How to connect laser fire pin of K40 CO2 laser to Duet board.

jay_s_uk

any chance you could post your config?

j.dewit

@jay_s_uk Sorry for the late reply, my notifications were turned off.

I will try to post the config tonight.

Some update on the project, I now have added an controllable Air assist using a Relay. That is controlled via gcode commands. And I have added a motorized Z-table.

Both were easy to configure in the Duet, and work great.

I do have a fully working k40 now, with the option to control the laser intensity from software. Gcode generated from LaserWeb is working perfect. I then upload these to the Duet, and that seems the way to go.

I haven't had any luck on getting the gcode from the Lightburn software to work to an acceptable level. The generated gcode does work, but whenever I use a fill, the results are bad. Jagged edges and wobbly lines.

I will need to find some time, to post some example pictures and the used gcode. Since I haven't found out what exactly is going wrong with the gcode from LightBurn.

j.dewit

I have added my config file: (Comments may be a mess....)

; General preferences
G90 						; send absolute coordinates…
M83 						; …but relative extruder moves
M550 P"MPCNC" 					; Machine name and Netbios name (can be anything you like)
G21						; Work in millimetres
M555 P2						; Set output to look like Marlin

; Communication and general
M111 S0                            		; Debug off
M551 Preprap                   			; Machine password (used for FTP)

;*** Networking
M540 P0xBE:0xEF:0xDE:0xAD:0xFE:0xED		; MAC Address
M552 P192.168.0.50				; IP address
M554 P192.168.0.255				; Gateway
M553 P255.255.255.0				; Netmask
M552 S1						; Turn network on

; Pin for air assist via relay
M950 P0 C"fan0"

; Drives
M569 P0 S0					; Drive 0 goes backwards
M569 P1 S1					; Drive 1 goes forwards
M569 P2 S1					; Drive 2 goes forwards
M569 P3 S1					; Drive 3 goes forwards
M569 P4 S1					; Drive 4 goes backwards

; Drive mapping
M584 X0 Y1 Z2 E P3			        ; Drive mapping

; Drive settings
M350 X16 Y16 Z16 E16 I1	         		; Configure microstepping with interpolation
M92 X157.575 Y157.575 Z3232.57		        ; Set steps per mm
;M350 X32 Y502 E128 I1				; Set steps per mm for the extruder to x128 (776 steps per mm) and X and Y to x32 (160 steps per mm)
M566 X800 Y800 Z60 E3000 P1		        ; Set maximum instantaneous speed changes (mm/min)
M203 X16000 Y16000 Z40		                ; Set maximum speeds (mm/min)
M201 X2500 Y2500 Z80		                ; Set accelerations (mm/s^2)
M204 P600 T2000					; Set accelerations (mm/s^2) for print and travel moves
M906 X400 Y600 Z600 I30		                ; Set motor currents (mA) and motor idle factor in per cent
M84 S0						; Set idle timeout

; Axis Limits
M208 X0 Y-30 Z-13.6 U0 V0 S1	                ; Set axis minima
M208 X300 Y200 Z70 S0		        	; Set axis maxima

; Endstops
M574 X1 S1 P"xstop"  ; X min active high endstop switch
M574 Y2 S1 P"ystop"   ; Y max active high endstop switch
M574 Z1 S1 P"!zstop"  ; Z min active high endstop switch

; Allow movement before homing
;M564 S0 H0

; Laser Mode
M452 C"e0heat" R1.0 S1 Q200                          ; laser uses !e0heat pin,  PWM frequency 100Hz

jay_s_uk

thanks @j-dewit

I ran my K40 with a duet for about 2 hours and gave up as I couldn't get any good engraving out of it.
The firing of the laser didn't want to keep up with the movement of the machine so just looked awful.
I might revisit it at some point, but getting even something remotely useful out of lightburn was difficult

j.dewit

@jay_s_uk Seem to be having the same results here, but the gcode from laserweb is working absolutely perfect.

I have done some g-code comparisation:

LaserWeb:

; Pass 0 Path 1
G0 X40.18 Y4.49
G1 X39.07 Y4.49 S0.40 F10000

; Pass 0 Path 2
G0 X39.07 Y4.59
G1 X40.18 Y4.59 S0.40 F10000

LightBurn:

G1X13.92F10000S0.4
G1Y0.1S0
G1X-13.92S0.4
G1Y0.1S0

So far the only difference I see is the G0 moves in laserweb, when the laser is off by default. And in lightburn it is using a G1 with laser power to 0.
And the difference in absolute and relative movements. But why the duet is having problems with the lightburn gcode is a mystery to me.

jay_s_uk

I'll look at using laserweb as an option then.
I used to use it before I got lightburn and changed as I just never got on with it.
I'll add this bad on my jobs list to look at.

is the engraving working well using laserweb then?

j.dewit

@jay_s_uk I have not tried images etc.

But filling vectors works well.

LaserWeb is a good piece of software, but it being totally free. It just can't be compared to lightburn as this is a far superior piece of software.

jay_s_uk

@j-dewit

ok, thanks.
Its more vector engraving I do so I'll look into it.

j.dewit

@jay_s_uk And I am planning to spend some more time testing why the g-code from Lightburn is a mess, I have ordered a cheap MKS S-base board since it should be compatible with lightburn, but I would rather keep using the Duet, since everything on the s-base is a big downgrade compared to the duet.

jay_s_uk

@j-dewit

I currently run mine with the SBase (running grbl-lpc https://github.com/cprezzi/grbl-LPC) and the performance is spot on.
It may be down to grbl having next to no features compared to RRF.
I'd just prefer to have wireless support so I can run my machine without being tethered to USB. And I'm a fan of the duet ecosystem.

The lightburn gcode could also do with way better structure. I think the outputted file is quite messy