3D Printer Extruder Comparison
A new extruder can significantly improve your print quality and speed. If you are still running a BMG extruder you should know there are better options out there.
Popular extruders
Let me give you a quick walkthrough of the popular extruder options. I will do this in chronological order so you can better understand the extruder evolution over time and why some of them are more common than others. For example, BMG comes with a lot of printers out of the box and there are the most mounts made for it but that’s mainly because it’s been out there the longest and it’s still the most affordable option today.
BMG
BMG (Bondtech Mini Geared) extruder was originally developed by Bondtech but because of its success it has been cloned by many others. It is the most common extruder in use today and comes included with a lot of 3D printers. This extruder can be used in both direct drive or bowden configuration. However, it’s driven with a large NEMA 17 stepper motor and it’s rather big and heavy for direct drive setup. The dual drive gear system provides good grip and allows to print flexible filaments in direct drive configuration. You can find these at around $40.
E3D Hemera
E3D Hemera takes a totally new approach to 3D printer extruders. It combines an extruder and a hot-end in a single unit. This approach means you can make the combo more compact and achieve a shorter filament path between the extruder and the hot-end. The filament path is also all metal which makes it better at pushing flexibles and abrasives.
The big disadvantage of Hemera approach is the lock-in: you can’t use different hot-end*, you can’t use different stepper motor** and you can only buy spares from E3D. You would also likely expect this compact package to be very lightweight but it comes in close to 400g which is easily achievable with other extruder and hot-end combinations.
* You could in bowden setup but you’d loose the whole point of Hemera
** E3D uses an unique motor for Hemera, it’s based on NEMA 17 design but not compatible
Orbiter 2.0
Orbiter extruder is the only extruder using planetary gearbox. The design allows very high gear ratio (7.5:1) while maintaining a compact and light package. It’s powered by a smaller NEMA 14 stepper and overall weight with the stepper is just 135g. High gear ratio combined with high torque stepper motor allows it to achieve a lot of filament pushing force (8-10kg). It also uses slightly larger dual drive gears for better filament grip (12mm vs typical 8mm on BMG based extruders). Orbiter also has a unique metal filament exit guide which makes it better at pushing flexibles and abrasives than most other extruders. I think it’s a great extruder if you need more filament pushing force or print a lot of flexibles.
I recommend reading this post from Orbiter author to better understand all the benefits of this extruder.
Sherpa Mini
Sherpa Mini* is a compact and lightweight open source extruder. It’s using BMG components with a smaller NEMA 14 stepper motor. Due to its compact design and a smaller stepper it weights just 127g. Sherpa Mini uses BMG gears but due to different pinion gear on the NEMA 14 stepper has 5:1 rather than 3:1 gearing ratio. It’s an easy upgrade option for people who already have a BMG extruder: you need to get a NEMA 14 stepper and print a few parts.
* Sailfin and HextrudORT are very similar designs that you may prefer in certain circumstances but they are less popular and you may need to design your own mount to use them.
Bondtech LGX
LGX (or Large Gears eXtruder) is a newer extruder from Bondtech. It comes with larger 18mm drive gears (hence the name) which provide more surface area in contact with the filament to improve the grip. It’s powered by a NEMA 17 stepper and comes in at a similar weight as the original BMG extruder. LGX is one of the most expensive ($100) extruders out there.
Bondtech announced LGX Lite version which is more compact and lightweight (141g). It will start shipping in late 2021 and I will update the post when I get a chance to try one but the specs look promising.
Comparison table
| BMG | E3D Hemera | Orbiter | Sherpa Mini | Bondtech LGX | Bondtech LGX Lite | |
|---|---|---|---|---|---|---|
| Release date | 2017 March | 2019 November | 2020 March | 2020 August | 2021 February | 2021 October |
| Drive gears | 8mm | 8mm | 12mm | 8mm | 18mm | 18mm |
| Gear ratio | 3:1 | 3:1 | 7.5:1 | 5:1* | 6.84:1 | 9.576:1 |
| Weight | 220g | 388g** | 135g | 127g | 218g | 141g |
| Price | $40 | $120** | $60 | $50 | $100 | $70 |
* Gearing can be boosted to 6.25:1 with an 8-tooth stepper motor.
** E3D Hemera weight and price includes an integrated hot-end. A popular V6 hot-end would add about $20 and 50g to the other extruders.
Which one?
I think the best choice for most people is Sherpa Mini. You can build it from your old BMG parts or purchase one at an affordable price. It also has the best community support with a lot of mounts already designed for different printers.
If you are looking for better performance with abrasives or flexibles then the Orbiter is the best fit for you. It’s only slightly more expensive but its larger filament drive gears and higher gearing ratio can push filament harder. However it’s also a little bulkier and more complex with its custom parts.