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Inconsistent Z Movement


New member
Printer Model
Voron 2.4 (300mm)
Extruder Type
Clockwork 1
Cooling Type

I have been using my Voron 2.4 for a few months now and up until recently have been getting pretty good print quality.

I have come across an issue where I am getting inconsistent z movement during printing. A small part I was trying to print was 30.6mm high in CAD. However, when printing towards the front of my bed, it ended up being almost 3mm taller than in the design! Similarly, on the rear side of the bed, the part is still 0.8-1mm larger!

I did some investigating and found the following:
- My bed is pretty level. There doesn't seem to be any issues there.
- I can run a Quad Gantry Level, which levels the gantry very well at a z-height of 1-5mm. However, as I move the gantry higher it begins to tilt. At a z height of 100mm the difference in height between the rear left and front right carriages was almost 10mm!

I am certain that the issue lies with z-belt tension and/or stretching. However, I was wondering if there are any other causes I should be looking into that may be contributing?

At least one of your motors is either not working at all, or is running incorrectly. I would test
1. that all 4 z motors still buzz properly (see the stepper_buzz tests in the startup guide)
2. that all z drive grub screws are tight
3. that all 4 motors have the correct rotation_distance (40) and gear_ratio (80:16) in the config
4. that all 4 motors do indeed have 16T pulleys

you can probably figure out which motors to focus on by the simple process of
1. put the gantry at some height
2. mark the gantry position in all 4 corners
3. run the gantry up a known distance (50mm?)
4. measure how far each corner actually moved.
(focus on the ones that are dramatically wrong)