BMG CLONE extruder issues
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@jens55 even the original chimera had issues with retraction
you had to really fine tune it to work ok, and that's very precisely machined piece of kit, the clones I tried are useless the contact between heatbreak and the heatsink is bad, you have to use a lot of good silver paste and they still don't cool the heatbreak enough, 40C on the heatsink can easily be 60+ on the heatbreak and it will block your PLA. The heatbreak itself is a totally different story, the ones I tried (and I got bunch as I purchased some chimera, cyclops and kraken clones to do some testing) the inside is not smooth at all.. originally I was thinking that getting just original heatbreak + nozzle from e3d and PRC made heatsink and heatblok will get it done but heatsink block is also poorly machined so the contact between heatsink and heatbreak is "2 lines" instead of a surface... it works ok for pushing filament in but as soon you start retracting it quickly heat up and blockthere are many different clones of BMG (some very good quality, many not really) but I have never seen a good clone of chimera/cyclops/kraken as you really need those machined precisely and you can't do precission milling cheaply, not even in china
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<sigh> ok, understood.
I will carry on testing to figure out what is going on.
Before changing to the white filament I had nowhere near the amount of trouble so at this point I am still suspicious of the filament.
My next step will be to switch back to black and try that while drying (just in case) the white filament. -
@jens55 said in BMG CLONE extruder issues:
@deckingman, yes, I did read your report re the BMG's when I first tried to look for answers.....................
It was the two pictures at the end of the post that I wanted to draw your attention to. https://somei3deas.wordpress.com/2018/05/11/bondtech-bmg-vs-e3d-titan-extreme-retraction-torture-test/
Especially the one showing the inside of a genuine BMG after 26,000 plus retract/un-retrcat cycles. The other one shows the inside of a genuine E3D Titan under similar (admittedly extreme) conditions. Both extruders appeared to grip the filament just fine but the pictures speak volumes.Edit. So while the clone might appear to be gripping the filament just fine, the reality might be somewhat different.
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@jens55 might be worth tweaking the temperature (particularly if the black filament works better). I know some filament brands say that black requires a slightly higher temperature than other colours.
I also second what the others have said about genuine components. I have a homebuilt printer with 700mm bowden. Originally I fitted a cheap cloned titan extruder, cloned V6 hotend, and poor quality PTFE tube. It just about worked but needed a lot of tweaking and I often had filament grinding etc. I now have upgraded to a genuine BMG, e3D V6 and capricorn XS PTFE. I cant say which was my original problem, but the system is so much better for using proper parts. Particularly with a long bowden, I think a lot of different factors can play, and several small gains can combine and add up to a lot performance improvement. That and a bigger credit card bill!
sorry it might not be news you'd hoped for...Home-built CoreXY, Duet Wifi, Chimera direct drive, 2x BMG, 300x300x300 build volume
i3 clone with a bunch of mods -
@deckingman, I had seen the pictures but obviously didn't examine them close enough. My extruder looks like the Titan on the inside, full of bits.
I have come up with another possible explanation of what is going on. It will require more testing before I can give more details. -
@jens55 said in BMG CLONE extruder issues:
Hardened teeth isn't an issue, they grip just fine and I do not use abrasive filament. I can however see a possible issue with the particular cut or smoothness of the grooves. I would just like to eliminate all issues before I spend over $100 (CDN) for mostly a piece of plastic ... especially since this is the first time I have seen the issue.
You can save some money by just buying the original drive gear kit from bondtech. Genuine resellers in your area might have them available as well.
<>RatRig V-Minion Fly Super5Pro RRF<> V-Core 3.1 IDEX k*****r <> RatRig V-Minion SKR 2 Marlin<>
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@engikeneer, the only thing 'original' I use is Capricorn tube
I will work this out one way or another and if an original BMG is required for reliable printing than so be it. It's only cash ...... and the grief and aggravation of all the failed prints is causing the few hairs I have left to go gray.
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@oliof, while it had occurred to me that I could just buy the drive gears, I think I will always wonder what I am missing by not using the full product. If things didn't work for some reason or other then I would have no real answer if the original parts are better than the cloned parts.
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@jens55 correct, you would at least want the shaft gear and the POM gearwheel as well, and then the internal geometry of the clone could still be detrimental to filament path etc....
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The old adage comes to mind - "Buy cheap, buy twice".
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@jens55 said in BMG CLONE extruder issues:
what I am missing by not using the full product.
Long time ago I understood the "I'm not rich enough to buy cheap things" but still from time to time I go and purchase a clone. And EVERY SINGLE TIME it cost me so much time and nerves and ... every time I ask myself wtf I did it.
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deckingman and arhi ......
Yes, I bought the clone version. Yes, buying cheap does bite me in the ass more times then not.
In this case, if I remember correctly, I even asked (possibly in this forum) about clone vs real thing and the general consensus seemed to be 'the clones work real well'.
In deliberations about buying clone vs the real thing, I generally am more than wiling to pay roughly twice the money for the real thing. In this case it was a $15 vs $120 decision (Canadian) and that actually made the decision quite easy. Just like my decision to buy a real Duet vs a clone - I think the up charge was less than 50% so no question.
Believe it or not, the bowden adapter that does not seem to come with the real thing costs the same as the entire clone extruder which comes with the bowden adapter. It just seems to be WAY over priced for what you get.
Given all the grief I am currently experiencing, I am STILL thinking that the clone BMG was a good buy even if it means just using the bowden adapter from it!My latest test print using black filament instead of white is humming along nicely with no apparent issue as of yet. I even went back to my previous pressure advance settings. What I did do though is changed to the second extruder path because I have a 'hunch'.
I consider myself suitably chastised for buying a clone product and I am hanging my head in shame ...... but the story isn't finished yet and there might be a surprising plot twist coming up (or so I hope)
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@jens55 said in BMG CLONE extruder issues:
'the clones work real well'.
I have BMG clone that works awesome, identical to original, two original's and two awesome clones (that were not much cheaper than original, I ordered because originals were impossible to get at the time) but I also have few clones that are unusable
so ..$15 vs $120
when the difference is that much there's usually a reason. the good bmg clones I have were 70eur each
Anyhow, even the totally crappy clones should work. They don't have the force of original one, nor can dig in as original one, but if they are grinding like yours have they are experiencing issue in the hotend. The different filament can have few C higher Tg and that will make it just enough to not block the heat break. So that, imho, proves that the problem is poor cooling of the heatbreak.
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@arhi said in BMG CLONE extruder issues:
the good bmg clones I have were 70eur each
That's very expensive for a clone. Did you order directly from China or from a local store?
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Apologies for going off topic but it's the old story. OEMs plough some of their profits back into developing new products. They also support those products. The cloners sit back and wait, then when a new product gets released, they make a cheap copy that everyone buys. Part of the reason why the clone is cheaper is that they don't have any development costs or support costs. If an OEM produced an item that was faulty or otherwise not fit for purpose, they would get an exchange or refund. Not so the cloners. Try asking for your money back from AliExpress. Try getting support.
The stats for my blog show a great deal of interest from China every time I post something related to the 6 input hot end I'm trying to develop. This could be the first hot end that is cloned before the original has been made into a working prototype. I'm sorely tempted to publish the design with known flaws and claim that it works, wait for the cloners to make their tooling, then release the real design.
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Queue evil scientist laughter ...
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@zapta said in BMG CLONE extruder issues:
@arhi said in BMG CLONE extruder issues:
the good bmg clones I have were 70eur each
That's very expensive for a clone. Did you order directly from China or from a local store?
directly from PRC .. but as I say there are good and there are not so good ones, I have some that were 30$ that are utter garbage ...
@deckingman amen! but not all of the cloners are like that, I know at least one company that shoot % of the money to the original designer and one company that offered to pay royalties
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@arhi said in BMG CLONE extruder issues:
@deckingman amen! but not all of the cloners are like that, I know at least one company that shoot % of the money to the original designer and one company that offered to pay royalties
That's good. Care to name them?
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Using the secondary extruder path (still a BMG clone extruder), black filament, no retraction but full pressure advance (with the resulting retraction), I have achieved a beautiful model. Disassembly of the extruder showed zero filament dust.
The white filament has been loaded and a new print is on the go.
It is looking like there might be a 'speed bump' in the primary extruder path. When I say 'speed bump' I mean a transition between ptfe tube and some internal structure in the hot end that is causing an intermittent hangup. I suspect it hangs, grinds, retracts and then feeds in correctly eventually. This causes poor extrusion.
If the now loaded white filament is printing successful then this would pretty much confirm this suspicion and I can look at the primary feed path in the hot end.Thanks for all the help guys! I will follow up in about 20 hours when the new print is finished.
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@deckingman said in BMG CLONE extruder issues:
"Buy cheap, buy twice".
Is it so? This implies that more brand name products are sold than clones.
Clones have an important role of popularizing the technology and in the case of OSH, it's by design.
