"MMU" Heat Break
Just because I'm lost on the topic, and so are others I talk to.
The heat break I just ordered, a "red stripe" came without a red stripe. I'm trying to figure out what I got, and to see if it is different from what I got with the mk3 in May 2018.
The one I got looks like it is 2.0 mm ID until the bit which is in the heat break, then it shrinks to 1.95 mm (I was able to fit in a 5/64" and #47 drill bit, respectively. )
I'll update later when I get the stock one off. I have gotten a picture from Support, but no dimensions.
I maintain an informal list of San Diego, CA 3D printing enthusiasts. PM me for details. If you include a contact email and I can add you to the informal mailing list.
Re: "MMU" Heat Break
All heat breaks shipped with Mk3 are the modified type. A 4mm hole for the PTFE, reducing to 2.1mm and then 2mm drilled from the lower end.
Unfortunately, the lower hole is not always exactly concentric with the upper hole and it is possible that you may have a slight ledge where the two meet.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: "MMU" Heat Break
I swear the other day I noticed both in the eshop, now I only see the mmu one.
I have a Prusa,therefore I research.
Re: "MMU" Heat Break
I have a standard e3d installed currently (replaced my original MK3 hot end a few months back after a jam) and two new ones on order that are MK3 specific. One from e3d and the other from Prusa. I’ll report back with an update.
Re: "MMU" Heat Break
Received my replacement heat brakes from Prusa and it was as you described. The transition from 2 to 2.1 mm is at the hot end of the narrow section. I was having a lot of problems with MMU2 prints as the heat brake I had in the extruder had the transition from 2 to 2.1 at the cold end of the narrow section so a slightly wide filament would get stuck there and not melt. My Prusa replacements don't have the red ring at the transition either. But they are sure working well.
Re: "MMU" Heat Break
I was not able to get a 2.0 drill bit, itself slightly undersized, through the heat break, suggesting it's 1.9.
Either way, it has the step you describe (looks reasonably centered though I could see how it might not be sometimes).
Mostly I just don't want to take it apart when it's working great to swap in the same exact part. For that matter, I wish I'd bought filament instead of a heat break just like the one I already have, if that's the case.
Mine were dirty just like the picture. I spent a while cleaning it.
I maintain an informal list of San Diego, CA 3D printing enthusiasts. PM me for details. If you include a contact email and I can add you to the informal mailing list.
Re: "MMU" Heat Break
Abraham
When I first had the MMU1, with the original heat break and 2.0 mm holes from both top and bottom, I used the flutes of a 1.8 mm drill bit to polish the inside, which really helped a lot in smoothing out the step.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: "MMU" Heat Break
I received a drawing from Prusa which is not of what I have, along with the statement that even the MK2's ship with the same heat break.
So there's:
1) Red one on the website - rumoured to have a step
2) The thing I was mailed when I ordered #1. It has no stripe, and an internal step.
3) The thing that came in my 05/2018 Mk3, no stripe, unknown step status
4) Perhaps the mk2's used to come with a different throat?
It's all pretty confusing and multiple weeks asking support and on the forums hasn't gotten a lot of reliable answers.
Step in my newly ordered heatbreak:
I maintain an informal list of San Diego, CA 3D printing enthusiasts. PM me for details. If you include a contact email and I can add you to the informal mailing list.
Re: "MMU" Heat Break
I have not had mine a part so I couldn't look at it for you. but the MMU2 seems to work even without the new PTFE tubing. small chance I will have to swap them out. and if I do I will look at mine.
I have a Prusa,therefore I research.
Re: "MMU" Heat Break
I received a drawing from Prusa which is not of what I have, along with the statement that even the MK2's ship with the same heat break.
So there's:
1) Red one on the website - rumoured to have a step
2) The thing I was mailed when I ordered #1. It has no stripe, and an internal step.
3) The thing that came in my 05/2018 Mk3, no stripe, unknown step status
4) Perhaps the mk2's used to come with a different throat?
It's all pretty confusing and multiple weeks asking support and on the forums hasn't gotten a lot of reliable answers.
Step in my newly ordered heatbreak:
The drawing you have is the stock E3D heat break. Unfortunately, all these heat breaks have some sort of step; the 2mm hole is drilled from both ends and the vast majority of those holes do not meet exactly in the middle.
Early Mk2 printers were indeed shipped with the stock heat break. When MMU1 was in development, it was realised that the step in those was causing issues with the unloading, so PR staff went to E3D to find a solution and that was the 2.1mm hole from the top.
PR received a batch of these and shipped them with the MMU1 (assembled as complete replacement extruders) and once stocks of the standard heat break ran out, they started shipping with the Mk2. Initially they had a marking which was later phased out.
Being involved with the early MMU1 beta, and not experiencing the unload issues that others did, I realised that it was because I had previously drilled out some stuck filament with a 1.8 mm drill bit and at the same time, I had polished the inner bore with the flutes, removing much of the existing step.
I tested this theory with a second printer and the original heat break and ended up with no issues again.
Anyway, to the best of my knowledge, from that time, all heat breaks shipped by PR have the 2.1mm hole from the top.
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: "MMU" Heat Break
Hello everybody,
I confirm that what Peter wrote here above my comment is correct. Don't be confused by the red stripe.
Martin L.
Official Prusa Research CS
Re: "MMU" Heat Break
YAY!!! It seems that I got something right (at last) 😀
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: "MMU" Heat Break
YAY!!! It seems that I got something right (at last) 😀
To some this is the season of miracles. 😈
Re: "MMU" Heat Break
YAY!!! It seems that I got something right (at last) 😀
To some this is the season of miracles. 😈
😀 😀 😀
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: "MMU" Heat Break
Much of that makes sense.
But the step is pretty big? It's not a misallignment, because the ring is well centered in the hole and uniform.
It's just about at the top of the heater-block (at end of thinned threadless section.
1.96 mm fits, 2.048 does not, so yeah, looks like a 2.0 hole at the bottom. A Number 44 (2.184mm) bit goes in, so it's about 2.2 mm in the majority of the tube. Not to split hairs, but it is NOT 2.1 mm at the top.
From what you're saying: Do you feel the necked down tube is the way to go? Do you think that end should get chamfered down a bit instead of being a 0.1mm step all the way around?
How will having that step improve things relative to the earlier, straight through design?
This is what I have, as best I can measure.
I maintain an informal list of San Diego, CA 3D printing enthusiasts. PM me for details. If you include a contact email and I can add you to the informal mailing list.
Re: "MMU" Heat Break
Just to finish the thread: I got a NEW replacement heat break from Prusa - they wanted to make sure I had the "right" one.
It does have the same step in the same place as the other. It is NOT a misalignment, it is significantly stepped down at the tip and seems to be aligned very well.
I'm unsure why they have a drawing that is of something other than what they send, and I offered to provide one, but it seems like it's relagated to tribal knowledge: If you ask Prusa what the heat break is, it is NOT what they tell you and is instead what I drew above.
It seems to work well for people, so it's not a problem, it's just not what they say. I'm putting together a Skelestruder https://www.thingiverse.com/thing:2845416 and will compare the old heat break (that shipped in May 2018) when I get it out.
I maintain an informal list of San Diego, CA 3D printing enthusiasts. PM me for details. If you include a contact email and I can add you to the informal mailing list.
RE: "MMU" Heat Break
Old thread, but I was digging into this once again because a was tempted to order E3D's titanium heatbreak and I managed to find archived drawing of the modified heatbreak from E3D. So for future me and in case enyone else stumbles upon this thread I am uploading it here. PRUSA-BREAK-175-(Edition-1)