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Unresolved Filament stuck.

Discussion in 'Troubleshooting' started by joea, Nov 2, 2020.

  1. joea

    joea Active Member

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    That makes more sense that my rushed conclusion. Certainly more current for the heater than for a signal wire.
     
  2. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Work with them enough and you can do it in your sleep :)
    The hotends are not super complex or complicated, but if you haven't assembled or disassembled one it is new territory.
     
  3. joea

    joea Active Member

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    I am unable to determine what this is. It resembles earlier versions of the E3D, v3 or v4, but who knows? I was able to remove the heater capsule, Seems to be just a "friction fit" without any clamping screws. The hole for the thermistor, once cleaned out, goes all the way through.,

    In any case, pretty much decided on going to a current version of the E3dv6. The cooling fins of the current one are 1 inch diameter, which suggest I can use the current snap on cooling fan, but I remain uncertain as to the mounting. From the installation thread, I gather I have the "older style" with the two mounting screws and thus have nothing to print out before hand and should be "golden", or at least sliver, maybe bronze, in that it should be almost plug and play, as far as the physical install and electrical hookup goes.

    I guess I still have to determine 12v vs 24v. Simplest thing is to snip the heater wires, power on and attempt to power the heater?
     

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  4. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    The heater core should have a small allen screw that comes in from one side or the other and pressure clamps against the heater core to hold it in place. However, ... Once you get that plastic all over the place down there it is possible some melted plastic is entrained on the heater core and helping to hold it in. Make sure there is no screw coming in from one side or another that is holding it first. There usually is.
     
  5. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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  6. mark tomlinson

    mark tomlinson ༼ つ ◕_ ◕ ༽つ
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    Since it is a small screw it is entirely possible some of the plastic gunked up on the heater block is hiding it for you
     
  7. Rod Smith

    Rod Smith Member

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    Based on your photos, that looks like an E3D V5 -- it has ten full-sized cooling fins (vs. 11 on the V6), plus one smaller one at the top. (See E3D's V6 description, including photos and a comparison to the V5.) The fins are thinner than on the V4. At this point in time, there's not much point in going with another V5, unless perhaps your specific mounting configuration would need to be modified to accommodate a V6. There are precise dimensions available online, but I don't happen to have a link. I do know that the V5 is taller than the V6, so if you switch to a V6, you may need to change out your part cooling fan duct (if you have one), since a duct designed for the V5 will be too low for use with a V6.

    AFAIK, all Robo3D R1-series printers used Hexagon hotends originally. (I know relatively little about the non-Plus R1 and pre-production units, though.) The Hexagon is even smaller than the E3D V6; here's a comparison:

    [​IMG]
    Your printer, though, has obviously been modified for (or is a prototype designed for) an E3D V5, so switching over to a Hexagon would likely be at least as much work as switching to an E3D V6.

    Chinese clones are kind of hit-or-miss. If you buy a generic clone on eBay or the like, you will indeed be rolling the dice. What you get may work fine or may be complete junk. Lots of people use such clones fine, but some people become frustrated with their clones. If you go for a clone, I recommend you research brands and get one that's not generic. Triangle Labs and Phaetus both have decent reputations, from what I've heard; but getting a genuine E3D product is definitely the safest approach. Also note that the genuine E3D V6 is an "all-metal" design, whereas many clones have a piece of PTFE tubing that goes down well into the heater block. This limits the temperature at which you can print to about 240C or 250C, so even printing PETG can be iffy with them. (The Hexagon is another all-metal design.) I definitely recommend an all-metal hotend, although PTFE-lined ones can make jams when printing PLA a little less likely unless the maching is very good in the all-metal design. (That's part of why genuine E3D products cost more; you're paying for quality machining.)

    Note that recent production, especially from the non-generic brands (E3D, TL, Phaetus, and likely others) uses a cartridge-style thermistor (like the heater cartridge, but smaller), rather than a bead-style thermistor, which is what you seem to have. The cartridge-style thermistors are easier to manage and secure.

    In the last three years or so, there have been developments in hotends that may be worth considering. Many of these use more advanced (and therefore more expensive) metals for superior thermal properties, which means they can print at higher temperatures and (at least theoretically) perform better even with more mundane plastics like PLA. (Printing these high-temperature plastics would likely require a 50W heater cartridge and a high-temperature thermistor of PT1000 probe, which in turn will require firmware changes, so you might not want to go there, at least not immediately.) Some products you might want to consider include:
    • Slice Engineering Mosquito -- This is the most radical of the recent designs, and it will almost certainly require that you upgrade your whole carriage design. It has a lot of advantages, at least on paper, including easier nozzle swaps and the aforementioned better thermal properties. Genuine products are expensive, though; and I don't know offhand if there are carriage designs on Thingiverse to accommodate this hotend with the Robo R1-series printers.
    • Slice Engineering Copperhead -- This product takes many of the features of the Mosquito and puts it in a modular package that's more compatible with E3D V6 carriages, etc. I've got one of these on a Kossel XL, paired with what is essentially a V6 heat sink. (I don't know if it would work with your existing V5 heat sink.) Thus, you might be able to use one of these with your existing carriage. They're less expensive than the Mosquito, but more expensive than a genuine E3D V6.
    • Dragon (variants available from Phaetus and Triangle Labs) -- This design takes some of the Mosquito's best features but packages it in a way that makes them optimally compatible with the E3D V6. Thus, you can swap out a V6 for a Dragon with minimal fuss. They're also much less expensive than a Mosquito, or even a Copperhead, but still a bit pricier than a V6. I've got a Phaetus Dragon in a SecKit SK-Go2 CoreXY printer that I've just built, and so far it's doing well. I have yet to try printing any high-temperature filaments with it, though (that's one of the reasons I bought it rather than using a V6).
    • Phaetus Dragonfly -- This is to the Dragon what the Copperhead is to the Mosquito -- a more conventional mounting design paired with multi-metal design.
    • E3D Hemera -- This is a combination of hotend and extruder, which makes for a more compact and lightweight package compared to one in which these components are separate. You'd almost certainly need to modify your carriage, though. I don't believe it uses any advanced materials, so you might not be able to print the more exotic high-temperature plastics with it.
    See this YouTube video for a comparison of the V6, Dragon, and Mosquito. All of these use compatible heater cores, thermistors, and nozzles. Some typically come with these items, but increasingly they're being de-bundled, so be sure you know what you're getting. (You can probably use your existing heater core, and I think (but am not positive) also the V5 nozzle you've got, but not the thermistor, since yours is bead-style, whereas the above all use cartridge-style.)

    There are others, too, including hotends that take two or three filament inputs with one output for multi-material processing. Many of the above have high-flow variants (like the E3D Volcano hotend), which are most useful in conjunction with nozzles with bigger diameters than the 0.4mm that's typical. These are great for printing big parts that don't require fine detail, but not so good if you want to print with fine detail.

    Given your needs, I'd recommend you look seriously at a Dragon or Copperhead hotend, unless you discover that your mount is so tied to the V5 that it would be a hassle to upgrade from that. If budget is more of a concern, then a TL or Phaetus V6 clone may be a good choice.

    All that said, though, your current hotend is likely salvageable. I don't happen to have any URLs on hand, but there are plenty of online tutorials and YouTube videos about hotend maintenance. Cleaning the built-up plastic goop off your hotend isn't all that hard, although if it's clogged up the inside, that can be more of a challenge. (Products to help clean up such clogs exist; see, for instance, this Amazon listing -- although that's just one example product.) The real danger is that you might damage the wires to the heater core and/or thermistor; those are pretty delicate, especially if you can't remove them before cleaning things up. New heater cores and thermistors are fairly cheap, though -- much cheaper than a whole new hotend. Even if you're interested in getting a new hotend, it might be worth at least trying to clean up your existing one, since that will be a useful experience.
     
  8. joea

    joea Active Member

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    Pretty much . . .

    All valid points. I started down this road because of a heater/thermistor related error. Having "coaxed" the thermistor cartridge out, prior to Mark alerting me to the set screw hidden under gunk, it is likely compromised as well.

    I have completely dis-assembled the hot end and cleared the clog. I notice the hot end is free to thread flush up against the heat sink, which I though was proper, however then I note the nozzle cannot thread in far enough to seat on the hot end as it was when I started the tear down. So, if I want to salvage this I have more looking into to look into. Yes, I really said that. Hmm.

    So far, probably needing a thermistor, a heater (genius that I am, I discovered the power supply is labeled 12v, solving that part at least), a nozzle, and probably a compromised "filament channel" inside the heat sink, I am leaning even more toward just getting a V6. Genuine.

    I see them on some reputable sites, even Amazon, for under $60 as a kit. And, I get a new fan and an nifty silicon cover for the hot end in the bargain. Anyone knows of cheaper sources, feel free to speak up.
     
  9. joea

    joea Active Member

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    Yep. And me being a "look before you leap" type too. Tsk.
     
  10. Rod Smith

    Rod Smith Member

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    Your photo looks like your hotend has a bead-style thermistor, although it's out of focus enough that I could well be mistaken about that. I thought that E3D used bead-style thermistors until midway through the V6 series, so I'd expect a V5 to have a bead-style thermistor. That said, I'm not an encyclopedic source of knowledge about E3D hotends, so I could well be mistaken; or you could have some weird Frankenstein's Monster of a hotend. In any event, thermistors are cheap, so if that's your only real problem, it's easily replaced.

    Your description is unclear because, I think, you don't know the correct terms. To that end: There are three parts in an E3D V6's filament path, and they fit together tightly. If they don't, molten plastic can ooze out and gum up the works. (I was actually cleaning up such a mess earlier today!) The parts are, from top to bottom:
    • The heat sink -- This is the big finned thing. It radiates heat, keeping the plastic cool as it makes its way down toward the heat break. In an E3D V6 design, a small piece of PTFE (Bowden) tube extends from the top of the heat sink or beyond all the way down to the top of the heat break. In some clones, the PTFE tubing goes partway through the heat break, too.
    • The heat break -- This is a small cylinder that is, in many ways, the most critical part of a hotend. It transitions from a cool temperature at its top to a hot temperature at its bottom. It's not obvious in most photos because its top part screws into the heat sink and its bottom part screws into the heat block, leaving only a small bit that's visible in a photo, and then only if the angle is just right.
    • The nozzle -- The diameter of the filament path narrows at the nozzle, going from 1.75mm (or a bit more, in practice) down to 0.4mm (or whatever your nozzle's diameter is).
    In addition to these components, there are several more:
    • The heat block -- This is a boxy piece into which the heat break and nozzle screw. In fact, just about everything comes together here.
    • The heater cartridge -- This provides heat and attaches to the heat block.
    • The thermistor -- This measures temperature. It attaches to the heat block.
    I've never seen a V5 in person, so it may be different, but my recollection from videos and whatnot is that it uses the same divisions between components. There are variants in how these items are divided up and fitted together from one hotend to another. For instance, the Dragon and Mosquito hotends blend the heat sink and heat break together in a different way; and most of the components in these designs don't screw together in the same way. In E3D's designs, the heat sink screws into the heat break, the heat break screws into the heat block, and the nozzle also screws into the heat block (abutting the heat break). This can make for some awkward assembly, since when you try to screw or unscrew one part, it could be another that comes undone; you've got to be careful to grab ahold of the correct two parts and apply torque in just the right way to attach or detach the parts you want. (The hotend also mounts to the rest of the printer via a groove mount, which allows the hotend to rotate if it's not tight enough.) This is one of the issues that the Mosquito and Dragon hotends try to fix; only the nozzle screws into anything else, so it's easier to assemble or disassemble things without causing something unintended to unscrew.

    In terms of the fit you're talking about earlier, it's critical that the heat break and the nozzle fit together tightly. This happens inside the heat break, but precisely where depends on order of assembly and how far you screw the first item (normally the heat break) into the heat block. E3D recommends that they be tightened when the hotend is heated up to working temperature. If they're tightened at room temperature, then they're likely to become loose at working temperature, leading to plastic oozing out. The transition from the heat sink (or its included PTFE tube) to the heat break is less critical from a temperature point of view, but if there's a gap, then that can make filament difficult to load, and flexible filaments can jam in the gap. Depending on the details of how you attach everything, there can be a small gap between the heat block and the end of the screws on the nozzle. That's not necessarily a problem, though, so long as the top end of the nozzle is tight against the heat break. Rather than try to describe proper assembly in words, it's better to watch a video. There are a boatload of them on YouTube, like this one (which uses an early production V6 as a model; current versions have bigger heat blocks and cartridge-style thermistors. I'm sure you can find a more recent video online; this one's from a YouTuber who I follow, so I'm providing a link to his tutorial):



    Note that even if you buy a brand-new hotend, you may need to assemble it yourself, or at least ensure that everything is properly tightened at full operating temperature.

    It's not clear to me why you think your heater cartridge or nozzle is damaged, although I may have missed something in your description. The heat sink is almost certainly fine, unless it doesn't screw together smoothly with the heat break. It's possible that the interior of the heat break is scratched, or that the heat break is bent, but again, if you said why you think this is the case, I missed it. Of course, if you're not sure what's damaged and you have the money to spare, spending money on a new hotend may be preferable to spending time diagnosing and fixing what you've got.

    For a genuine E3D V6, that sounds about right. You might save a buck or two here or there, or find a sale from a reputable seller; but $60 is the correct ballpark. To get a V6 for less, you'd have to buy a clone. Aside from Amazon, a few reputable sellers include Partsbuilt (which carries a lot of Robo3D spare parts), Matterhackers, and Printedsolid. (This is by no means a comprehensive list!)

    A Phaetus Dragonfly would also cost about $60, but that's without a heater cartridge or thermistor; those parts will add another $30 or so. A Dragon would be $20 or so more than that, and a Mosquito still more. Of course, if your current heater cartridge is OK, you could forego that expense; but if you've got a bead-style thermistor, or if it's not working correctly, then you'd need to buy a new thermistor for any of these.
     
  11. joea

    joea Active Member

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    Yes, it is bead style. At least there is a little glass like bead where the wires meet. How to reattach it is an open question. Some kind of heat conductive high temp adhesive I do not possess.

    The heat block has a thu-hole machined in it, parallel to the heater hole, which suggests it should have a cartridge type thermistor installed. However, as stated, it measures under 3mm, which is the diameter of the replacements I have seen. Which suggests they would not fit without enlarging the hole.

    Yes, several oddities were noted when loose fitting stuff, such as when the hot end was screwed up tight to the heat break/heat sink, the threads extended into the heat block so far the nozzle could not fit flush up against it. To allow that, I have to unscrew the heat block so there is space between it and the heat sink, which allows it to remain free to rotate. I suppose screwing the nozzle up first then the nozzle/heat block up into the heat sink would resolve that problem.

    However, upon further reflection it seems there should be at least an air gap between the heat block and the heat sink, or the effect of the heat break would be compromised.
    I fear I distorted the heater cartridge when "coaxing" it out, while the set screw was yet unknown to exist. That, plus the uncertainty of which thermistor to use and the mounting/hole enlargement that might be required, nudge me to brush the cobwebs off my wallet and treat myself to a new unit, of known components.
     
  12. Rod Smith

    Rod Smith Member

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    With bead-type thermistors, they're typically just stuck into a small hole and secured there via kapton tape or a screw around the wires (see photos below). This isn't the best way to do it, which is one of the reasons that cartridge-style thermistors have become more-or-less standard these days.

    I suspect you're seeing an old-style V6 (or V5, as I think they're basically the same) heat block. Here's a pair of photos of a V6 clone I bought a while ago as a spare and have never had cause to use (but the original genuine E3D V6 was the same):

    [​IMG]
    The left photo shows the thermistor installed; the bead sticks into the hole in the bottom-left corner of the heat block and is held in place by a short M3 screw in the hole above and to the left of it. (My calipers say the screw hole is about 2.5mm in diameter, and a standard M3 screw does screw into it.) Neither hole goes all the way through the heat block, but it's conceivable it would on some clones. The photo on the right shows the screw and thermistor removed. (Sorry for the poor quality and variable lighting of the photos; these were just quick cellphone photos, but they show what's needed.) FWIW, the Hexagon hotend used as stock on the Robo3D R1+ doesn't even have a screw to secure the thermistor. I don't recall how mine was originally secured, but videos I've seen suggested using kapton tape to secure it, by wrapping kapton tape around both the thermistor and heater cartridge wires and relying on the geometries and friction to keep the thermistor bead in its hole. This always struck me as a jury-rigged sort of solution, but it does work. It's how I've done it when I've done maintenance on my R1+'s hotend.

    Please review the video I referenced earlier. You would not normally screw the heat break all the way into the heat block. The heat break has two sets of threads, the longer of which goes into the heat sink and the shorter of which goes into the heat block. You'd begin assembly by screwing the heat break into the heat block, but only far enough that the lower threads only just completely enter into the heat block; the unthreaded area of the heat break should remain free. You then screw in the nozzle so that it touches the heat break (it won't screw in any further, of course). Even then, it may appear that the nozzle isn't in all the way, as in the above photos, but that's fine. (I've never used this hotend, and it's certainly not fully adjusted or heat-tightened.) When you heat-tighten it, the nozzle will go in a little further, but there's still likely to be a small gap. Again, that's fine. The heat sink will then screw all the way into the larger set of heat-break threads.

    Correct.

    Different thermistors do indeed require different settings in the firmware, and some sellers (especially of cheap Chinese products) often don't properly document their wares, so that can be an issue. (OTOH, most of these cheap Chinese thermistors are of the same type, so using known settings for them will usually work fine.) Reputable sellers will tell you what settings to use, but that will require adjusting the firmware (which is a whole new adventure, particularly for Marlin). The same would be true of a new hotend, but of course if you buy a genuine E3D product, that's at least well-documented. (You could always use a genuine E3D thermistor with a clone V6, a Dragon, a Mosquito, etc. I'm using one with the Copperhead in my Kossel printer.) As I understand it this is a secondhand printer, so you don't really know what thermistor it's got now, so you may need to adjust, or at least check, the firmware no matter what you get as a replacement.

    A deformed or damaged heater cartridge would be best replaced. Those are at least fairly generic, although it's advisable to do a PID tune whenever you replace a heater cartridge. (There are lots of online and YouTube tutorials on PID tuning, but I don't have any URLs handy.)

    A new thermistor and heater cartridge will get you to 1/3 or 1/2 the cost of a new genuine E3D V6, especially if you go with name-brand products -- and of course if you've got a bead-style heater block, an upgrade to a cartridge-style has merit, so I certainly won't try to deter you from going that route. As noted in my earlier replies, there are other options beyond the E3D V6. The E3D V6 is a good hotend and it'll work fine; I've mentioned others earlier so that you don't buy a V6 and then immediately suffer buyer's remorse because you didn't get the "latest and greatest" hotend technology. You should plan on setting your firmware's thermistor values and doing a fresh PID tune on the new hardware, no matter what you buy.[/QUOTE]
     
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