Help please with E3d v6 clone jam symptoms

Looking for help diagnosing what's happening here. It's a new prusa i3 setup, ebay clone e3d v6, with a bowden extruder. 1.75mm, measured ok.

I've tried temps ranging anywhere between 180 and 230, with the same result. I can get a nice flow by hand when I first load the filament, but then flow is weak (curling as it comes out) and then stops altogether when using yhe extruder.

I suspect the ptfe tube is not fully inserted, so I intend to work on that. I've cleaned the nozzle (0.3) and heat break a few times already with same result. Fan is working fine afaik, and the heat sink is warm to touch, but not hot. Next test will be without the nozzle installed, as I read elsewhere in the forums.

Help would be appreciated. I'm so close to having a working machine.

Thanks in advance,
Kfj

Wow, I've never seen a profile like that, and I can't imagine how it was formed. Can you estimate where in the hotend the various parts of that photo lined up? I think I can be fairly confident that the cloned parts you have are not to spec and are unlikely to ever work.

That's a good question, I think it's somewhere in the heat break. I'll check it this morning. As I said, I suspect if the ptfe tube is not all the way down the throat of the heat break, there will be a small gap where the filament can melt enough to create that small collar and thus jam.

As I read more, I gather a warm heat sink is not good. It's only mildly warm to the touch, but maybe that's enough.

Thanks for your reply.

The filament path should be bigger than the filament all the way to and including the first part of the nozzle. Once you get into the nozzle the filament path should only get smaller, typically in two steps, the first of which is very short. So that long narrow section, followed by a swollen section is extremely unusual. If the swollen section is the joint between the throat and the nozzle, then the long narrow section would have to be in the throat, and that rates as just plain wrong. If you disassemble the hotend and can see a narrow section in the lower part of the throat then you should probably order a replacement with a more conventional profile. You could also try drilling out the throat so that there's a 2mm bore, but it would probably be a good idea to have a spare first. Some manufacturers make the narrowed section of the heatbreak/throat very thin, so modifications can be risky.

I think you may be looking at the ptfe tubing. The filament is normal right up to the bulge.

Well, that makes a lot more sense!

Ok, in that case we just need to figure out what space the filament is expanding into at the bulge and get rid of it. A gap between the end of the ptfe liner and the bottom of the wide bore in the throat is a possibility. Sometimes you need to shape the end of the ptfe to match the slope of the bottom of the bore to get a good fit. Another possibility is the join between the nozzle and the end of the throat, but if you had that much gap there I'd expect the hotend to leak plastic.

Yes, you hava a gap between the heat brake pipe and nozzle. Replace the inner PTFE tube to the correct length or replace it with a full metal one.

Ggherbaz, Thanks for your comment. Between the heat break and the nozzle, shouldn't the plastic be sufficiently molten to continue to flow? And re the remark about ptfe tube length vs a full metal one, does that apply to a bowden setup? I'm probably not catching your drift.

It doesn't matter if bowden or not, there is two types of heat brakes, the ones with PTFE tube and the ones that are all metal, this ones the bowden tube only reach the top and never gets down to the nozzle, will have some issues once in a while with PLA but will allow you to print with more filaments.

The problem with the gap is that the filament glue itself to the metal and works as a brake creating a lot of friction slowing the flow of filament and allowing the heated and expanded filament to reach the cold end of the hotend and creating the jam.

Ok, well a few light bulbs are going off. Thanks to your replies, I was starting to suspect something was wrong with my heat break.

See File_1.jpg. The hole where the ptfe tube slides in is roughly 14.5 mm deep.

When I look at the e3d website (File_2.jpg) , the cross-sections they show for their heat breaks aren't that deep at all.

Because mine is so deep, it's maybe too close to the hot end (File_3.jpg) where the filament has a chance to get squishy and fill whatever gap there may be between the end of the ptfe tube and the end of the heat break.

I think that's what I'm seeing. Why would they ship a heat break design so different from the standard? Is there some other version?

I guess I won't know for sure this is it until I get some replacements and try them out.

Thanks to everyone for helping. I'll let you know how I make out.

Ken

Yes, exactly. My clone e3d style throats have the same mistake - it's the worst possible place for the ptfe to end. You can make it work, but you have really get a good fit on the ptfe tube. Mine are non-bowden, so I have a short piece of ptfe that is held captive by an upper aluminum mount. It might be difficult to get the bowden tube under enough pressure to keep it tight against the end of the bore with a normal push-type connector.

Quote
Kfj
Why would they ship a heat break design so different from the standard?

Because people will pay for them.

I'm quite convinced that the really cheap Chinese (aka eBay) stuff is actually rejects from the QA process of the good products, retrieved from garbage bins by "entrepreneurs" and sold off to other entrepreneurs without any technical knowledge whose only skill is in selling. The business model is that only a few customers will figure out that the goods are no good... pay refunds to them, and profit off the rest. If/when the profit drops too much, move on to another product (pure virgin Brazilian hair pieces seem quite popular at the moment).

The tricky thing is that paying more for an E3D v6 "clone" is still no guarantee that you'll get a good one.

Maybe a cheap option is to get a heatbreak and nozzle from E3D? If they will fit

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Prusa i3 upgraded with some of my own parts and E3D v6 hardened steel nozzle, large 400mm3 enclosed printer in to revision 3

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