Review on WINSINN Dual Gear Extruder, Compatible With Ender 3 CR10 CR-10 Pro CR-10S Tornado Upgraded Aluminum Drive Feed For 3D Printer 1.75Mm Filament (Dual Connector) by Tom Tucker

This is specifically for the Dual-Gear extruder upgrade for the Creality line of 3D Printers. I'm using this for Ender3's and have friends who also have used this on Ender3 and CR-10 printers.All and all, I love this upgrade for a number of reasons:1) Much more consistent flow-rate than the traditional idler-wheel extruder design2) Works great with flexible filaments like NinjaFlex and other soft TPU/TPE materials3) Pretty much a drop-in replacement for the original extruder body sans for some configuration tweaks (see below) and a particularly annoying lack of qualiity-control in the provided parts (also, see below)Once this is installed, the biggest trick is doing an e-steps/mm calibration update in your firmware. Stock, the Ender3 comes with an e-steps/mm setting of 93-95 steps/mm. Since this extruder's hob-wheels (the parts that actually push the filament) are a much smaller diameter than the stock extruder's hob-wheel, you have to increase the e-steps/mm to get back to consistent flow. There's a great YouTube video by the vlogger/maker CHEP that explains this for this very extruder, just search for that.When all was said and done, the new range across 3 printers has been 142-145 e-steps/mm. You'll also want to do some line-width/flow-rate tests and retraction calibrations too as this definitely changed my behaviors for the "better" with both of those results.Now. about quality control.Between two friends and myself, we purchased 6 units of the Dual-Gear Extruder for upgrades to our respective printers. Of the six units we received, only two had all of the parts and correct parts for building the extruder. The other four had one or a combination of these problems:1) Missing needle bearings in the idler gear/hob-wheel - Two of them had this issue. this part is supposed to have two stacked need bearing cartridges. We received two units that only had one of the bearing cartridges making the idler sloppy/jam.2) Grub-screw for the motor-shaft-mounted gear/hob-wheel was two long - Two different units had this problem, which ends up jamming up the extruder. Basically the grub-screw needs to be very low-profile. only about 2mm tall in order to clear hitting the other gear/hob-wheel. In the case of the bad units, the grub-screw was about 3mm and stuck out of the gear/hob-wheel causing it to bump into the other wheel during rotation and effectively either lose compression on the filament, or jam the stepper.3) Compression springs too long - Two units came with compression springs that were about 4mm too long and couldn't be install even when fully compressed. We replaced these with some shorter sprints we had from another project, but it was also one of those "if we didn't have extras, these would be useless" situations.All told, because we collectively ordered 6 of these to upgrade 4 printers, we had parts to spare and mix-and-match until we had 4 viable units. But that's a 33% QC failure. If not for those issues, this would be a solid 5-star upgrade.Also, even tho this is being marketed for Creality's printers (because they're so popular these days), this will work fine for other bowden setups. I'm actually considering putting one on my HICTOP prusa-i3 clone to replace it's direct-drive unit that's nothing but a maintenance pain with a bowden setup.