Z1 Stepper lagging

[dchristie1a]

Printer Model

Voron 2.4 350x350

Extruder Type

Clockwork 1

Cooling Type

Afterburner

I have a self-sourced Voron 2.4 build. When I move the Z axis, motors Z0, Z2, and Z3 all seem to move together. Z1 seems to take a moment to start moving and pulls the gantry out of alignment. Anyone seen this before or have an idea of what the problem might be? Could it be a bad stepper motor, or is there something in Klipper that needs to be adjusted?

 

[shiftingtech]

to be honest, I find it extremely hard to believe that it's *lagging* exactly. (just because I can't really think HOW that would happen). But if it was moving at a different speed, or a different direction, it might give kinda that impression...

If you mark the position of the gantry in all 4 corners, then ask it to move up 25mm. how far does each move?

 

[dchristie1a]

I agree, I don't know how a stepper motor may "lag" the others (thus why I am checking with this group!) Anyway, taking measurements it looks like the others move 25mm but Z1 only moves 17mm and skews the gantry. If and move another 25mm in the same direction then it moves 25mm, but maintains the relative skew. If I reverse the direction, then it again "lags" and only move part of the distance (again, about 17mm). From this i started to think that the other steppers are dragging it along and the mechanical flex in the gantry is causing the delayed movement.

Following up on that, I ran the gantry up and down 300mm several times and confirmed the behavior, but more importantly checked the temperature of the four Z steppers. Z0, Z2, and Z3 were a little warm at the end, by Z1 was cold. I suspect Z1 is dead and needs replacement. I will first check all the connections and make sure nothing has changed (it was working just fine for several months before, but seems to have stopped working when I went form Octoprint to MainsailOS and upgraded Klipper to the latest earlier this week). If that all checks out, then I will pull the stepper.
I will post what I find.

 

[shiftingtech]

Could well be worth just swapping drivers around, see if the problem moves with the driver then.

 

[argusz]

Sound like a backlash problem.
Werify if the z1 motor belt is proper tensioned, and recheck if the screws that hold the pullies on the motor shaft and in the z1 gearbox are properly tightened.
Do a visual check while you do a z command. Does the motor shaft move in sinc whit its pulley and the other parts in the gearbox or are there parts that lag behind the movements....