Before Hermera, long, long ago…
Before the E3D Hermera was released for sale, one of the best dual-drive extruders on the market was the Bondtech BMG.
This is a beast of an extruder and is able to push out even the most stubborn of filaments without even breaking a sweat, but it’s expensive. very expensive.
So it was China to the rescue again with clones, clones and more clones, and from just $14 US.
So, just how good are these clones and are they worth your coin?
Join me as I review the Bondtech BMG extruder clone!
note: If you would like to buy any of the products in this review, please use the provided affiliate links below to help support my work.
I chose the one without a motor and got this pancake stepper as well saving about $2, but more importantly the pancake stepper is lighter and more compact than the one that comes in the full kit and thanks to the BMG’s 3:1 gearing ratio it is plenty powerful enough.
Beware though that you may have to adjust the stepper drivers current if you use the pancake motor so it doesn’t overheat (mine runs approx. 40% current on an A4988 stepper driver) if this is something that scares you then just get the full kit.
If you already have a direct-drive extruder and you are looking to upgrade, then you can buy the kit without the motor and save some hassle.
The BMG is made to fit around E3D’s V6 hotend but ships with a Bowden adaptor, meaning its a drop-in replacement for most Bowden printers such as the ender 3 and you don’t even have to buy a motor.
If you want direct-drive though and can’t justify buying a genuine V6 hotend a good alternative is to buy a clone and fit a genuine E3D nozzle (MASSIVELY improves stringing and retraction!), and if your willing to upgrade further E3D’s V6 sock and block upgrade kit is a great kit (I have the sock and block kit and a nozzle X!).
The extruder ships slotted together around the Bowden adapter, so if your going Bowden it’s simply a matter of attaching the drive gear to the stepper motor shaft (Beware! the drive gear goes on “upside-down”) and bolting the BMG clone to the motor.
If you are going with a direct drive setup though simply un-slot the two halves, place your V6 hotend inside, and slot it all back together.
Attaching the BMG to a direct-drive printer is easy, all you need is a mount that slots between the stepper motor and the BMG.
The kit does come with a generic mount, which you can use but I decided to print my own with built-in mounts for the part cooling fan and my inductive bed levelling/Z-axis endstop probe.
Make sure your hotend is facing the right way before you tighten down the extruder!
This. thing. rocks.
My old mk8 style Bowden extruder set up with it’s little hobbed gear was, well, rubbish.
After a few months use it would struggle to print PLA above about 40mm/sec without noticeable under-extrusion and it always hated the PLA expanding every time it retracted and all prints with it had a few missed layers and lots of prints failed from jams.
The BMG has powered through all my filaments without a hitch and grips the filament like a champ.
One minor problem I do have with it is that sometimes when using a reverse Bowden tube (a “Bowden” tube that guides filament to the extruder and isolates the movement of the print head from the filament, giving a smooth, continuous pull on the filament and extruder), is that sometimes the filament catches on the fitting that holds the PTFE tube and doesn’t reach the drive gears.
This is easily fixed though, by simply cutting the end of the filament at a different angle to the one already there (cutting the end of the filament at an angle allows easier passage into your hotend).
So, should you buy one?
If your on the lookout for a good extruder to upgrade your 3D printer with than this is probably the best choice, it’s very powerful and lighter than a metal extruder, performs like a champ and allows for very high printing speeds.
I can’t see any reason to get a genuine Bondtech apart from supporting them, but most people with an ender 3 don’t have $90 US to spend on an extruder and the clone does all that it’s genuine cousin(?) can do with cash to spare!
Steps/mm: 415 with 1/16 microstepping
Gearing ratio: 3:1