TAZ 4 Z axis not lowering

I’ve recently purchased a TAZ 4 from an acquaintance. At the time of purchase, everything was working fine.

I’m pretty much completely new to this end of 3D printing. (IE I’ve prepared lots of models and had them printed, but never used the hardware myself) so I’m pretty much lost in the woods on this.

Since stuff shifted during transportation, I’ve been trying to set the home position using Printrun with Pronterface.

The X and Y axis works fine. The Z axis would not lower below the point it was set at when I received it, about 6" above the bed. When trying to home Z, It moves to this point and begins humming loudly until the machine is shut off. Manual movements in Printrun will go to this point and stop, without the humming.

Manual movements in Printrun will move up, and then back down without issues, just not beyond this point.

I read a post about similar problems https://forum.lulzbot.com/t/z-axis-stuck/1180/1 and followed this advice.
From the new bottom position there, I could manually move up and down with Printrun without issues, but once I attempted to home the Z axis, the exact same problem arose.

These same problems arise when using the GLCD, so I don’t think Printrun is to blame.

As far as I know, there was no damage in transporting the printer, and everything moved fine when I turned the rods by hand, so I don’t’ think its a bind in the hardware.

Any ideas on how to fix this?

It may be a loose or disconnected endstop wire or a loose z motor wire. Check the fittings at all connection points and the board using the ohai kit pictures as guidelines for reference. It shouldn’t be a fuse because the x and y wouldn’t be working.

It could also be the com port speed value in printrun but since the LCD isn’t working right either that’s unlikely.

Also check the x axis for level. Measure from the. Top of the bottom z motor mount leadscrew ball bearing to the underside of the leadscrew nut. That distance should be identical on both sides. If it is off, the z motion can bind.

A longshot, but also check the couple setscrews on both sides.

There are red shipping clamps that may be in place on the z rods that need to be removed before use, check to see if those got reinstalled.

If your X carriage can not travel down in Z travel until you hit the Z limit switch, you have binding issues. The frame may have got twisted, so check it for square top to bottom, and front to back on both sides. It may also have slipped on the X rods and twisted closer or farther apart on the X carriage. Which makes the bearings on the Z rods bind. Manually turn both rods and see if you can lower the carriage until you hear the Z switch click. If the movement is hard to turn you are binding.

Hi I was wondering if solved your problem and how. I have the exact same issue !