Remixed Nema 8 Adapter for Zesty Nimble V1

thingiverse

UPDATED w/ V3 (details below) The Nimble's a super light and super awesome direct drive extruder but what often goes unmentioned is that you also need to account for the weight and potential resonant vibrations from the drive cable. Wouldn't it be great to ditch the cable in favor of the lightest stepper motor that Nema makes? Well guess what? You can! This is a remix of ZestyTech's experimental adapter geometry. That geometry was used as inspiration but it doesn't have quite enough tolerances to allow the shaft and mount to work on the Nema 8 that I bought so I redid the mount from scratch in Fusion 360. I've included both the STL and the Fusion 360 file. The nice thing about the f3z file is that it's fully parameterized so it can easily be tweaked to fit your own needs. It could even be tweaked to fit a larger stepper motor if you wanted to. Do be aware that the Nema 8 doesn't have nearly as much torque as a Nema 17. Thanks to the Nimble's 30:1 gear ratio, it still works just fine but it will run a little hot. On my modified Ender 3 Pro, it's topping out at around 55c, which is well below the rated temperature rise of 80c. (Those heat sinks in the photo almost certainly are not necessary but they're light enough that I figured it wouldn't hurt.) If you think you're going to be pushing more difficult filament that needs a little extra torque, you may want to consider using the slightly longer 0.6A Nema 8 in favor of the ultra-light 0.2A Nema 8. The 0.6A has about 2.5x the torque. I've tried both and I think the added torque of the longer Nema 8 is worth the additional 20 grams or so. Note that I've only included a left-handed model. If your Nimble is mounted in the right hand orientation, just mirror the STL in your slicer. You'll also need one of the shaft models which you can get from the original thing that this remixes. I printed mine horizontally in PETG and it seems to hold up to the stresses just fine but you may want to print a few spares just in case. I do NOT recommend printing the shafts in PLA or ABS as they will likely fail from the stress. PETG has just enough flex and give that it should continue to hold up. V3 UPDATE I've modified the original mount to better accommodate M2x4mm screws and washers. I've also tweaked the stabilization arm so as not to obstruct one of the mounting screws. This makes it easier to assemble. I've also added a small filament guide which can be attached onto the top of the Nema 8 by backing out one of the case screws and then using the case screw to attach the filament guide. The clip on the guide is sized so as to accommodate a small length of Capricorn PTFE tubing (it should snap right in) but you could just as easily leave it out if you want. This should help with keeping the filament off your warm stepper motor and (as you can see) it works with either size Nema motor.