Question on K40 power supply

[Brandon K.]

Following along with http://4.bp.blogspot.com/-84-8KpcR0vY/U-UAoggAaII/AAAAAAAAEp4/aYj0-6NZ8HY/s1600/CO2LaserRampsHookup.jpg I'm wiring up a RAMPS 1.4 and Full Graphic Smart LCD setup to power my K40. What does the connection labeled "L" do?  My power supply looks identical to Dans, but there are some differences between his graphic and the power supply hes used. I was thinking that may be the laser power return path, but that is actually the first pin at the very far left on the PSU, followed by a ground and Hot/Neutral. Looking through some more pictures I don't see where he has connected the "L" terminal to anything.

[ajf]

"L" is laser fire active low on my PSU and it's probably the same for yours. I think the pin labeled "laser fire" on Dan's PSU is active high.  You only use one fire pin, so there is no need to hook up "L."

regards,

aj

[John Dickinson]

It is enable low and you can set Marlin up in mode 2 to use it.

[Brandon K.]

Thanks to both of you. I'm still waiting on a replacement tube since the original froze during shipping. Machine is coming along nicely though. RAMPS is up and controlling the gantry fine through pronterface. Tonight I'll be working on the endstops and maybe push some gcode to it. In the meantime I'm leaving the interlocks open so I dont get a 24kv surprise. I've been taking a lot of pictures of the process, just waiting on a good day to get my buildlog on hackaday.io going.

[ajf]

Look forward to seeing your buildlog!  While you're waiting for your replacement tube, you might want to double check wiring in the K40.  As noted in my buildlog, there can be some nasty surprises in these things...

[Brandon K.]

Well aware of that one.:) I've taken the machine down to every screw and bolt just to make sure of everything. I've actually upgraded all of the wiring inside the machine, and tossed that silly ribbon cable out.I broke out the stepper and endstop wiring to a drag chain. Just gotta figure out some way of attaching it to the gantry. The VHB tape I used to affix it to the stepper didn't hold nearly as well as I had hoped, so I may be building a bracket to screw it to. I'm hesitant to use the screws on the bottom of the X axis stepper since I think they hold the stepper together.

[Brandon K.]

http://hackaday.io/project/4498-40-watt-laser-cutterengraver

There is a decent placeholder. I've not used hackaday.io before. Not too sure how well I like it.. may just try and recover my old blogspot.

[ajf]

I used 7x7mm drag chain.  The X stepper and endstop weren't too bad for me, I just fashioned a bracket from some scrap sheet metal and attached it to one of the stepper mounting screws.  I replaced that stepper and added a damper anyway, so it wasn't much extra work.  However, getting the air assist tube and red dot laser wiring to the laser head carriage took a couple of iterations.  Found I needed to forgo the drag chain terminators and just mod regular links to get everything to move properly, not get in the line of fire, and not kink the tube.

[ajf]

Damn it, looks like everybody got a bigger window in their K40 than I did...

Please consider posting a link to the sticky topic when you get a chance.

[Brandon K.]

http://bluewraith.blogspot.com/

There's the first couple days all rolled into one. I'm about a week further along than the blog shows, so there may be another post once I get around to documenting the pictures.