Adding a 3.5watts Laser to my Shopbot Desktop

Hi everyone,

I recently installed a small laser on my Desktop 2418.

I asked for help from the Shopbot technical staff but it turned out they did not point me in the right direction and I ended up spending many $ on a new control-card for nothing. That’s why I’m posting this. I want to share some info with others who would be interested in doing something similar with their CNCs.

Here is a very brief overview:

1- Bought a 3.5w laser from china (laser, power supply, goggles …).
2- Found an existing signal on the Shopbot Desktop control-card to control the laser with variable intensity (as opposed to full power/no power).
3- Used a couple of electronic devices to interface the laser control with the Desktop so that they don’t share common ground (completely isolated electrically).
4- Created a new post-processor for VCarve to create cut-files.

For a detail explanation, you can check this pdf document :
https://www.dropbox.com/s/aow9m5t0c2...notes.pdf?dl=0

Marc…

Thanks for taking the time to document this!

SG

You are very welcome.

Marc - Wow, that is awesome. You really did good on this and we all appreciate the quality of the work so others could possibly add a laser to their machine.

Joe

Thanks for the detailed write up! This is something I've wanted to try.
Can you show us some projects done with the laser?

Thanks for the positive response. I hope my writing is «readable»... (I'm french Canadian eh! :))

Unfortunately it's been only a week so far and I gave my first protypes to a friend :(

I'll make new ones shortly and post the results.

News update...

I have been in touch with the Shopbot tech support today regarding the fact that the laser won't turn off when the cut-file is interrupted...

They tell me their design intended to turn off the PWM signal when the user hits a «stop», just like with other outputs like a router. It's a bug that got through with their development and they are currently looking into it. They will try to get a fix for it in the software and push an update to the website and issue a new version of SB3.

In the meantime, they suggested pairing the PWM signal with another output (like output2 from the control-board) so that the PWM is turned off when output 2 turns off...

Personnaly, I think I'll wait and see if Shopbot can fix it, if not, I'll add a few components around the optoisolator in the control box to shutdown the PWM signal if output #2 is off. A small transistor and a few resistors would do the trick.

Sounds like a good workaround while waiting for a fix from ShopBot. Please keep us informed...

Here are some tests I did with it.

Attachment 33109 Attachment 33110 Attachment 33111 Attachment 33112Attachment 33113

Looks like that's working swimmingly well. The foam cutting is something you don't immediately think of for a laser use.
Well done!
jeff

Jeff - What kind of smoke, gas, etc. is released when cutting foam?

coryatjohn - I think styrofoam melts more than it burns. I did not see smoke comming out, I would not worry much about it. Wood, on the other hand, burns somewhat and the laser has to move rather slow to make a consistent mark so it will generate some fume in the shop.