Z motor G code

[sjk]

I'm trying to find out why my i3 printer has started to misbehave following a problem where Repetier host froze leaving the nozzle hot and embedded in a print. At the start of a new print the Z motors screech and don't necessarily move to the same height. The code always starts:

...
11 M201 X9000 Y9000 Z500 E10000 ; sets maximum accelerations, mm/sec^2
12 M203 X500 Y500 Z12 E120 ; sets maximum feedrates, mm/sec
13 M204 P1500 R1500 T1500 ; sets acceleration (P, T) and retract acceleration (R), mm/sec^2
14 M205 X10.00 Y10.00 Z0.20 E2.50 ; sets the jerk limits, mm/sec
15 M205 S0 T0 ; sets the minimum extruding and travel feed rate, mm/sec
16 M107
17
18 G28 ; home all axes
19 G1 Z5 F5000 ; lift nozzle
...

(I've removed the temperature settings so I can test easily)

The problem is at line 19. The lift is very fast (5000) even though line 12 says the max is 12. Is one of them in mm/s and one in mm/min?

If I set the line 19 value to a small value, everything works fine but of course I can only do that by manually modifying every gcode I produce. And in any case, there wasn't a problem till just a few days ago.
Any ideas?

I have checked the Z motor voltage and it's 1.17V

[arronwan]

thanks this helped a lot

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