Another E3D V6 Jamming

Hi all, I'm at my wits end and finally turning to the forums for help. I have recently installed a new genuine E3D V6 hotend (following all official instructions) with bowden. It printed fine for a week until I decided to change filament. All of a sudden it wouldn't print anymore. I tried multiple different filaments including the one that had previously printed fine. I completely disassembled the hotend and reassembled it per E3D instructions. I used thermal grease on the heat break before screwing into the heat sink. I did a hot tighten of the nozzle after assembly. I completely cleaned out the nozzle and heat break. I made sure to cut a perfect 90 angle on the PTFE tube and insert it all the way into the heat break. The fan is always on at 100% and the heat sink shroud is covering all of the fins of the heat sink.
The prints seem to start ok for maybe a minute, but then I stop getting any filament out and I can see the extruder is skipping. I finally attempted some cold pulls to investigate and this is when I think I found the culprit. I pulled once with the PTFE tube in and once without, but both had the same results. It appeared that near the end of where the heat break would be that the filament had expanded very slightly (to a little over 2mm according to my calipers). It seems to me that this 2mm expansion must be causing a jam and the filament can no longer go through. If this is truly the issue I'm not exactly sure how to fix it since, like I said, my fan is on 100% and covering the entire heat sink and I do have thermal grease between heat break and heat sink. So this is where I need ideas, has anyone else experienced jamming due to a small amount of filament expansion in the heat break? I am attaching a picture of the cold pulled filament so you can see what I'm talking about. Thanks for any help you can provide!

~mindseye1~

There are a lot of historic posts in a similar vain.
Tends to be a bigger issue with PLA and/or bowden systems. The bowden uses a larger retract distance and the filament cools in the bowden.
If its the same issue you may want to reduce your hot end temperature to the lower end of the range and try reducing the retraction distance. Obviously less retraction gives other issues.

I am running my hot end at 190 degC. Also, in the picture you can see that examples of both with and without the PTFE tube produce the same results, so it doesn't appear to be a bowden issue. Lastly, this happens even when I am extracting straight through during testing (e.g. extract 50mm, no retraction).

I would suggest you have a bad or misaligned heat brake.

There are several types of these heads, all metal heat brake, the type with the small ptfe tube in it, and the type that has the feed tube to all the way down thru the heat brake to the nozzle.

With PLA you can use the PTFE types, but with higher temp filaments like PETG or ABS you should use the all metal setup.

Extraction should not exceed 5mm just for reference, also your heat brake cooling fan (not the print fan) should be always on when the hot end is above 50c and supply at the very least 4 cfm of air.

If your heat brake is designed for PTFE you will get jams if you dont use it right, like every time!
The PTFE tube MUST press up against the brass nozzle and be aligned well. If there is gap at the nozzle you will get molten filament build up and jam.

This is the standard all-metal heat brake included with the E3D V6. I am inserting a bowden PTFE tube into the top end of it as far as I can push it. It for sure does not go all the way to the nozzle though because there is a narrow section before the screw that goes into the heater block that the PTFE will not fit through. I've ordered a couple extra heat brakes from Amazon to try and see if that is the issue, but honestly it looks pretty straight to me so I'm not confident that will fix it.

Edited 1 time(s). Last edit at 01/29/2018 12:34PM by mindseye1.

Sorry I took a closer look at your picture in your first post, somehow you must be getting heat migration up into your heat brake.

I ask this just to be clear, you stated that your heat brake fan is on at 100% but in most configurations there is no adjusting that...
Its just on and connected directly to 12v (or24v if that's your setup)
So just encase we are misunderstanding when you say 100% are you referring to your print fan? As that is an adjustable via M106 speed controlled fan...

I am wondering if there may be some airflow issues on your head setup... Thus I would like to see pics of that plz.
Plz post some pics of your assembly as it is setup when your printing, each side plz.

Yes I did actually mean the 12V fan. I only said 100% to make it clear it was on at all times when the RAMPS board was powered. I'm not sure how to measure the CFM, but it seems pretty powerful for such a tiny fan. It is blowing air outward from the heat sink, not towards it. Also, when I set the hot end to 200 degC I can touch the bottom fin of the heat sink and it is still cool to the touch. I am attaching a few more pics of the hot end. I really appreciate you taking a look at this, I'm just not sure what to try next (other than trying out the new heat breaks when they arrive, but I'll be surprised if the work better than a real E3D).

Are you sure you have that right? it should be blowing air ONTO the heat sink not away.
If that fan was supplied by E3d and its orig as supplied I would be confident in it being over 4 cfm likely over 5...
Some of the clone v6 hotends are supplied with too small of fans...
From the pics btw that is how I believe you have it mounted... blowing onto... all fans I have seen blow towards the label side.

Hmm, I have mine mounted so that it blows sideways, pulling in air from left and blowing across the heat sink out to a clear vent area on the opposite side...
My print fan is mounted in front... Not that it should be needed to do that tho... as long as the air is not restricted from escaping in behind the heat sink...

Your printer looks similar to my hyper cube Evo build I am working on now
I am not sure whats allowing the heat to come up the heat brake but that has to be it....

Mine is all metal setup, tho I have not used PLA with it much. Thats going to change next week tho... I have a lot of printing to do for a cosplay costume and PETG is pretty slow to print..

I wonder, if the heat sink compound you used is somehow doing the opposite of what its intended to do..... Insulating the heat from transfer into the heat sink...
There are thermal pastes designed to not allow heat to transfer... That would clearly be the opposite effect your after, and they are not very common...

Edited 1 time(s). Last edit at 01/29/2018 05:43PM by JustSumGuy.

You never said how much retraction you're using. If the retraction is excessive, you can pull soft/molten filament into the heatbreak where it will quickly cool and stick. What kind of motor are you using? Some people like to use pancake motors on Titan extruders to make a light weight extruder. They rely on the torque multiplication of the gears to get the push needed to move the filament. 3x almost zero= almost zero. I prefer larger motors that have pretty good torque to start with which then gets multiplied and provides a lot of push. If there's insufficient torque to push the filament when it starts getting stuck in the heatbreak, successive retractions may pull it further up and lead to a complete jam. Do you have a geared extruder?

When you put the teflon tube down into the heatsink/heatbreak you lock it in by lifting up on the black lock ring at the top of the heatsink while holding the telfon tube against the bottom of the heatbreak. If you don't push the tube down while you lift the lock ring, the tube can pull up a few mm and lift with the lock ring. That will leave a gap between the heatbreak and the bottom of the teflon tube, a perfect space for soft plastic to harden into a lump that can't possibly fit through the heatbreak. Soft plastic should never get that far (see comment above), but if it does, you're screwed.

It shouldn't matter if the fan is sucking or blowing on the heatsink. It will move the same amount air either way.

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I am using 4mm of retraction during a print. But this actually happens during testing though when I am just extruding straight through with no retraction. I set it to extrude about 50mm and it will start skipping during this. The printer is an Anet A8 so I'm using the motor and extruder from that. It has a toothed gear and an idler that push the filament so I don't think this is a "geared" extruder.
Also, yes I am making sure there is NO play in the teflon tube after insertion, and I also use the included lock ring.
I was mistaken about the fan direction. I just verified and it is definitely blowing onto the heat sink, not sucking air from the heat sink, so I think I'm ok there. And lastly, I used the thermal grease included with the E3D, and it is simply labeled "HEATSINK COMPOUND".

If it jams without retraction, there are a limited number of possibilities:
the nozzle is blocked- clean it out
the motor torque is too low - check the current and the cable/connector(s)
the motor driver is busted- swap with another to check
the drive gear is slipping on the motor shaft- apply some lock-tite and tighten the screw
the drive gear is chewing a divot into the filament - increase the pinch roller pressure
the temperature is too low- turn it up (are you sure the filament is PLA and not ABS?)
there's a problem with the filament-diameter poorly controlled and too big- use different filament
filament not feeding from the spool- free it up
trying to extrude too fast- how are you telling it to extrude 50mm of filament?

---

Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

So I'm starting to think there are separate issues at play here and maybe that is why it is such a confusing issue. The jamming during a print seems to be due to too much retraction. The jamming during straight extraction however is not actually jamming but just the filament needing a LOT of force to push through. I tried to do this manually and I was getting extrusion but I had to push VERY hard. Harder I imagine than what my extruder can handle, and so it was skipping. So on this note I tried a test print with a higher heat (210 degC) and a lower retraction (1.5 mm) and I was able to produce the attached print. I still think there are some extrusion issues, but I'm not completely shutdown like I thought I was. I'm going to look into getting a better extruder gear and possibly one of the mentioned geared extruders and see if it fares any better.

Edited 1 time(s). Last edit at 01/29/2018 10:41PM by mindseye1.

hmm, ok, perhaps you should look at upping the driver vref on your extruder....

DD has outlined pretty much all the stuff, tho I am still drawn back to the pic on your first post that shows filament being affected by heat up in the heat brake.....

Can you turn the hot end 90 degrees so the fan is blowing along the X axis?
Looks like you are trying to blow the air into the X cariage. Thats going to restrict the flow.