I have acquired a 40 watt infrared CO2 laser engraver. Here are some pictures and notes on how it works.
It burns most organic materials (wood, leather, cloth, paper) but isn’t really strong enough for cutting metal, although it is used for anodizing lettering on metal and glass. Plastics will burn, but make some pretty nasty fumes. To handle the exhaust, I configured an inline fan with a large carbon filter made for odor control:
That’s a 6″ Vortex inline centrifugal fan on top of an 8″x24″ Phat Filter, both acquired off the shelf from The Grow Show local hydroponic supply. It pulls the smoke and fumes out of the enclosure pretty well. Here is the inside of the work area:
The laser reflects off that mirror on the end of the Y-axis gantry, and is directed downward by the second center mirror on the X-axis flying jig. Here are the electronics:
The large back PC board is the laser power supply, the 12V accessory power supply is in the center, and the stepper motor control board (second picture) is mounted to the front inside of the box. I suppose the coolest part is the laser tube itself:
The tube goes across the back of the box, and is water cooled, see the jug and small hoses going to it on the left. Here is the business end of the tube, and the first gold reflector mirror that sends the beam to the gantry mirror in the front of the box:
To drive it, I’m using a 12 volt powered VIA EPIA 1GHz Nehemiah machine that I once had in mind for use as a carputer. That didn’t work out, but it has plenty of power to drive a copy of EMC2 with the dedicated RTOS Linux kernel.
So far, initial tests have shown that the filter and fan work pretty well, but don’t completely solve the problem, as when burning a test pattern into a CD case, there’s still a bit of smoke… however the fumes (burning styrene smell) are very greatly reduced. I
may have am looking to add some kind of additional HEPA filter.
On the lowest possible power (~5mA), it will cut a business card and melts the clear plastic of a CD case. My original purpose is to be able to cut stencils for solder paste when making PC boards, and also to try ablating the paint off of copper clad PC boards for soldermasking. I know it won’t cut copper, copper absorbs the infrared and won’t burn, but I should be able to burn the paint off the top of the copper then, right? I will see.
Regarding the CD cover test: This was WAY stinky. I won’t be doing this again.
The store front for this laser is LightObject.com. It was shipped direct from China (Wo ai zhongguo ren!), and had minimal delays considering it was covered in green “EXAMINED BY U.S. CUSTOMS AND BORDER PROTECTION” tape. Somebody did actually engineer it with a 3-axis stepper motor controller, so the interface to it is a standard LPT port. Other laser engravers I’ve seen on the market don’t have this capability, or use some rather proprietary looking Windows based software and/or USB driver, so this was highly desirable and worth the extra cash.
The documentation is… completely absent. All attempts to discover any technical information about the stepper motor controller board online have been fruitless, it’s a variant of the “3 Axis CNC TB6560 Stepper Motor Driver Controller Board – Toshiba TB6560AHQ chip”, which seem to have endless Asian suppliers, but this board has surface mount components, an isolated relay for the laser enable, and a few DIP switches that I have no clue about. I did get one CD from LightObject with a Mach3 configuration file (in raw non-whitespaced XML). Studying the file and gleaning what I can, I’ve got the X and Y axis step and direction pins, and it moves pretty fast, so I think I might have them set right. I can also turn the laser on and off, so those are the absolute essentials. Now that I know a little more about what’s inside the box, a cheaper laser could have the controller guts replaced with a known and documented controller, maybe even with a digital PWM for the laser power, but EMC2 might be able to do this as well. There’s a potentiometer on the front panel for the power, it adjusts from ignition at ~4mA to full blast at ~21mA. I’m assuming that this means the power supply is around 2000 volts.
It includes outputs for the X/Y axis minimum limit switches, so it can auto-home. The stage has a spring loaded clamp for mounting flat stock about 3″ by 6″, and it looks like I may be able to replace it with a vacuum base or just a regular flat metal base if I want. The “kill” switch appears to be hooked up, but does absolutely nothing. The total area of the stage is 320mm x 235mm.
Jo-Anne Fabrics and Crafts had sheets of mylar, and I’m finding that the cad.py Python script will convert a PNG file to GCode. There’s some trouble with scaling, but I’ll figure it out.
The #EMC IRC chat channel is being helpful in solving the problem with the laser beam switching on the Z-axis. I like the idea of a laser tool “plunge rate”… at 10600 nanometer wavelength, should I set the Z-axis plunge rate to 186 thousand miles per second?
I’m taking some advice from the #emc channel on freenode.net IRC. Thank you Jymmmm, who upon viewing the pictures here was very quick to note that the Vortex fan and the Phat carbon filter aren’t capable of doing this job. The centrifugal fan is good for normal air flow, but it doesn’t have the static pressure necessary to really pull the smoke out of the laser enclosure, and the smoke would goof up the optics if I don’t get that working right. I’ve acquired a blower from Harbor Freight (also per advice… and the exact model recommended was on the shelf at a HF store 5 miles away) and I’m in the process of hooking up a 4″ duct to vent it outside. This was very good advice, and right on the money. I’ll keep the Vortex and Phat filter, but I’ll likely put a HEPA filter on top and use it in my study as a general purpose air cleaner.
I also acquired some 3-mil clear polyester (mylar) from Grainger Industrial Supply, along with assorted HVAC parts for the exhaust vent, and I’ve discovered that I love Grainger. I can order online and pick it up at the Will Call window, with all the charm and professionalism of old full-service auto parts stores.