Hi. I finally built my CNC router last year after collecting parts and information over several years. Thanks to all who post on this forum and put their videos on You Tube.
As with us all once it was built the question was what could I add next? I've added a rotary axis and am now looking at including a laser diode. The rotary spindle is controlled through a Huanyang VFD which I have had no issues with; having wired this up I foolishly thought I had the knowledge to wire the laser but after many attempts I am stuck. The better half is constantly asking what I'm "messing about with now" and "what is that burning smell?" so it's time to ask for help.
I've read many articles on using the Z axis stepper but I would prefer to add the diode as a spindle with PWM Mach control.
The BOB is a ST-V2 and the laser control board is a SW-LD73 shown below.
Can anyone advise?
Thanks

Assuming you are using Mach3 – are you using the PC’s Parallel Port or are you using an external motion controller ?

Hi Tweakie, yes Mach3, parallel port, Windows XP.

This article gives some insight into laser switching;
http://hobbycncart.com/publ/cikkek/mach3_temaju_cikkek/switching_a_laser_under_mach_control/8-1-0-29

To obtain laser output power control the easiest method I have found is to gate the PWM signal with the Output# used with the M11/M10 (M62/M63) command set and I have described that here;
https://www.machsupport.com/forum/index.php?topic=12444.msg265104#msg265104

I await your questions 

Thanks Tweakie. I'll work my way through those articles and give it another try. I've read in the last two days all 110 pages of your laser project post, some great information in it. Thought I was catching up till I saw that the post was started in 2009 . Dilemma today is that me and the wife are going away for a couple of days to celebrate our wedding anniversary; I wonder about her response if I cancel and head back to the shed

My advice is forget the shed and enjoy a break.