Heat Creep with E3DV6

[DannyCrane]

I have been fighting my printer for the past couple of months. My filament keeps jamming in the hot end after 30min of printing or so. I have a Rostock Max V2 with a E3DV6, and it was printing great until my computer crashed and took all my slicer settings with it (simplify3D). Since then, I have been having a hard time keeping my printer reliable. I have gotten some good prints out of it since then, but not I seem to get jams more often that good prints.

I have replaced the nozzle and the heat break, thinking I might have damaged them when I was trying to clear some earlier jams. After I replaced those parts, I got it printing great with Matterhacker PLA, but I ran out and switched over to Matterhacker ABS. The ABS jammed after 30min or so. I disassembled my hotend and cleaned everything out, started a print, and the abs jammed again. So I cleaned out the ABS and put some new PLA that I ordered into my machine. It started out printing fine, and as I was fine tuning my slicer settings, it started to have trouble again. I started getting under extrusion and it is very hard to push by hand, so when I am printing, the extruder just grinds up filament.

I have been searching online everywhere, and it seems like I am having a problem with heat creep. The filament seems to be jamming in the heat break. It seems like the common solution to fix that is proper assembly and making sure the heat sink fan is working properly, and I have done both. I have also tried using canola oil, which did not seem to make much difference.

All of the parts on my hot end are official E3D parts. At this point, the only thing that is different is I am using a different thermal paste for the heat sink. I did not have any of the heat sink compound that came with my hot end, so I used some arctic silver 5 instead. I checked the info on the paste and found this on their website:

Extended Temperature Limits:
Peak: –50°C to >180°C
Long-Term: –50°C to 130°C

Is this part of my problem? If so, what kind of thermal paste should I get instead? I was using the arctic silver before my computer crash, and it was working fine before with ABS and PLA. Even after I lost all my settings, I was able to get some good prints off of it, but I just can't seem to keep it reliable.

Any other thoughts? I have tried every fix I could find online with no success. It has been more than 3 months of this and I am running out of ideas.

[mhackney]

Safe money is that your retract setting in the slicer is too large. This could have happened when you lost all your slicer settings. So now, you are retracting filament up into the heat break - the kiss of death for any hot end.

And often, you can get "some good prints" with very poor slicer settings. Some of this has to do with the part geometry itself, some are just easier to print (less retracts for instance) than others.

[Mac The Knife]

Retraction settings?

[DannyCrane]

I have been experimenting with that. My last setting were :

Retraction : 4mm
Extra Restart distance: 0mm
Retraction Vertical Lift: 2.6mm
Retraction Speed: 25mm/s
Coasting distance: 3mm
Wipe Distance: 2mm

These were the settings that I was using to get some good prints with my older roll of PLA. I started out with no retraction, and had huge blobs on the outer layer of the prints, with lots of stringing. With the settings above, I got rid of the blobs, minimal stringing, and good bridging. I have been using the 3D benchy model for my testing. As for temps, I was at 192c for the PLA. Any hotter or colder and the filament started to get harder to push out.

I have attached some pictures of the last successful model I printed with those settings and the older PLA that I had.

[img]http://i.imgur.com/86KVF9w.jpg[/img]

[img]http://i.imgur.com/e3y7bFr.jpg[/img]

[img]http://i.imgur.com/Ghr43WV.jpg[/img]

[img]http://i.imgur.com/Z67mJAo.jpg[/img]

[img]http://i.imgur.com/v4TG9FL.jpg[/img]

[mhackney]

And there you have it, 4mm is WAY too high for retract on an E3D full metal hot end. I use 1.5mm but you can go up to 2mm.

The forums and web are filled with people who set their E3D retracts above 2mm and claim "success". I can guarantee that they are in denial and a problem will occur and they'll have no idea why or how to solve. I've measured, studied, experimented and consulted on this. E3D give me credit on their blog for my work and input to the V6 nozzle design. As I said above, "yes" it is possible to have a good print with overly high retract settings. It is all a matter of statistics whether you do or not. Long prints, rapid vs slower print speeds, lots of retracts and many other geometry and slicer parameters affect how long and if the melt makes it up into the transition zone. At some point it will, maybe even for a second or two. Read this for more info: http://sublimelayers.blogspot.com/2016/ ... racts.html

[DannyCrane]

I got to 4mm retract distance by repeatedly printing the 3dbenchy, starting with no retraction, and slowly building up from there. I found the lower retract distance left me with a ton of strings and big blobs on the outer layer. Are there ways to minimize those problems while keeping my printer reliable? On a side note, I have a 0.4 mm nozzle, and I was printing at 50mm/s before reliably, but after the problems I slowed it down 35mm/s and still having issues, both stringing and not extruding.

Thank you for the links, defiantly better information than I have been able to find relating to my problem. I will certainly try everything on there, but it will have to wait till I get off work before I can try them.

[mhackney]

Yes there are ways of dealing with the stinging. You have to look at EVERYTHING in total and not rely on a single factor to be the magic fix. Some factors like retract have practical limits. Some slicers have better strategies (i.e. KISSslicer) than others (i.e. S3D) for dealing with things like this.

The first place to start is go slow - 35mm/s as you've done. Then profile the temperature to find the lowest printable temperature for your PLA. Then use that pus 5°C as your standard temp. Next, set retract to 1.5mm at 15-20mm/s. If you have KISS you can speed up the advance to 35mm/s.

I won't (be able to) help with S3D slicing issues, there are parameters that might help like coast/wipe, etc. I like to use a 4mm Z lift. Also, read the guides linked in my signature.

[IMBoring25]

Coast/wipe or as other slicers may call a similar concept, pressure advance, can minimize the actual retraction required.

[DeltaCon]

Then profile the temperature to find the lowest printable temperature for your PLA. Then use that pus 5°C as your standard temp. Next, set retract to 1.5mm at 15-20mm/s. If you have KISS you can speed up the advance to 35mm/s.

Yes, I think I read that before on your blog. But do you mean the lowest printable temp, the temp where the filament is just not skipping in the extruder? That highly depends on which extruder you have. Is it true that if you use a bondtech (e.g.) that you can print at lower temps because it pushes harder? And that if you want to print faster, you will need to up the temp a bit again and take the stringing for granted? Do you recommend to use the wipe feature som slicers (incl KISS) offer? Sometimes I get the feeling it only makes the strings more difficult to remove.

[mhackney]

Yes, the lowest printable temp and then add 5°C for a little buffer. And yes, you do this for your system - extruder, PTFE dimensions, part cooling, etc. It all plays together.

In general it is not a good idea to use excess pressure (cold melt) to fix problems. It results in others. So I print at reasonable melt temps. What you are trying to do is get in a good region and not use too much heat. Faster printing is more challenging. You do usually need to increase temp as you speed up but this is where experience and required results come into play. I do use wipe, .5mm.

Here is a platter of parts I just printed. I have not touched any part and as you can see, no stringing whatsoever. Those thin pillars are very challenging as are the parts with the open weave and the "gear" looking part.

[DannyCrane]

Thank you for the advice, it has helped quite a bit. After reading through your guides, I lowered my retraction to 2mm, got rid of my coasting settings, and have a small wipe move around 1mm. I also sped up my travel movement for non printing moves, which also seemed to help. I have almost printed through an entire roll of PLA, and the prints I am getting are some of the best I have gotten out of my printer.

I am still having a small issue with stringing however. When I print a set of parts similar to the fishing reel that you posted, I get these super fine strings coming off the parts. My first instinct would be to raise the retraction setting some more, but I was afraid of jamming again. Are there any other settings you might suggest to help with that? I know I can't lower my temp anymore. When I did that, the layers would no longer have the strength they need to stay together.

Also, I am printing at 35mm/s, and I would like to raise the speed to 50 mm/s. How much do you usually raise the temp when increasing the speed? In my example, I found that 205c was the magic temp at 35 mm/s that gave me good strength. Should I raise the temp when I bump up the speed to 50?