Custom Z Lead Screw

It's hard to get a good photo. When you are looking at it in your hands, the banding is a lot better to the point of not being perceivable. It now more looks like x/y backlash than banding on the Z Axis, as what looks like banding on the above photo is only on the corners, the walls have no banding, compared to the old screw that has the sine wave banding repeating every 1.4mm or so. Perhaps I should of printed something cylindrical to compare. This threaded lead screw has a better nut, better threads, and better machined, and has given me markedly improved results.

I really dislike the software fix. It it yet another level of calibration over the top of a machine with a lot of calibration already required. Seems very much a band aid fix to me.

I'm not sure I can really agree that constraining it at the top is bad thing, this new threaded screw is straight, not bent. With the top constrained properly I don't have to worry about the Z coupler compressing.

A few more pictures of the new nut/bed attachment. By shear luck, the shaft of the nut was a press fit into the pre drilled shaft hole in the print bed:

Almost the finished result:

I bet PVC tube/hose would eliminate the rest of those imperfections.

I think it has been observed many times already at this point that flexible coupling can produce better results.  The threaded rod being directly attached to the shaft more easily broadcast the wobble without doubt; a perfect LS/Delrin combo would be machined well enough that you can keep it all rigid...From my research there are really 2  good ways you can handle this problem:  Flexible (like the prusa i3) Rigid (alumantus spelled wrong sry) SD (mixed and bad)...which printer z axis cost the least to reproduce and has the least visible wobbling...yep the i3 with rubber hose couplings.   I have never got around to installing that LS I purchased....I have moved to i3s myself.

Sorry not wishing to steal the tread for yet another wobble fix but this is the latest post I could find near the subject....but I think I found what I was looking for.

I knew I had seen something that "should" mechanically sort all this z axis wobble out, and help with your custom lead screw fitment.

Not exactly cheap but should be worth a try. I like to work with the theory if it costs more than £1 then it had better be worth it.

Caswal if you replace the flex coupling you have with an "oldham coupling" it should remove any issue with Z axis movement and allow the drive rod to wobble but not influence the bed as it is now only being held in the x/y axis by the drive nut so no force can be transferred to the bed.

Any Z axis backlash will still need to be removed by the larger drive nut but that is a given an yet another topic.

I now return you to your normal program........

Haven't had time to really experiment with the Lead Screw as during the week my hot end clogged and caused me a lot of trouble. So this weekend.

I like that coupling ysb, I was going to 3d print a straight coupling myself. The flex coupling is not that bad in the Z axis, so long as you don't use the feature that drops the bed while crossing perimeter. I tested the flex coupling a lot with a dial gauge, and once it has settled down (takes about 0.3mm, which is mostly dialled out in the first layer) you get consistent 0.1mm drops.