Parking laser cut head after etch

Controllers Smoothie
1

Greetings Maker Forum.
I’m experiencing an end of cut issue which will eventually crash the head if it’s not fixed.
The current task is etching on driftwood.
Because of the thickness of the wood the “Z” axis is dropped before starting the etch.
After the etch the “Z” axis moves back to zero position first … before “X & Y” axis begins to move to park position.
The finish sequence needs to change to “park “X & Y” axis” first then move “Z” axis to zero.
I see no option to change the sequence in the Lightburn user interface.
Browsing the LightBurn perfs folder reveals no obvious answer either.
The machine is running Smoothieboard with Cohesion 3D firmware.
Looking over the Smoothieboard config file is not revealing the “finish of cut” sequence.

Anybody have ideas where to look, how to make the change ?

Thanks kindly for your input.

2

It is probably called the Homing sequence. Often it can be defined as all 3 axis at once or one axis at a time. Should be in Smoothie config.

Try:
homing_order XYZ

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3

If it’s homing, then yeah:

Smoothieware endstop docs: endstops [Smoothieware]

image
image883×52 6.55 KB

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4

I guess I need to update my smoothie firmware… My config does not have that option, home_z_first.

5

@PaPaSteve Feel free to paste the last few dozen lines of a gcode file demonstrating the problem here. Put it between lines with exactly only three open single quotes, like this:

```
the gcode goes here
```
6

Home position is set for left front with Z being the last to move in the sequence.
Whereas at the end of etch function the Z axis is first to move to home position then afterwards X,Y axis moves to right rear.
Hadn’t thought about saving the gcode generated in LightBurn … good idea, I’ll look into that in the morning.
THX for your suggestions.

7

Lightburn does have a setting where you tell it you want it to home at the end of the operation.

You could add your own ending gcode which homes X and Y( G0 X0 Y0 ) then on the next line homes Z( G0 Z0 )…

8

Michael
Thanks for the gcode inspection suggestion.
So here’s the last couple lines in a simple circle path.
It is obvious what’s going on.
The software generates a return to “Z” zero position after the run and before it posts a return to user defined position.
When the “Z” command is cut then moved to “return to user-defined finish pos” the machine does what is needed.
Software version is LightBurn 0.9.24
Is there an updated version the corrects this bug ?
Otherwise I’ll have to remember to edit the code when doing thick material.

Thanks so much for your guidance.

G1X73.82Y42.58
G1X73.28Y42.97
G0Z0
M107
G1S0
M5
G90
; return to user-defined finish pos
G0 X500 Y300
M2

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9

OZ in the LightBurn forum offered this :

You must be using absolute Z moves - It would likely make more sense to use relative Z moves, and just move the Z bed lower yourself before running thick material, otherwise the software will return everything to zero at the end.

You can set this in Edit > Device Settings in the top right - enable ‘Relative Z moves only’ and then if you manually adjust the Z before you start (or use the Z-jog buttons in the move window) LightBurn will only make relative moves from wherever your Z is when it starts, if the layers specify them, otherwise it’ll leave the Z alone.

Problem SOLVED

Thanks much to these forums and all the talent in them !

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