Prusa Z axis, so many problems yet one simple solution !

thingiverse

Note: This has worked perfectly for more than a year and is still valid. However, I wanted to take it further and get rid of all the subpar linear bearings and poor lead screw nuts. Done, I even managed to eliminate the vertical smooth rods, with the lead screws doing the job (although TR10 would be more rigid, TR8 are acceptable) see here: https://www.thingiverse.com/thing:2594693 WARNING: Don't let negative comments fool you. This WORKS ! Unfortunately some people either misunderstand or lack the proper knowledge to grasp it, while others just express anger towards my criticism of their poorly designed "things". Just check what these people published and demonstrated. Some even created accounts, posted nothing but hate speech. PS: Be cautious, as some are scammers, trying to solicit funding or sell their wares. I shut them down ! See the first posts below for such human garbage ! +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ The Prusa configuration is one of the most popular, low-cost, and easy-to-build 3D printers with a few flaws and limitations, but one that's not acceptable as it's easy to fix: two unsynchronized steppers driving a lead screw at each end of the X carriage. To make matters worse, many kits come with regular M5 or M8 threaded rods that are totally unsuitable for the task (often bent !). You can find numerous poor attempts to get rid of the wobble and canted X carriage. Plastic braces trying to constrain the lead screw just reduce it, not eliminate it. Auto bed leveling gimmicks are a waste, often introducing more problems ! And they add weight (except the IR one from DC42, which is the only decent one for the job) ! Note that auto bed leveling is almost a must in non-Cartesian machines, but here it's just a poor attempt at compensating for a poorly designed and assembled machine with cheap, low-quality components ! Better spend your time and money on real solutions. Of course, what I propose isn't the first setup using one motor, two screws with a closed belt and pulleys to drive them but is the simplest I've seen. It should be easy to adapt to other "metal" Prusa variations. I use a 8mm lead screw and three 36 teeth pulleys giving 400 microsteps/mm, 0.04mm per full step, a number I like. As is, the required torque to go up is about 10 N.cm. No big deal for the Nema17 40mm. I've used it for months now. It's a proven solution. I don't recommend it for "acrylic" or other flimsy frames, these may bend with the belt tension unless reinforced and anyway are junk not worth improving. Sell or give them to people you don't like :) No wobble, vibration (all my bearings are of my own) and no need to level the bed anymore unless I make changes to the bed for ex. Now I can print decent parts and why not for a more professional design than the Prusa. I added a version of motor bracket to be able to mount a PM 48 series stepper one can find in many laser printers. You may need an 3mm ID 5mm OD adapter. Torque is plenty enough for a regular Prusa provided there's no binding or the X carriage doesn't weigh like a dead donkey. Note that I reinforced the frame as you can see in the picture. Just two Aluminum profiles, bent plate and bolts, attached to the vertical frame and the M10 threaded rods. Many ways to do it, here are some decent solutions. Must be rigid, avoid flimsy plastic parts, makes them beefy. Then you can bolt the whole printer to a heavy thick (40mm) flat piece of old kitchen table top or anything like that. I even simplified the system by removing the right rod: https://www.thingiverse.com/thing:2504861