Z-axis motor binding

I have two TAZ 1/2 (oldest version) printers, I used to run them with RepieterHost and they worked a little poorly, the layering resolution was not the greatest. After changing to the Cura software, problems started to come by. Every time I open a new control window to print an object, after hitting print, all motors re-home and the last one to do so is the Z-motor, but after hitting its limiter it makes a horrible noise, like if was stick or binded to something, forcing the motor. The weird thing is that in only happens for the first try of the printer. After i cancel the print, and reset the temperatures, i hit print again in the same control window and it works just fine.
I already performed a few solutions and non have helped. Lulzbot support suggested me to flash the software in the printers, not successful. I tried loosening the z-carriers bolts and retighten them, not successful. The printers are fully lubricated and clean so i have totally ran out of solutions here. please help me!
thank you in advance!

Are both motors making the bad sound, or just one of them? If you disconnect the threaded rod from the motors entirely does the same thing happen? If you try starting a print with repetierhost again does it now do the same thing?

Binding is generally a persistent issue. It’s either bound and stuck, or it isn’t. This sounds like either an electrical or a software issue. If it was doing it constantly, i’d look at the electrical connections for the motors to see if one of the magnet pairs was shorted out or unhooked, but in this case I suspect that it’s trying to move the motors faster than they want to go, and that maybe there is a bearing failure that only goes away after the motor heats up enough to expand? That or you have Taz 3/4/5 firmware loaded somehow.

Can you post a video of what it is doing by any chance?

both do the noise, and no it will not do the same sound if you do it again in repieter host. I did the “looseing the z axis bolts” trick and it worked for about two prints. after that, the binding will happen again.
I’ll try to do a video and post it as soon as possible.

I’ve made this video https://youtu.be/eCWZoFAvw78 It shows exactly how every print goes. there is a lot of background noise but the weird noise the printer makes is still noticeable and if you notice the second print does not happen to have this z-binding issue. This problem does not happen in repieter host before nor after trying it with Cura. I already tried to loosen the z-axis bolts and also tried reflashing the firmware; none of that has been successful. hopefully if by looking at this video you can get me a better diagnostic

keep in mind that the ties in between the z-rod and the motors were installed after this issue came around, so i do not think they are the problem

Aha! I know exactly what has happened to your printer. One or both of your z axis wobble minimizer printed Springs has failed. Typically there are rwo brass nuts inside each printed w shaped spring, with a metal spring pushing one nut up and away from the printed part, and the lower one pre tensioned and inside the lower socket. The metal spring pushes against the top of the plastic socket the lower nut is in usually. In this case on at least one side I can see, it appears the nut may have punched through the socket lid internally. Both nuts are still in the socket, but they aren’t holding z position correctly. That or they got untensioned somehow. Inspect the plastic spring thing. If you see a section of loose plastic shaped like a hexagon with a hole in it, that’s the problem. If it looks intact, re tension the metal spring by compressing the metal spring as much as you can, then thread the lower nut up towards its socket as much as you can, repeat for the other side.

Im a bit of a rookie with this machine, so i do not know what you mean by lower socket and i dont know how to re-tension the spring?
I revised the W shaped spring parts and i noticed that the brass nut was not inside its designated hexagon-shaped hole where it needs to be, and the metal springs that push it up were not installed.
After identifying that, i inspected the part and it didn not have any major damage, after that i cleaned the z-axis threaded rod and the brass nut with wd-40 and inserted the brass nut where it needs to go and placed the spring into the part.
Unfortunately after doing this, the binding was still there. I contacted lulzbot support and they recommended me to replace the rod and nut becuase the saw in the video that they present wear and that causes de binding. Could this be a solution you would consider? Am i doing anything wrong with the W-shaped spring?

I decided to try to go around the binding issue and try to see how the second attempt at printing would go, and this was the result. It seems like either the z stopped going up and kept extruding or it started going down instead. Any of those two caused the print to fail. But is this related to the original bindig issue?

In your posted video you will see the right side of the X carriage suddenly drops down around 47 seconds in. I think one of your couplers may be slipping.

It dropped because the z carriage nut was not placed into the socket designated for it, when it finally got aligned, it dropped because it went into its right position.