Z axis disables when printing second part

I have an issue after changing the lead screw. It prints great until it comes to the second part. The first part it prints well (set up in cura as one at a time). However, when the second part prints, the printer sets itself to the 0.2mm layer height but does not move down (sits at around 10mm above build surface). It prints in the air. The z axis also disables. While painting I can turn the lead screw as if it is disabled.

2mm lead, lead screw
MKS GEN L main board TMC2208 stepper drivers (LV8729 for extruder)
E3D V6 hotend
Marlin 1.1.8 now, tried 3 different Marlin version.

I am open to any ideas. If I need to post in a different area, please let me know as well.

Thanks

generate some small test code... two * 10x10x0.4 cubes (2 * layer height)

examine the generated gcode.

I suspect its a slicer issue.

Edited 1 time(s). Last edit at 01/09/2019 12:48AM by Dust.

I attached the G-Code that I created. I analized it and it looks ok. However when I try to print it the second square prints around 15mm with the z-axis disabled. I do not see any issues with the G-Code that is obvious.

agreed.

G0 F7200 X222.822 Y146.569 Z5.4
G0 X100.964 Y145
M140 S70
M105
M190 S70
M140 S70
M105
M190 S70
;LAYER_COUNT:3
;LAYER:0
M205 X20 Y20
G0 X94.094 Y134.933 Z0.2
M205 X11 Y11
;TYPEKIRT
G1 F3600 E38.78022

the code between to two objects looks clean

try it manually without all the temperature stuff and manually do this
does it move Z back to 0.2?

G0 F7200 Z5.4
G0 Z0.2

That reproduced the probablem. I decreased the speed to 1000 and it does it just fine. So when it tries to hit that speed it disables the motor. So would I fix that in firmware or in a slicer setting?

your max feed rate in firmware is to high

eg
#define DEFAULT_MAX_FEEDRATE { 300, 300, 5, 25 }

This is { X,Y,Z,E } values

the value 5 sets the max feed rate for the z axis in this example.
This is in mm/s to convert to feed rates which are in mm/minute multiply it by 60

You say a feed rate of 1000 works fine, 1000/60 = 16 (rounded down)
so try 16 for Z max feedrate

Edited 2 time(s). Last edit at 01/09/2019 11:04PM by Dust.

Problem fixed. Beautiful prints. Thank you very much for the help!