Central Z drive (Tevo Tornado, CR-10)

thingiverse

**Update March 30,2020** I fiddled around with this design and found it had two major flaws: - Your lead screw and nut need to be top-notch quality. Unfortunately, my parts were not up to par; while printing the top piece for a standard nut, I encountered the second issue: - Your Z lead screw coupler needs an exceptional grip; unfortunately (yet again), this conflicts with the otherwise excellent printed coupler (https://www.thingiverse.com/thing:602481). Mid-print, the coupler slid off my motor and the entire gantry crashed onto the print bed. I also wouldn't trust those original spiral couplers (they'll be pulled apart on the medium to long run). The Z Axis design has always bothered me in my Tornado - raising a long bar on one end doesn't seem like a solid solution to me. There are many designs addressing this by implementing a second lead screw. This, however, comes with some downsides for me; the most significant was that I wouldn't be able to use rear Z-Brackets anymore (I haven't implemented them yet, but the possibility of doing so is important to me). Again, there's a design incorporating Z-Brackets, but after a year of thinking, I realized I don't like the idea of being bound to this one and only implementation. Plus, these designs have a tooth belt at the top of the printer, limiting largely top-mounted equipment like spool holders. This particular design is based on the description a user "PetersHobby" posted in the German Tornado group on Facebook; please credit him for the original idea! My changes were some improvements: I utilized the V-Slot of our printers, so that the motor holder and the nut holder now fit the slot and therefore are attached even more stably (important especially for the motor holder, which will experience varying torque because of the hotend moving from left to right). Additionally, I altered the lead nut holder to fit the nut I have. What you'll need: - Lead screw (you can probably use the original one, but I went with [this][ls]. 500mm length should be sufficient; I'll update the exact length once I've cut my lead screw. [ls]: https://www.motedis.com/shop/Dynamik-Lineareinheiten/Trapezgewindespindel-Zubehoer/Trapezgewindespindel/Stahl-Trapezgewindespindel/Trapezgewindespindel-RPTS-rechts-TR-8x15-L%3D1000mm::3953.html - Lead screw nut (I'll upload a file for the original nut in the next days), I went with [this][ls] one. [ls]: https://www.motedis.com/shop/Dynamik-Lineareinheiten/Trapezgewindespindel-Zubehoer/Trapezgewindespindel/Stahl-Trapezgewindespindel/Trapezgewindespindel-RPTS-rechts-TR-8x15-L%3D1000mm::3953.html - Depending on the control box location, you might need an extension or a replacement for the motor cable. Printing works without supports (with the correct orientation, of course). I strongly recommend using at least PETG and 50% or more infill, as these are structural parts carrying significant weight. Attaching the upper part might be tricky, but I urge you to use all 7 screw holes, since this part will be carrying everything. Also, while it's not absolutely important to center the parts, you need to make sure they're aligned vertically. Misaligning them can break these printed parts because of the forces which will be tensing them. The holes for the M3 screws in the upper part are a bit too small; that's intentional. You'll need to drill them with a 2.5mm drill and then tap the lead. I don't recommend not tapping at all, as the holes are too long for self-tapping. The 3mm holes in the bottom are also too tight; you'll need to use a drill (matching your screws) to get an M3 screw through them. Make sure to use the correct drill - these four screws will carry the weight of the Z-gantry, including the hotend. I recommend using a washer under the screw heads - the motor can get quite warm and the screw heads might get warm too. Warm metal screwheads could force their way through the plastics...A washer helps to reduce this effect chance.