Twice the gears, twice the fun! Kinda…
Buy a Bondtech Extruder
Hello everyone, Tom here, and right now i’m trying to catch up with all the things i’ve been wanting to have a look at and review. And one of those things is the Bondtech Extruder, which i’ve had sitting around for way too long.
Now, the bondtech extruder is pretty unique: Instead of using a hobbed bolt on one side and some sort of spring-loaded lever on the other, it has two drive elements, one on each side of the filament, and they’re linked up with an actual spur gear on each end. One side is driven by the geared stepper motor, the other has a needle bearing inside and is driven only through that spur gear. So you might wonder, if it doesn’t have a spring-loaded lever, how does it grip on to the filament? And that’s pretty simple: It basically brute-forces the filament through the gears, and that works surprisingly well. You can adjust the gap between the gears with two grub screws that press the undriven side against the driven one, and while that’s clearly not meant to be adjusted continuously, it’s also not particularly picky about how exactly you set it. So as long as you use filament that all has somewhat good diameter tolerances, you should be golden. Softer and specialty filaments might need some adjustment as they need to be compressed more than ABS or PLA for the drive gears to grip well.
So one of the main advantage of having a two-sided filament drive is that you get twice the drive force before the extruder starts to strip out the filament. Of course, that doesn’t actually increase the force before the motor starts skipping / since the internal gearbox only gears it down about as much as a Wade’s Extruder does, but it’s still enough to absolutely annihilate anything that stands in its way. In fact, before it starts stripping the filament or skipping steps, the filament will kink and bend either / before or in the bowden tube. And that’s quite a testament on its own – Finally, an extruder that’s stronger than your filament. In my testing, it did allow me to print about 50% faster compared to my Wade’s extruder with an E3D Volcano, which is the hotend, i found, takes # the most force to drive since you’re just shoving so much plastic though it so quickly. Compared to a simpler, non-geared extruder that 50% advantage of the Bondtech might quickly turn into a 200% increase in driving force, but that’s mostly due to the extra gearing.
Now sadly, other than pure strength, the Bondtech extruder is pretty much / a one-trick pony. For example, the way it is built makes it impossible to mount to the standard RepRap hole pattern, which is two M4 mounting holes and the hotend mount dead center in between them. It does have an E3D compatible groove mount and, in any orientation, it does allow you to either screw it to an aluminum profile through the mount piece / or screw # into the mount piece from the opposite side, but, again, neither of those are straight drop-in options for using it as a non-bowden, direct-type extruder, so you’re limited to using it as a bowden with all the advantages and disadvantages that brings with it, unless, of course, you design or modify your printer to specifically fit the Bondtech extruder. And using it as a Bowden brings an additional hiccup along with it: Since you don’t get any kind of quick release for relaxing the grip on the filament, when you want to use a new spool of filament, you’re left with two choices: either) unscrew the adjustment screws far enough that you can # pull the filament out and # push the new one in or) reverse the extruder until the filament makes it past the gears and then let it push the new filament all the back in. Which can take a while.
And the last # big issue i’m having with it is simply the price. The Bondtech extruder clocks in at a whopping 181 US dollars, and mind you, that doesn’t include the Bowden adapter, which adds another 10 dollars to your shopping basket. And, i mean, i see why it is so expensive, that’s not the problem here, i mean, look at it, the drive gears are just perfectly machined and even hardened, so they will last # forever. The housing is SLS 3D printed, so laser sintered Nylon, and that alone probably al#ready makes up for a significant part of the cost, and last but not least, all the little things like the threaded inserts, the bearing and the stepper motor itself show that this isn’t engineered as super-low-budget extruder. What i do have a problem with here is that, at least for me personally, and probably also for the very vast majority of users, the Bondtech does not actually add any extra value. Yeah, it works, but so does my more than five year old Greg’s Wade’s extruder. Never skips a beat and it’s still using that same hobbed bolt i made back then with a cordless drill and a worn out tap. Probably cost me 25 bucks for the entire extruder.
But even all the super simple extruders that are based on WhosaWhatsis’ design with just a single lever, which has quickly become the standard for anything from Printrbots to the MendelMax, those work super reliably, too. They do lose out to the Bondtech when it comes to high-speed printing with something like an E3D volcano, but, again, they still work perfectly fine for day to day printing with a normal hotend and the common materials.
So it all comes down to whether or not you really need that last extra bit of extruding force and how much you’re willing to give up for it. If you want the absolute strongest extruder you can possibly buy, then by all means, the Bondtech extruder is absolutely what you want. But if you’re going for something that’s a bit more balanced and does everything # else # and it’s actual job kinda well # enough, then you’re probably better off with a simpler, spring-loaded type.
So that’s my opinion on the current Bondtech Extruder, it’s certainly an interesting concept, and, maybe a future revision of the design will iron out a few flaws of the current one. If you want kinda the same thing grip-wise, but don’t care about the motor gearing too much, check out Printbot’s gear head extruder, which uses the same two-side-spur-gear approach, but adds a spring-loaded lever, but not the gear box on the stepper.
Thanks for watching, like, dislike, share this video, whatever you feel like, maybe subscribe, but i don’t know if that’s asking too much. Anyways, see ya!
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