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stev-20
(@stev-20)
New Member
Gcode ordering curiosity

I am trying to trace a problem with my printer that has caused me to look at the Gcode produced by PrussaSlicer.

M203 sets maximum feed rates in the 'current units' but I see this line always precedes G21 which sets the units to mm.  I don't think this is the cause of my Z lift problem but it does seem odd.  Does anyone have an explanation?

Posted : 06/08/2020 8:41 am
Neophyl
(@neophyl)
Illustrious Member
RE: Gcode ordering curiosity

What do you have in your Printers Start Gcode in Printer Settings ?

Posted : 06/08/2020 11:18 am
stev-20
(@stev-20)
New Member
Topic starter answered:
RE: Gcode ordering curiosity

@neophyl

Hi neophyl,

Thanks for your input. I realise I didn't explain why I was asking about the relative positions of the lines of Gcode -  I often get a screech of Z motors at the start of a print, wrong Z positions and a print that is obviously going to fail. I was suspicious of the  line "G1 Z5 5000" which you have identified as coming from the Start Gcode.

 I wondered why the print always started by lifting (or trying to lift) the nozzle.

The start G code was :

G28 ; home all axes
G1 Z5 F5000 ; lift nozzle

I'm going to insert G21 before this and drop the speed to F500, even though the earlier M203 should have dealt with the unreasonably high speed.

I certainly haven't changed the 'Start Gcode' section so I don't know why it is misbehaving now (after at least a couple of years of proper operation) and why sometimes it still works fine

Posted : 06/08/2020 5:37 pm
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