BMG vs clone test

jens55

The other day, I was printing some smallish parts. They printed fine at 0.2 mm layer height but when I tried switching to 0.1 mm layer height, the hot end consistently plugged up. Now the problem was not the nozzle itself but I believe the heat break was causing the issue. Heat creep from the low flow rate is suspected to have expanded the filament in the heat break causing it to have a bit more friction and preventing the extruder from being able to push the filament through.
I tried all kinds of things to overcome the issue but was unable to do so. 0.2 mm layers printed fine, 0.1 mm didn't. For some reason I decided to select a different infill and behold the damn thing printed at 0.1 mm and even at 0.05 mm it was working fine. I reverted back to the previous infill and 0.1 printed fine, 0.05 showed a couple of small issues.
Well damn, there goes my theory of what was happening.

I had always wondered about the clone BMG extruder I was using and, although it seemed fine, was it as good as the real thing. It was driving me nuts because nobody seemed to be able to answer this question.
Curiosity got the better of me and I decided to order the real thing. Here is the rundown of the two. Note the cost is in Canadian dollars to my door. This comparison is with one and only one clone - no guarantee that the next one would be the same.

Real ............................................................Clone
$110 .......................................................... $13
Cardboard box...........................................Nice re-usable clear plastic box with a lid lock
No hex keys, no Bowen adapter ............ included keys and adapter
The adapter can be purchased for $11
SLS printed housing ..................................injection molded housing
I can not speculate on the quality of bearings between the extruders
The clone housing was a bit different overall as it was injection molded but the outside
was identical.
Brass coloured pinion gear .................... Silver (steel?) coloured pinion gear
Black plastic gear to mesh with pinion ..White plastic gear to mesh with pinion

Overall, the two extruders seemed to be pretty much identical.
Although not tested, I believe the feed gears of the clone are hardened just like on the real McCoy.

Since I had no reliable way to fail a print with the clone extruder, I decided to do a torture test. 1000 cycles of retract and feed of 100 mm each. A little over an hour of continuous back and forth. The test printer was using a long Bowden tube and I had about 700 mm of the filament in the tube (not quite to the actual hot end)

I cleaned up the clone as well as the stepper motor that had some black dust on it and started the test. Once done, the clone extruder came off and was inspected.
I was using white petg for the filament.
There were minor bits of white dust on the infeed and outfeed of the extruder and virtually none in the serrated gear section that feeds the filament.
There was however a substantially amount of black dust. I examined all the bits and I have not been able to find where this dust comes from. I suspect that it might be the fit between the pinion and the plastic gear but the gear is white and the dust is black. A big puzzle that I can't explain!
I cleaned up the black dust from the top of the stepper motor and installed the real thing and ran the 1000 cycles.
Inspection of the extruder showed a little white dust from the filament - about half of what was in the clone extruder. Again, the amount was totally minor.
There was none or not noticeable amount of black dust.

From this I gather that the clone is likely to wear out earlier than the real thing. Hopefully, in time, I will be able to determine what causes the black dust.

Now to the real obvious difference between the two:
The feed path of the filament in the clone is slightly off from the feed rollers. The result is a good teeth impression on one side of the filament but a rather smaller impression on the back of the filament. The real BMG had what appeared to be pretty much even indentations on both sides of the filament. This would result in a better feed force on the filament and I suspect would completely eliminate the feed problem I had when all this started.

So, is it worth $121 ($110 plus the Bowden adapter) for the real thing compared to $13 for the clone (which included a nice storage box) ..... No way unless you had some very specific operating conditions.
I would also argue that since I can buy 9 clones and have a bit of change for the price of one true BMG, chances are that some of the clones wouldn't have the tiny offset between filament feed and feed gear. Who knows ......

I like to buy the real thing whenever it makes sense. 1.5 times the clone price - sure, I will go with the real thing. Twice the clone price .... I would probably choose the real thing. 9 times the clone price ..... not likely unless I can't avoid it.

Let's face it, there is really nothing much to these extruders ..... I have no idea how BMG came up with the price. I am thinking that development costs have long been recovered and there is no reason to maintain that high cost.

In my case, I will eventually change to water cooling of my hot end and hope to reduce the heat creep which in turn will negate to squeeze the highest feed pressure possible out of the extruder. Going direct extruder would also make a big difference.

To sum it up, if you need very high filament feed pressures than by all means, go with the real thing after you have optimized the feed path.

I hope this will clear up things a bit for other people tat have been wondering.

Edited to make it readable

jens55

This post is deleted!

deckingman

@jens55 You could have simply said that the clone has issues in that it grinds the filament due to the asymmetric nature of the two hobbed bolts, and that it will fail prematurely due to some defect causing black dust from the casing to appear. Yet because of the price difference in your part of the world, you would rather buy the clone and change it often. Which of course, is your decision. But you haven't factored in the cost of the failed prints, which will be significant when the clone fails say 1.5 days into a 2 day print. Nor the wasted time in hours in frequently changing the extruder. And then of course there are the ethical factors of supporting communist state owned companies that steal other people's intellectual property. But that's entirely between you and your conscience.

jens55

@deckingman, yes I could have said that but it would have implied that the clone is no good. What I was trying to express is that for all but a tiny case of users, the clone is perfectly acceptable.
It takes literally a minute to change out an extruder and nothing in my review indicated that 'changing the extruder often' is a requirement. I do not know where the dust is coming from and as such I can't even guess as to the reduction in extruder life (if any). It might just be a bearing spinning in the housing and a single drop of sleeve retainer compound could fix it. I checked the case very carefully and did not see any chafing spots.
Yes, failed prints is a potentially costly issue but as I pointed out, pushing the filament harder is a bandaid solution when one should sort out why the extra push is required.
I run a mix of real and clone stuff. I am more than willing to support those who advance the hobby by developing new stuff. As I said, I am willing to pay a premium - within reason. In my humble opinion what BMG charges for their extruders is totally unreasonable. Of course I can only guess at that but I am quite comfortable with my guess and my decision of running clone extruders.
If nothing else, if I have more extruder issues in the future, I have a real BMG to swap in and if that fixes things I know that I have issues in the filament feed system that need sorting. Feed pressure from the BMG clone is much higher than the standard extruder that came with my printer. Do I need a tiny bit more feed pressure .... well it can't hurt if the marginal improvement comes at a marginal price point but there is the catch. If money was no object I'd have a 1000 lb commercial printer sitting here that doesn't rattle the whole house while it's printing but it just doesn't make sense unless you are doing this for a commercial venture.

jens55

Thinking this over a bit, if the original was in the $30 to $40 range, I would be running originals. The bit about "that's entirely between you and your conscience" is a cheap shot as far as I am concerned.
If I was to look in your drugs cupboard, would I find "Tylanol" or would I find the generic drug acetaminophen? Of course this is only one example but I bet that your life is full of examples where the price vs functionality issue has come up.
Sure, I'd love to have only Snap-On-Tools but I can remove a bolt just as well with a wrench from Canadian Tire at 1/10th the price and if I have a really stuck bolt where I need the best of the best I can buy a single Snap-On-Tools wrench instead of a whole set.

Patents aren't meant to provide perpetual protection, but an initial exclusivity to recoup your initial research and development; so both your examples kinda fail on that point - generic drugs are only available after patents expire so its generally considered the patent holder have had enough time to profit and its time for capitalism to do its thing.

For some drugs I buy the "original" still because there are subtle differences in the non active ingredients even though the generic copies have an identical active ingredient, but once the patent did expire the price of the "original" did drop to face the generic competition.

jens55

Just had a look-see on the Bondtech site and I was unable to find any mention of 'patended'
I mentioned black gear vs white gear in my review - apparently the BMG extruders used to have white gears but they were changed to black as the white showed the black dust too much (ie the change was purely to hide the black powder)

fma

I built a Nema14 based custom extruder using BMG clone gears, and I didn't notice any filament grinding, nor black dust... I printed several kg of filament (especially during french lockdown), and a few long run prints, without any issue.

DocTrucker

I've run both, and at the moment run clones because I can't afford the genuine. I'll upgrade when income allows.

My clone BMGs have given me far less trouble than my RepRap or Genuine Titan extruders. So far one hasn't croaked on me and I had two of my six machines running them for six weeks where I was hammering the machines with the virus face shields.

Regards costs the Bondtech team will be facing the dahmed if you do, dahmed if you don't situation. Chinese clone stuff can go injection molded because both overheads, labour, and materials are so cheap. This means there isn't the ~£10k hit that needs to be taken in manufacturing costs to move into injection molding. For more comparable environments to the UK this hit also forces a design freeze, because the tooling would nees to be rebuilt for any change. So BMG stay SLS and remain flexible in design while maintaing tollerances that are fit for purpose anyway. Yes there are some economies of scale with SLS but they will max out with a full build which is likely in the region of 125 parts, rather than needing part cost savings to give some return on investment for the tooling.

Finally of course if the current cost model is brining in what they need for the business why drop further?

jens55

@fma said in BMG vs clone test:

I built a Nema14 based custom extruder using BMG clone gears, and I didn't notice any filament grinding, nor black dust... I printed several kg of filament (especially during french lockdown), and a few long run prints, without any issue.

As I tried to express, there are very few circumstances where he clone fails (or grinds). The black dust could be an issue with just that one clone for all I know.
I had another look at things this morning and I still haven't figured out where the black dust is coming from. Other than gear to gear, there are no parts touching each other. If the dust is generated as gears are wearing in, you would only notice that if there was a substantial load on the gears (from let's say a long Bowden tube or the tension spring being real tight).
All-in-all, I stand by my assessment that a clone extruder is a far better value for your money.

deckingman

@DocTrucker In the OPs part of the world, the clone manufacturers also enjoy the benefits low or zero import tariffs compared to EU based manufactures because the EU trade agreement is yet to be ratified whereas the agreement with the CCP has been in place since 2014. EU member states tend to pay their workers a decent minimum wage too, rather than using modern day slave labour such as the Uighurs. Also, part of the OEM profit goes towards developing future products, whereas all the cloners have to do is sit back and wait, then steal that intellectual property. Then of course, the cloners are all part of the state so they don't need to make a profit. Or rather, any profit they make goes to the state to help fund their inexorable military build up and the next war.

jens55

@DocTrucker said in BMG vs clone test:

Finally of course if the current cost model is brining in what they need for the business why drop further?

I think that this is exactly what is going on. They probably did a study of overall profit vs price and found the sweet spot. Unfortunately their profit sweet spot does not match the value sweet spot the consumer gets to experience. Note that there is nothing wrong with making a profit. I just feel I get far better value for my money with a clone.

@deckingman said in BMG vs clone test:

lso enjoy the benefits low or zero import tariffs compared to EU based manufactures

eu will drop those rules next year, making all imports subject to VAT at least to even the playing field (we already have similar rules and i must say i don't think it'll have the intended effect, but the government get their slice so theyre happy)

jens55

@deckingman said in BMG vs clone test:

@DocTrucker In the OPs part of the world, the clone manufacturers also enjoy the benefits low or zero import tariffs compared to EU based manufactures because the EU trade agreement is yet to be ratified whereas the agreement with the CCP has been in place since 2014. EU member states tend to pay their workers a decent minimum wage too, rather than using modern day slave labour such as the Uighurs. Also, part of the OEM profit goes towards developing future products, whereas all the cloners have to do is sit back and wait, then steal that intellectual property. Then of course, the cloners are all part of the state so they don't need to make a profit. Or rather, any profit they make goes to the state to help fund their inexorable military build up and the next war.

While I agree with this sentiment in some respects, it fails to see the total picture. Like it or not, a very large percentage of products or part of products are manufactured in China (or other low cost manufacturing countries). You can't simply pretend that China is not part of the global manufacturing system.
It would be nice if you could but you'd see every product go up in price by a factor of ten or more and nobody could afford to buy anything. If we would simply say "let's not buy anything from China" then our way of life would pretty much grind to a halt .... and that's assuming we had the manufacturing capacity which we don't have.

jens55

While I dn't really want to stirr the pot, it would be really interesting to look at Bondtech overall and see what would happen if all of a sudden it became illegal to source anything out of China.
Where does the raw material for their SLS printed cases come from?
Where do the SLS printers themselves come from? What about the components of the printers? Where did that ballpoint pen come from that the shipper is using or the printer that prints the shipping labels etc etc etc.
I think we would quickly find out that there is no way we could produce anything and it would take centuries to bring up the manufacturing machine to be able to produce our own bits (at a much much higher price)

fma

And without China, where would we find all these beautiful viruses?

@fma said in BMG vs clone test:

And without China, where would we find all these beautiful viruses?

I'm sure africa has more than ebola to offer, as will any place where humans can contact new species of small and large living things.

DocTrucker

Taken to extremes the majority of components on Duet boards are likely sourced from east asia. Likewise I think many of our favoured companies sub contract manufacturing or source sub components from similar locations. Large 'capitalist' companies have basically built the 'communist' east asian manufacturing power house.

deckingman

@jens55 said in BMG vs clone test:

While I agree with this sentiment in some respects, it fails to see the total picture. Like it or not, a very large percentage of products or part of products are manufactured in China (or other low cost manufacturing countries). You can't simply pretend that China is not part of the global manufacturing system.
It would be nice if you could but you'd see every product go up in price by a factor of ten or more and nobody could afford to buy anything. If we would simply say "let's not buy anything from China" then our way of life would pretty much grind to a halt .... and that's assuming we had the manufacturing capacity which we don't have.

You do have the manufacturing capability - you could have bought a locally made Dyze extruder.

This is probably not the time or place for this discussion but I think the way of life as we know it may now be relatively short lived. For sure, 30% of everything worldwide is manufactured in China (including Duet boards unless I am mistaken). China also owns the majority of the of the worlds shipping and much of the worlds infra structure which moves those goods around the planet. Then if you look at what China is doing to it's own people, the recent events in Hong Kong, their activities in the South China Sea, the territorial disputes they current have with Russia, India, Kazakhstan, Kyrgyzstan, Mongolia, Laos, Philippines, Malaysia Indonesia, South Korea, North Korea etc, something has to give. Then there are the swingeing economic sanctions that they have imposed on Australia for daring to ask for an independent enquiry into the origins of Covid. The western world is starting to wake up and smell the coffee but it may already be too late. After Hong Kong, Taiwan will be next on their list. Will the rest of the world stand by and let that happen? If so then what? The entire South China Sea area? The Philippines? Malaysia? Sooner or later, something will give and then we really are stuffed.

deckingman

@DocTrucker said in BMG vs clone test:

Taken to extremes the majority of components on Duet boards are likely sourced from east asia. Likewise I think many of our favoured companies sub contract manufacturing or source sub components from similar locations. Large 'capitalist' companies have basically built the 'communist' east asian manufacturing power house.

East Asia is fine. Nothing wrong with South Korea, Japan, Vietnam, Malaysia etc....