Extruder shootout by weightlifting

The feeder mechanism, also called the cold end of the extruder. It is a critical part of every FDM/FFF 3D-Printer. In my experience it can not overcome a PLA jam in an all-metal hot end, even if it is powerful enough to tear apart those pneumatic couplings – but settle with anything less and you’re heading for trouble.

As the maximum print speed of my TronXY X5S started to degrade from a comfortable 80mm/s (0.2mm layer height, 0.6mm nozzle, stock PTFE-lined hot end), I reflected upon what I had used over the years and what was on the market now.

To forestall it: The connector at the stepper motor had loosened and started to get hot, thereby limiting power to the motor. The “B’Struder: Universal Bowden 1.75mm Extruder by tempo502” still is a great design for a direct drive (meaning “ungeared” here) bowden extruder. Even if used with a deprecated Mk7 drive gear (Airtripper compared it in 2013 to the Mk8 and found it to be inferior).


The contenders

As already described in [1] the stock chinese Mk8 feeder from the X5S kit did not work on my specimen. And I already had the B’Struder lying around – ready to use and equipped with a 17HS19-1684S from Think3DPrint3D. I used that steppers on my RoStrap and Junkstrap and they have a bit more grunt than the ones TronXY delivered with the kit.

On the Sumpod I had a “Geared extruder by RomanST” (the one that broke the bowden tube coupling) and the spare parts, v3 of it, still were there. The bowden installation is described in [2], the temporary “direct by zip tie” installation (here “direct” means “non-bowden”) in [3].

Then there was the enourmous and much too complicated “Dual Drive Bowden Extruder by invent3d“, used on the Junkstrap with personally dremeled drive gears – as it was designed for 3mm filament. (According to Dyze Design nobody really needs to use that.)

While I gathered all these feeders, the chinese finally cloned some of the latest Bondtech dual drive gears, specifically those Josef Prusa designed into his i3Mk3. I am a big fan of both designers, but sorry guys: The gears were at 60,-€ per pair (before the chinese cloned them) and I totally prefer “XY-Head/Z-Bed” printers.

So I ordered some “Cloned Btech Dual Gears DIY” from the “FYSETC Official Store” on aliexpress and went into vacation. When I got back, I tinkered a bit with them, before finally deciding to adapt Jo Prusa’s design to the X5S carriage.

The description of the recent upgrades in the forum were already tempting and the detailed explanation of the upgrade process made it easy to understand every aspect of the design.

Before you head over to Tinkercad, to check what I came up with, I have to dampen your hopes: I also adapted the design to my old E3Dv5. 😛 And it can take some time, ’till I blog about this, because it was quite a bit fiddly and I don’t consider it completely done yet.

Enough prelude – what happend!?

My old RAMPS / PC PSU combination [4] did the job of driving the motor. It was still configured for the Junkstrap’s Z axis, but I just tuned the manually entered Gcode for a common “cable winch” test with what I found to be heavy. Lacquered break pads I use as paperweights, mostly.

Now for the comparison:

The enormous Dual Drive extruder spectacularly…

It could lift a mere 254 grams, before starting to skip steps. A rechargeable AA cell more was too much. How could that thing work at all in the Junkstrap!?


The B’Struder on the other hand flawlessly lifted 1.432 kg – and I was nearly carried away to say “That’s all the force you need!”, until the other two showed off. 😉

The spare “Roman_ST” design, printed in ABS on the Sumpod and still utilizing a spring that brutally squashes the filament oval, lifted a whopping 1.971 kg!
Because I couldn’t add more in this setup. 😲 (The bucket tilted.)


Would I go back to that Mk7 drive gear, outdated in 2013, and printed gears then?

No. The modified, self printed Prusa design with the china clone wheels impressed me otherwise. It lifted 1.856 kg without any gear reduction. And those gears grip the filament from both sides – so my educated guess is, that this setup will be more reliable at the end of the day.



[1] Tronxy X5S: Heatbed and Movement

[2] Sumpod Extruder Upgrade

[3] JunkStrap’s Extruder

[4] Junk electronics, new electronics


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