Adding a 3.5watts Laser to my Shopbot Desktop

[Marc F. Lupien]

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/aow9m5t0c2cpk7q/Shopbot%20Desktop_my%20laser%20installation%20note s.pdf?dl=0

[steve_g]

Marc…

Thanks for taking the time to document this!

SG

[Marc F. Lupien]

You are very welcome.

[barrowj]

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

[zeykr]

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

[Marc F. Lupien]

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.

[Marc F. Lupien]

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.

[barrowj]

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

[Marc F. Lupien]

Here are some tests I did with it.

33109 33110 33111 3311233113

[jTr]

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

[coryatjohn]

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

[Marc F. Lupien]

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.