BondTech BMG Extruder for Delta Recommendation?

  • Hi,

    Anyone have any pros/cons/recommendations re; the BondTech BMG extruder for usage with a delta printer? I've heard that this extruder can adequately move soft filament?

    Also, I'm toying around with employing a flying mount for the extruder, but the extruder motor that is on the stock AnyCubic extruder is a 'full-size' NEMA-17 which seems a bit large for a flying assembly. Any recommendations for a different motor for the flying mount?

    Thanks in advance,


  • I turned my linear plus into a flying extruder using the stock motor and a BMG.
    It printed well
    IMG_20191001_215451.jpg IMG_20191001_214329.jpg

  • @jay_s_uk

    Thanks for the photos. Your Linear Plus looks a lot different from what AnyCubic sold me as a Linear Plus.

    So you used the AnyCubic extruder stepper. Where did you get your flying mount?

    Thanks again, 3mm

  • Moderator

    Bondtech BMG is a good choice of extruder for any printer, particularly if you're going to be printing a lot of flexible/soft filaments due to it's double teeth. You'll want the extruder as close as possible to the hot end for soft filament, which is more difficult on a Delta. You can use a flying extruder, or an extra vertical axis to support the extruder. You can also make the extruder much lighter by using a 'pancake' NEMA 17 (eg see Bondtech motor page) which may allow for direct mounting it, possibly at the cost of some speed (though you usually can't print soft filament really fast anyway). Alternatively, look at the new E3D Hermes (no details on E3D website as yet), which uses the same principle, but is more compact. Or the Zesty Nimble remote extruders. Forum members have tried all of these approaches!


  • @3mm
    I used these adaptors to mount the flying extruder to the frame and I used this adaptor to mount the actual extruder.

    I turned my frame upside down so the electronics are at the top away from the heated bed.

  • I second jay's flying extruder approach.
    If you're using a smart effector, you can use the 3 extra holes to affix the extruder mount to the effector, so that the bowden tube isn't the only thing connecting them.


    Not the greatest picture, but you can see the 3 sets of twisted pair 24(i think) gauge aviation safety wire going up to the extruder. I anchored them to 3 M3 bolts going into the 3 otherwise-unused holes in the smart effector. Then they just wrap around the springs at the extruder mount. My bowden tube is actually 'too long' for this but that means there is just more force keeping it held in place between the hotend and extruder.

    Bondtech extruders are great. You'll never see stripped filament again.
    instead, the bowden tube will strip itself out of the collets if you exceed the volumetric extrusion rate your hotend can do. I'd say this is kind of a con. stripped filament is easier to deal with than stripped bowden tube. But the bowden tube is more durable, so it would happen less often.

    I think the standard kit BMG comes with a little pancake stepper. Still a nema 17, but its much smaller than the one in jay's pic there. His is a clone, so maybe that's why.

  • @3mm said in BondTech BMG Extruder for Delta Recommendation?:


    bondtech is great extruder, but I'd think about flex3drive for delta, especially if you wanna print flexibles... much better solution IMO, especially the new G5 rocks.. it's light, fast, durable, printable and open source 😄 .. Jason overdid himself with this one 🙂

  • administrators

    I use a genuine BMG on my delta and I am very happy with it. I don't yet use a flying extruder.

  • @dc42 said in BondTech BMG Extruder for Delta Recommendation?:

    I use a genuine BMG on my delta and I am very happy with it. I don't yet use a flying extruder.

    Me also. I have a large-ish (two meter tall, 600mm Z printable) with about one meter of bowden, and an AKL+ with about 1/3 meter of bowden. Both with BMG mounted on a tower, about 2/3 of print height.

    Both will print some flex materials; neither will print the really floppy stuff.

    LOVE the BMG.

  • I have a BMG on my mini kossel with 500mm bowden and it can't print really flexible filament. Everything else prints very nicely, it's the best extruder I have tried. I also have a kossel xl that is fitted with a flex3drive and that prints flexibles OK.

  • @jay_s_uk, DrofTarts, oryhara, smece, DC42, Danal, burtoogle, et al,

    Thank you for all the recommendations.

    I purchased a BondTech BMG from FilaStruder last evening & a pancake (42STH25-1404) stepper with a metal bowden tube coupler-adapter.

    @jay_s_uk, your turning your printer upside down, heh heh, that's cool! I did not think of that. I planted my DUET-E controller in a forced-air box on a tower about six inches above the base, however, that may be the source of a side centric print artifact I am seeing..

    @oryhara, I presume that the chains are intended to constrain the flying platform from swinging about too much? And may I ask, what is ghosting?

    Initially I'll mount the extruder on a tower and guide the filament using 511mm length of bowden PTFE tubing to the SmartEffector/E3D-V6 hotend, although, later I intend to implement a flying extruder platform. I desire to experiment with both deployment arrangements.



  • @3mm Ghosting is repetitive patterns on your print following a point where the hotend changes directions...things like a hole or notch in your print and you will see similar looking artifacts on your prints following it.

    If you search 3d print ghosting on google, many pictures will come up showing this.

    This is a perfect example of it.

    alt text

  • @JamesM

    Hi JamesM,

    Thanks for the photo. Do you know what caused this artifact? Was the problem remedied?


  • @3mm affirmative.
    And without them, the only thing connecting the effector to the extruder is the bowden tube. Which is subject to force in the same direction from the extruder pushing filament through it. The springs are pulling it in the same direction, adding to the force on the bowden tube. By having the wire connecting them, and the tube a bit too long, it is now only subject to the force of the filament going through it.

    This has another benefit(which i just noticed): The springs for the flying extruder don't reach their slack or near-slack position, so they maintain a more constant force on the extruder. They make less noise.

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