Solved Z-sensing component falls behind other Z pieces, causing bizarre layer height issues

Pictures, because it's hard to grasp what I'm talking about without seeing it. Notice how it's normal at the bottom, then gets stretched further and further in the middle, and then goes back to normal again at the top.
At first I thought this was an issue with Z increments, but the fact that the top went back to normal obviously discounts that.

Once I noticed that the part of the threaded rod that lifts the left side of the extruder carriage (and that has the Z sensor) had actually slipped out from underneath while the rest of the carriage was supported solely by the components on the right side, I realized what I think the problem is: The sensor is no longer being pressed, so the printer assumes that it's at the bed, and therefore it will not make any Z-downward motions.

That means that every time there's a Z-hop (printing with PETG has made that a necessity to avoid stringing), it goes up but doesn't come back down - so the sections with the most isolated print spots end up being taller than the rest.

How on earth could this happen? Could the Z stepper motors somehow be misaligned, or could the threading in the Z-sensing component be worn, or could it be something else? I have no idea how to troubleshoot an issue like this.

This is the Robo 3D R1 with the original threaded rods. This only started recently, after I had to move the machine around and upside down to make some fixes and unrelated mods. I also updated to the latest version of Marlin that is listed in the Mods & Upgrades subforum.

It seems like every time I fix something on this printer, a much worse issue takes its place. I'm getting increasingly fed up with trying to make this printer cooperate, because I have not been able to get a single quality print yet. Any help would be greatly appreciated...

 

I don’t have it on hand right now so I won’t be able to take a closer look until later today, but based on a conversation you had with me in another thread, it sounds like I have the non-Beta, non-Plus version.

I know that the right side has two wires coming out of it like the left, but I haven’t noticed it making the same “clicking” sound that the left does when the carriage touches or separates from it.


Sent from my iPhone using Tapatalk

 

How would I do that?


Sent from my iPhone using Tapatalk

 

I'll give this a try once I can and update with the results. I'll also take a closer look at that right side - like I said, I see the wires, but the clicking only ever comes from the left side.

 

Right, so I'm assuming that the left side being separated leads to that. The question is how it could even get to that point, since due to the way it's connected to the rod and the carriage, the only way that seems possible to me is for the left stepper motor to be rotating slightly more slowly than the right - or, alternatively, by the right stepper motor failing to rotate in the opposite direction when the Z needs to go down.

Hopefully that's a simple firmware issue that will be resolved when I go back to the official release version.

 

Looks like the wrong Z-Steps for your machine to me

 

Restoring the firmware fixed it! Thanks.

 

Where the print starts getting messy there is not much cross sectional area. I've done prints like that and the plastic was still too hot when it did the next layer causing similar appearance. This could account for why it started getting better when it got to the top (more cross sectional area to print). Solution? Delay printer between layers? Change model to have more cross sectional area? Make features thicker? Add dummy section off to the side? Print multiple parts at once?

Sent from my SM-S320VL using Tapatalk