I am on the way to building my own printer using 2020 profiles, TR8 * 500mm lead screw for the Z-axis. Still thinking if that will be a h-bot or coreXY, but this is another story.

As the printing table shall be mounted in a stable condition I am using this Tevo TornadoCube transformation as a base for the Z-axis. The guys are using metal housing for the lead-screws, but I am wondering if I just print this housing, lead screw mount, from thingiverse and add a 608 bearing - would that be acceptable?


As per Oscar's comment, my bed will have a set of linear guides next to the lead screw, for stabilization.

This is also a nice solution for the Z-axis. In that case, I have same question: Can I print bearing housing and rely on it, or it is better to use metal ones?

  • $\begingroup$ No linear rails to guide the platform, just 3 leadscrews? (With all their wobble and imperfections!) It is better to separate movement from guidance so you don't constrain the leadscrews at the top and bottom, one should be left free. $\endgroup$ – 0scar Apr 16 '18 at 13:02
  • $\begingroup$ @0scar this is my entry point, so added update to my question. $\endgroup$ – profesor79 Apr 16 '18 at 13:28
  • $\begingroup$ I recently went through a similar upgrade. From Anet A8 to Ultimaker 3 extended to CoreXY (HyperCube Evolution). All parts of the HyperCube are printed parts, I tried both PLA and PETG and found that these are stiff and strong enough to hold the linear rails and the leadscrew (steppers and plum couplings). Print quality is similar to the Ultimaker. $\endgroup$ – 0scar Apr 16 '18 at 13:38
  • $\begingroup$ @profesor79 I´m printing a whole CNC which includes lead screw guide and shaft supports in order to achieve a smooth and quiet moving. The bearing 608zz is the correct size since the inner diameter is 8mm for an acme thread. 607zz has 7mm as inner diameter so for this you will need an std thread. $\endgroup$ – Fernando Baltazar Apr 18 '18 at 5:17
  • $\begingroup$ Shouldn't @Oscar comment be upgraded to be an answer? $\endgroup$ – cmm Apr 20 '18 at 20:45

To answer your question, you could use either metal ones or printed ones. Metal housings are way more heavy that printed parts. The housing you refer to is not attached to the platform, but a static part connected to the frame. Weight is not an issue, stiffnes, strength and temperature stability should be of higher importance.

For metal housings attached to the Z platform weight may be an issue (if have many microsteps where the incremental torque may not be enough to raise the Z platform). Printed parts can be made stiff enough to house the linear bearings. In my experience printed bearing housings can be just as effective, I use those on my platform for my CoreXY printer as well as using leadscrew and linear guide rails brackets made of printed parts.

Old answer, before question update:
With platform movement (or printer head Z movement for Prusa designs) you face a few challenges related to the quality of the parts you buy. Note you want smooth operation of the platform (or head) without wobbling. It is customary to add linear rods or rails to guide the platform up and down, this is their sole purpose, therefore these rods need to be very straight and bought from a local trustworthy vendor (the Eastern oversea specimens are usually of less quality as I know from experience). Securing these linear guide rods could be done with printed parts, the plastic is stiff enough to hold the rods in place, and temperatures are usually not that high to play a large role (if so like in boxed up printers, print in high temperature resistance material), personally I use black PETG.

Secondly, the drive of the platform. Note that leadscrews are not perfectly round, nor is the coupling 100% in the center of the screw. From a mechanics point of view you should never constrain the leadscrews at both ends. This results in an over-constrained (indeterminate) system (of forces) that can induce even more problems. Optimally you fix one end close to the stepper, or the drive of the belt), it is arbitrary whether you use a metal or a plastic part for that unless there are constrains on size and thickness for a requested rigidity and leave the opposite side free. For Prusa clones I use lifting parts that house the lead screw nut rather than embedding the nut in the x-y idler coupler (this separates eccentric x-y movement from z movement and a handy advantage is that if something goes wrong in z min direction, the head will not destroy the glass or bed as it is not fixed to the lead screws). Something similar can be done for your platform. For my CoreXY however, I have not done so, it uses 4 linear rails of 12 mm and 2 leadscrews. PETG stepper mounts at the bottom drive the leadscrews using plum, not spring, couplers (the springy types should be avoided or a ("fixate-able") bearing or KFL08 mount should be placed at the other side of the driven side of the coupler and correctly mounted to the frame). Furthermore, I use Delrin or POM anti backlash nuts on a mount connected to the platform. All tall prints I make are perfectly straight, no wavy or wobbly vertical walls.

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