzle x would not work
Yeah, what you said about leaking past the threads.
-S
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My only worry would be when first calibrating having it dig in to the bed.
-S
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I think this is impossible if the probe is functioning properly. I know that sounds ridiculous because so many people have dug into the bed, but hear me out.
I tested the calibration cycle with a piece of aluminum foil and I was able to get it to trigger at like 100mm above the top of the bed as it was coming down.
I ended up “successfully” generating a mesh that was crazy based on my randomly triggering it at different heights using some foil.
I think manually jogging the machine slowly down to the bed and making sure the probe triggers before the nozzle digs into the bed will ensure it doesn’t dig into the print surface.
Well I guess I wasted everyone’s time with my over thinking and misunderstanding as usual
Regardless I enjoyed the conversation.
No, no, absolutely not.
If this was so obvious how are the hot ends being assembled at the factory and being shipped “improperly” assembled??
I also enjoyed the conversation, and now there’s one more person fighting the good fight, since people are increasingly getting interested in changing nozzles. We all need to make sure people ‘not in the know’ don’t end up ruining their toolheads by assembling wrong.
It’s surely not a black and white issue, and there’s probably multiple ways of ‘properly’ assembling a hot end. But there’s some obvious traps to avoid.
For what it’s worth, my hotends from Snapmaker were also shipped screwed with the shoulder flush against the heat block, and since I haven’t had any leaking I haven’t bothered to tighten anything. But if I do get some leaking I’ll turn the heat break in about 1/4 turn and re-tighten the nozzle.
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That’s true. As long as you watch the little sensor light while manually lowering it you’d be fine. Just don’t start auto calibration before that.
I think since they fixed firmware and whatever problem with sensor adjustment from factory, the only one’s I’ve seen have been user error.
-S
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