Add Dual Z Stability!

Improved Z axis stability on Fokoos Odin-5 F3. Dual lead screws often fall out of sync when powered down, moved. Often bed tramming is used to correct, but unless lead screw sync corrected, gantry may bind over time.

Adding synchronous pulleys and belt to lead screw tops is a low cost solution. Except for simple 3D printed idler tensioner mounts, other parts are readily available. I can share stl mount, but not sure how to do that.
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V-feature on bracket keeps bracket parallel to extrusion and keeps top and bottom ears from collapsing towards idler with screw compression.
Idler shaft hole is closed on bottom of bracket. Bracket installed, then pulley inserted and shaft finger pressed in.

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A test for lead screw stability starts with using a sharpie to add index markers on lead screw couplers. Use of printer a few times, including power off, for a few time. If index lines migrate, then you have proof sync issue.

To assemble sync belt addition, top bearing mounts are removed to install pulleys and belt. Loosely install the mounts, raise Z carefully near top, then carefully align and tighten mounts pulleys and idlers. It is important that lead screws are straight, zip-tie restraint during shipping can bend lead screws. An easy test is see if upper bearing wobbles when hold down screws are loose.

The belt used is a 2GT-606T-6. It is more common and less expensive than a 605T. It may be possible to omit one or both tensioners, with a 605T, but have not purchased one to try.

I also changed from bed springs to silicone mounts. Both changes have lead to easy and stable bed tramming.

Excellent idea. This was always one of my concerns with the Fokoos Odin-5 F3. A bit higher-end machines such as the Ender 3 S1 and S1 Pro ship with belts already in place. The Prusa Mk3 uses a different approach. They have a firmware function to move both axes all the way down to force synchronization and they relied on feedback from the stepper drivers to determine when they hit the bottom. I am testing the S1 Pro right now and I think the Prusa MK3 is going to have some real competition at a much lower price point. The new high-temperature extruder is quite nice.

Yes, the JG Maker Artist D also comes with top mounted sync belt. It uses a single tensioning idler. Too bad the extruders can’t handle PETG.