Taz 6 Auto Leveling Knocking

Hi all,

I’ve had my Taz 6 for a couple years now and after a recent firmware update, during the leveling process, when the nozzle touches the corner pads, my machine makes some loud knocking sounds. https://photos.app.goo.gl/suqEzncnYbf2xGDL6

Any ideas what this could be?

This looks normal to me. After a certain firmware version they started doing this. Looks like micro stepping for the auto leveling, slow and close to get an accurate reading so it can do its leveling algorithms based on each corner’s reading. I think it sounds loud because you’re in a room with nothing to absorb sound so the sound is bouncing, amplifying and echoing.

Ah ok. I was worried that something had gone wrong with it. Thanks for the response!

The “knocking” is the backlash measurement. If you look closely, you can see the Z stepper motors moving one step at a time raising the nozzle until the electrical connection breaks.

From the video, it sounds like you have a lot more backlash in your TAZ 6 than I have in mine.

Would that be a good or bad thing, having more backlash? Should I manually turn the Z screws to try and adjust it?

Without a way to compensate, less backlash is better. With a way to compensate, it doesn’t matter.

No, you can’t adjust it this way.

Google “mechanical backlash” for a lot more detail. Basically, when you change directions, there is some small amount of error in the actual position vs. the desired position. If you know what this error is, you can adjust for it.

On a TAZ 6, the X & Y backlash are assumed to be very small. Older versions of Marlin assumed that the Z backlash was also very small and mostly got away with it (because for most of the print, Z was always moving in the same direction).

Versions of Marlin with backlash compensation (M425) can measure and adjust for it and at this point, it doesn’t matter how much you have.

My TAZ 5 steppers started knocking after Marlin 2.0 during leveling and printing. I turned down the digipot motor current and my printer works just fine now.