Tarantula Belt Driven Z axis

thingiverse

A simple and inexpensive way to get perfect prints, first time, any time ! Forget useless printed brackets and dual lead screws : a belt driven system is the way to go, definitely. BOM : 1x GT2 20T pulley 1x GT2 20T idler pulley 1x GT2 80T belt loop 1m GT2 6mm belt 1x M5*30mm Hex screw 3x M5 grover washers 1x M5 Nylstop nut 2x MF105 bearings 1x 6mm bronze spacer (or a stack of washers) 4x M3*10mm DIN912* 8x M4*10mm button head hex screws* 8x M4 T-nuts for 2020 6mm aluminum profile* 1x Nema17 motor (17hs4401 recommended)* (*)Reclaimed from outdated Tarantula z-axis and extra spare parts in the kit Assembly video : https://youtu.be/IgWcZoRDe20 The mounting for the E3D Titan + V6 + 5015 fan can be found here : https://www.thingiverse.com/thing:2624164 June 3th 2018 : I recently had a talk with a maker who experienced a small fall of the gantry at the end of the printing sequence. Here was my answer : "When the holding current of the Z motor is turned off, the gantry overall weight exceed the motor's rotor inertial and there's a little fall of the gantry. I experienced the same thing when I upgraded my printer to a heavier direct drive feeder. I could live with that, but as long as I had one on the shelf, I upgraded my Z motor to a longer motor (17HS8401) and the rotor inertia was sufficient to hold the whole gantry weight. If you don't want to spend 13€ on a new motor, another solution could be to estimate the 'release distance' (4 millimeters here) and insert a Z raise into your gcode end sequence before releasing the holding current (M18 command). A way to avoid definitely the problem should be to use a larger ratio on the belt reduction. BUT, you can't figure out what kind of motor should be behind the system. Considering the smallest motors should lead to some huge printed parts, longer closed loop belt and a much slower Z axis speed... By the way I dunno if I would do the upgrade for a 100 or 150mm belt pulley at the top of my printer. " Long story short : the design of this belt driven system, the main goal was to provide enough precision to be able to print thinner layers without slowing down the operation compared to a screw drive. The holding torque was considered to securely exceed the gantry weight in operation with the motor provided in the Tevo's kit (My kit is a HE3D's with same motors and manual). Note : the fall only occurs on some printers (upgraded gantries, not so tight wheels...) when motors are turned off at the end of a print, and does not affect prints, even in longer print time. I completed huge and complex 43h print with no issue. June 24th 2018 : I'm glad manufacturers like LULZBOT actually implement Belt Driven Z Axis on their machines (Cf. LULZBOT Mini 2). IMHO you may find a growing number of printers replacing T8 screws by belt system Z axis because it solves definitely the Z wobble effect and makes the homing sequence much faster. There's two FAQ about this system : first, how can this be any better than screw ? Well, in this price range, the screw and its nut's manufacturing is not as accurate as required. The flexible coupling brings some issue, especially because the screw is not supported both sides. The screw needs to be positioned very accurately, what you can't achieve without machinist measuring tools and a long setup process. There's actually no downside to use a Belt Driven Z Axis. Second, why keeping driving the gantry in one side when one of the most popular upgrade is a screw on both sides ? A gantry positioning issue comes from the guiding system and not from the driving system. When you add a second screw you limit the issue but you don't cure it. When the gantry is properly guided, it's allowed to move only in the Z direction the same way both sides. Definitely. Then who cares about a single driving system ? Remember most of professional metal lathes uses a single screw driving system and are pretty accurate. October 3rd, 2019 : Had a nice comment from a long time user, thanks for the feedback Klaus : "Wanted to say TY again for this mod - i have been using it now for many months, and it is the best mod for the Tarantula i have tried. No Zbanding, absolute perfect print quality on surfaces, and microsteppingworks as well btw :) Did some small changes to use metal gear versions of the gears instead of printed ones, but the basic design is sound and amazingly well executed. " November 19th, 2019 : A friend reported the "falling Z issue". Normally with a medium size Nema 17 motor the problem never happens. I asked him to bring his printer to my home for a complete check. The issue was pretty simple and I did not expected that: the Z belt was not tensioned enough. So if you experience the Z falling issue, please be sure your Z belt is tensioned properly.