Here is a video of Z-Axis misbehaving. I can reproduce this issue reliably every time by doing these steps:
- Power off, position all axes as seen in start of video.
- Power on, bot is at 0,0,0
- Move absolute to -800, 800, 400
- Bot moves as seen in video
- Go back to 0,0,0 (NOT homing, because that makes each axis go individually)
The Z-Axis starts to spaz out when X and Y finish their travel. It looks like Z is missing a lot of steps, causing the Axis to slowly drop down again. When Z starts to decelerate, it picks up again and goes up slightly.
- Bot now thinks it’s at 0,0,0 but it’s more likely to 0,0,250.
Video: https://drive.google.com/file/d/0B8PVEtF0Y5mNQ2F3QUNxVC1JY0k/view?usp=sharing