Humidity, Altitude and the e3d hotend

I am posting this in the hopes that it will help relieve e3d suffering...

I completed my RepRap Prusa i3 Rework build about two months ago. At first, it was printing fine, in fact, I think my first print was my best. But then my Wade extruder/J-Head started getting clogged and jamming. Being new to 3d printers, I thought it was my J-Head hotend, and, well, I wanted a better extruder, so I thought the Bowden and a all-metal e3d (clone) was the way to go. So, I ordered everything I needed off of ebay. A couple of weeks later, and my rebuild was competed. Disaster followed. It would print a few layers and then jam up - even worse than my Wade and J-Head combo. I struggled for several weeks, trying every slic3r option, but nothing seemed to help. Finally, I boosted my print speed up to the max my printer could handle. I started getting some prints, but with lots of blobs. Ya, it was printing, but the prints looked like shit. I blamed the seller of my e3d clone 1.75 mm print head. He did try and help, but was at a loss as to why I was having such difficulty, while others were having success. Although I was able to do some small prints, my longer prints always failed with a jam.

This bothered me too. Why was I having such difficulty getting this setup to work? From my earlier tests, it was clear that the filament "melt" was creeping up the heatbreak, working its way up into the cold end, and lodging itself into the interface between the PTFE and the metal. I could even see a little ridge imprinted onto the PLA when I pulled it out. This had to be the cause of my troubles, this PTFE/metal interface was too close to the hotend. So, I decided to try some experiments. The experiment that opened my eyes, after a few others, was taking a heatbreak, all by itself, and heating it with my soldering station air blower to about 190C. I then took a length of 1.75mm PLA and manually pushed it into the hotend, while holding the heatbreak with some pliers. What followed surprised me. The PLA melted, as expected, and then rapidly gushed back out at me in a "molten froth."

Obviously, this PLA “molten froth ooze” is my problem. It gushed out of the heatbreak very rapidly, obviously driven by a rapid gas expansion. Steam. Everything became clear. I live in the mountains, and this time of year, it is very humid. I have been leaving my PLA out, and it has been sucking up this moisture. Add to that my altitude of 5000ft, and you get rapid steam expansion at PLA printing temps. This steam pressure is forcing the melted PLA back up and into the cold end of my heatbreak, where it freezes in place, jamming my e3d clone print head. By the way, I don't think the “clone” part has anything to do with this issue.

It seems to me that the e3d hotend is particularly susceptible to this failure mode. High humidity, altitude and the e3d don't mix. I'm sure this was also the root cause of my J-Head failures. When my PLA was new, out of the box, it worked fine. But, over the weeks, it sucked up moisture, until it became un-printable.

Today I will be ordering some vacuum sealed bags and silica desiccant bags off of ebay. I'll also be baking my PLA to drive out the moisture. My research says that about 130F for 4 hours should do the trick. Your suggestions are welcome, as I hope I don't ruin my spool of PLA. I'll update here how this works for me.

I see lots of others here on this forum having similar troubles with the e3d jamming. I would be curious to find out if your PLA has sucked up moisture… Also, I don't see any posts here about the effects of altitude on 3d printing. It would seem to me that higher altitudes will exacerbate moisture and PLA expansion issues.

Two observations:

1. You are using an E3D clone, not a genuine one, so you can't expect it to perform as well.

2. Your experiment with the soldering iron suggests to me that you are unaware that you need to keep the top end of the heat break cool, by having a fan blowing cool air over the heatsink. Of course filament will come out of the top if you don't keep it cool.

I doubt that your problem has anything to do with humidity or altitude.

Edited 2 time(s). Last edit at 09/09/2015 09:45AM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
Two observations:

1. You are using an E3D clone, not a genuine one, so you can't expect it to perform as well.

2. Your experiment with the soldering iron suggests to me that you are unaware that you need to keep the top end of the heat break cool, by having a fan blowing cool air over the heatsink. Of course filament will come out of the top if you don't keep it cool.

I doubt that your problem has anything to do with humidity or altitude.

1. I did say it was a clone, but I see others on the forum with real e3ds having the same issues. Besides, if there is a difference, I want to understand what the difference is, and give that knowledge to others so that we can improve on the design. RepRap is Open Source you know.

2. I'm very aware that the top part is intended to be kept cool with a fan, and yes my fan is wired to be on continuously. But, I don't think it is normal for the PLA to spit back out at me with puffs of steam. That can't be good. I will try drying my PLA out and see if it makes a difference, and then we can all learn from the results, even if it results in failure.

Please don't take this wrong. I know most people are posting here because they want help, and I appreciate that you are here trying to help others. Thank you for that! And I will consider that it is likely some issue resulting from the hotend being a clone. But if there is something special about the e3d hotend, as an advocate for Open Source, we should try and understand what that difference is, so that the community is not relying completely on a commercial product. If we understand the issues, then we can all benefit from the improvements that are sure to follow.

Maybe I was wrong about humidity probably not being a factor. The puffs of steam suggest that your filament has absorbed moisture. I guess the steam could be pushing semi-molten filament back up the cold end, and it may be solidifying there. All-metal hot ends don't like a lot of retraction, and I think this is because of the risk of filament solidifying in the cold end of the metal heat break.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

There are a few obvious differences between the clones ( I have ) and the original.

The fins of the heatsink are different. The e3d has a wider bottom with shorter fins going to a narrow top with longer fins. ( Like a conical cylinder, but the outer diameter is constant )
The hotend itself is different. The original clamping mechanism provides a bigger contact area between heat element and heaterblock. Keeps the temp hysteresis low.

What I observed with my clones was: the heaterblock must not get in contact with the heatsink. There were no provisions to counter the heat barrier into the heatsink, so I added a M6 nut. Even the nut must not get in contact with the heaterblock. Then I made my own fan duct with cardboard between the heatsink and hotend. Now the temps on the cold end are low as can be.

-Olaf

I have a number of "E3DV6" hot-ends bought from AliExpress, but no original to compare with. There's a range of heat blocks, heat breaks, and heatsinks, so cloning is obviously a very inexact science.

I struggled with exactly the same issues as alienmike, but I'm only at 500ft altitude. What eventually got things working was using a heat break which included a PTFE liner... the all-metal versions always jammed up at some point or other. One issue I definitely proved with the all-metal hotend was that when the filament stopped extruding (e.g. during a move or direction change) or even slowed down too much, it jammed. I had the hot end connected to the printer, maintaining 190, and manually pushed PLA filament into it. So long as I kept the filament moving, it was fine. If I stopped pushing for a few seconds and pushed again, it jammed. There were also some issues with retraction that I never got to the bottom of, but it did seem that disabling retraction made it a little less flakey. I haven't identified any issues with moisture in the PLA, despite it being winter with high humidity. I do keep my PLA in a sealed plastic box with a dehumidifier.... this seems to keep it at about 40-50% humidity.

I agree that the heater block shouldn't touch the heatsink. But also, the nozzle should be screwed as far into the heater block as possible, and the heat break should also be hard against the nozzle, inside the heater block. I'd think an M6 nut would be counterproductive... it would just act as another way to conduct heat up into the heatbreak, but YMMV. The Diamond hotend includes a mica? heatshield between the nozzle and heatsinks, and I expect that would be a good thing in a single-filament situation too.

Thank you so much for your reply!

What you describe is EXACTLY what I am seeing. Always good to know there is someone else out there that is experiencing this. My heating block is seperated from the cooling fins, and the fins match the description of the previous poster as well. Other posters with real all-metal e3ds also seem to be experiencing this problem when using the Bowden extruder.

It is just as you describe. As long as the filament keeps moving, and at a high rate, it will not jam. I solved the retraction problem, just retract at least 5mm. Anything less is a problematic, as the melt ends up right in that PTFE seam. But, that posses problems of its own. With such a long retraction, on complicated parts, with lots of parimeters, you get lots of retractions, leaving the melt up in the hotend too long, and eventually freezing it into the cold end. Damned if you do, damned if you don't (retract that is). If I don't retract, the prints are so globby, they are unusable, and usually die anyway from the printhead hitting the globbing print, without a lot of z-lift as well.

I'm sure the e3d with PTFE liner all the way through it will work fine. But later, I want to print ABS and Nylon, so that is a no go for me. But I think I will order a j-head and e3d clone, without the all-metal, and try those out too. The real e3d is too pricey for me right now, and I am enjoying diagnosing this issue.

On another note, my experiments with all of this gave me an idea yesterday for a new type of extruder, that has all of the advantages of a Bowden extruder, but without the retraction issues (retraction to release the pressure of the filament inside the PTFE liner), and also eliminates the bearing behind the mk8 extruder gear as well! I can't wait to build it and try it out. It also keeps the weight down on the carriage by moving the stepper off to the frame, just like the bowden, but can be geared as well. So, you see, this adventure will pay off! As soon as I prototype and verify the concept, I will post plans. It really has the potential to be a huge improvement over the Wade and Bowden designs, by removing the filament pressure from the PTFE liner. This should also eliminate the need for more than .2 mm retraction, making the e3d much more viable.

In otherwords, the issue really isn't with the e3d or its clones; I see it as really being a Bowden issue - that increased pressure of the filament inside the PTFE, that you have to release with excessive retraction. I think if we eliminate this problem, then all of the e3d printhead issues (when using a Bowden) will largely disappear.

The guidance from E3D for their genuine V6 hot-end is that retraction should never be more than 4mm, as any more would bring the molten tip of the filament up into the cooler part of the heat-break. They recommend that it should normally be a lot less, dependant on the material being used.

More trouble-shooting information here.

Of course, this is for the genuine item, and may not be appropriate for the clones.

Edited 1 time(s). Last edit at 09/10/2015 09:00AM by David J.

@David_J
You're right about the e3d retraction, but with a Bowden tube you still have to retract more to compensate the filament compression. In my case with a 500mm long PTFE tube I had to add 4.5mm for PLA and even more for PETG.
Still haven´t found a good setup for Bowden and PTFE to eliminate blobs and strings completely.

@alienmike
There had been a few ideas about "remote stepper extruding" Before you invest time and money, see what others have done ( and what has found the way into the market )
My own idea failed badly from too much friction on the gear. A reduction gear and proper linear bearings would have added too much complicity and weight, too.

[forums.reprap.org]
-Olaf

I ended up using 8mm retraction with my genuine E3Dv6 and 600mm Bowden tube. At 6mm I still got blobs. Now I don't have any blobs at all, but I do have stringing, especially at the start of a print.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
alienmike
I'm sure the e3d with PTFE liner all the way through it will work fine. But later, I want to print ABS and Nylon, so that is a no go for me. But I think I will order a j-head and e3d clone, without the all-metal, and try those out too. The real e3d is too pricey for me right now, and I am enjoying diagnosing this issue.

Yes, I also want to eventually print ABS and other hotter things. I figure that when I get to that point, I'll revisit the whole issue with an all-metal hotend. And yes, the real E3D is too pricey for me too.

Quote

In otherwords, the issue really isn't with the e3d or its clones; I see it as really being a Bowden issue - that increased pressure of the filament inside the PTFE, that you have to release with excessive retraction. I think if we eliminate this problem, then all of the e3d printhead issues (when using a Bowden) will largely disappear.

I should have said... I have a direct-drive extruder, not Bowden.

Quote
David J
The guidance from E3D for their genuine V6 hot-end is that retraction should never be more than 4mm, as any more would bring the molten tip of the filament up into the cooler part of the heat-break. They recommend that it should normally be a lot less, dependant on the material being used.

More trouble-shooting information here.

Of course, this is for the genuine item, and may not be appropriate for the clones.

Yep, I knew that. But my experience is, anything over 2mm is jam territory. Anything under 5 mm, and I get bad blobbing.

Quote
o_lampe
@alienmike
There had been a few ideas about "remote stepper extruding" Before you invest time and money, see what others have done ( and what has found the way into the market )
My own idea failed badly from too much friction on the gear. A reduction gear and proper linear bearings would have added too much complicity and weight, too.

[forums.reprap.org]
-Olaf

Thank you Olaf. Yes, I had seen a design like this on thingiverse. But really, my idea is so much better and simplier! Aren't your own ideas always better ? Besides, I already ordered the parts. I'll post my results.

I use a genuine E3D v6 hotend, and I bought 5 spool of filaments 2 months ago, 4 opened, I switch them every now and then depends what I am printing, I have abs at 235c to 240c, pla 195c, PET 230c, only problem I ever had was caused by the extruder, not the hotend, I am now using infill 3d direct drive and have no issue whatsoever, I made the greg wade geared extruder with scew-in for 10mm bowden coupler, but not switching yet since its working well at 60mm/s print speed, would like to go higher but not really needed yet.

my humidity in the house sometimes is as high as 85%, all filaments are just kept in the cardboard box it came in, with the little pack of those silica gel in it.



this was printed with abs at 235c

Edited 1 time(s). Last edit at 09/13/2015 08:51AM by deaconfrost.

Reprap is open source, but e3d is not. Your stolen copied hot end made by children in China is in no way an e3d other than the way it looks. It sounds like humidity is the root of your problem, but it's compounded by loose tolerances and shoddy machining. With an e3d you would likely still experience problems, but they would present in a different manor like out the nozzle bursts of steam instead of up through the heat break, but please don't say it's an e3d design flaw, because you don't have an e3d, and you don't know.

In the defense of chinese kids I have to say most E3D knockoffs are actually of a good quality.
Well, that is if you consider finnished in china to be the same as coming out of a machine.
What I am trying to say is that apart from some flaws with the tolerances they can be good and cheap base especially if the damn thing is actuall a bit too tight like my ones were.
The cold end is usually not polished, same for the heatbreak, this can be fixed within 30minutes with a dremel and the right sandpaper on a spindle.
The heatbreak need to machined so that a bit of thread is missing where it enters the nozzle - otherwise you end up with a gap at the end of the thread.
In this gap filament collects and with time goes bad, black and once it comes loose will block the nozzle.
Especially during retactions this is a major issue.
Heater cartridge and sensor often need an entire new block as the holes are usually a bit too big.

So yes, the original has the price for a good reason but it is possible with a bit of elbow grease to get a knockoff working 100% better than how it was ordered.
Guess it comes down to budget and learning
People investing 250$ into a "high end 3D printer" usually refuse to pay the price for good hardware until they are finally fed up and move on to something that actually works.
Some, like me, do it by tinkering other people might just just some parts to save on a new kit to assemble.