Laser Cutter Resources

=Introduction=

Physical Setup

 * Look notyet for the dimensions of our laser bed.
 * Cooling: We need hose and water for cooling.
 * Venting: to be done better.

Class Notes

 * class notes from June 13,2015

Hints and Tips

 * In the CorelLaser CorelDraw laser driver, a LOWER speed (mm/s) actually makes the machine work FASTER.
 * Right now, under 12 or even 15, it will lose track of its position, so try to be higher than that until we figure a solution
 * Power is manually set. 3 is actually pretty powerful already. Try at this power first if unsure before going up.
 * There are three switches. The left one is not connected to anything, the middle one is the light, the right one is power.
 * There is a laser pointer to use for aim, but it is battery powered, you need to manually turn it on or off.
 * The yellow button puts a small burst of laser. It is used for calibration
 * There is a knob to calibrate the height of the table. The optimal height is when the burst you get when pushing the yellow button matches the aiming target position.

If you don't want to use CorelDraw
There are two free software given with the cutter if you don't want to use CorelDraw. I use LaserDRW. It is on the CD below the laser cutter. It is a bit clumsy but does the job. If you want to import vector graphics, you will have to go through the venerable WMF format. Inkscape can export those.

- Open your file with LaserDRW - Check the dimensions - Open the "engrave" dialog - Choose the "cutting" strategy instead of the default "engrave" if you want to cut - Selecting "nearest" will make the laser follow a path that is not utterly insane - I suggest to use a non null "fill the gaps" (I use 0.1 mm) to minimize unecessary movements - Once ready, check you have put your material to cut and click "starting". - Check the tray icon notifications, it can take long to export your paths if you have a lot of curves. Up to a few minutes. It will start eventually. - Enjoy the smell.

Problem: Using a line width of < 0.13 mm in your designes will result in some of your cutting lines dashed. Using a line width > 0.13 will make the cutter cut all your lines twice. Pick your poison. And if you find a way around that, please PLEASE write it down here!

=Materials= You can buy acrylic of all types and have it delivered from this company: http://www.hazaiya.co.jp/

We might also be able to get scrap acryl for free from Happy Printers in Harajuku. http://happyprinters.jp

=Possible Hacks= http://www.cnczone.com/forums/general-laser-engraving-cutting-machine-discussion/138554-cheap-laser-cutter-modifications.html

One hack we desperately need to do is to either remove the original bed, or move the bed height knob to somewhere else. It effectively cuts off 4CM of cutting space on the bed. Also, the screw in the knob must be a factory hack, as it is OBVIOUSLY the wrong screw. With the honeycomb in, you cant even turn the knob a full turn! WTF?!

So, short term hack: Fix the botch screw job Long term hack: MOVE the knob physically, or rip the bed out entirely.

Full open source stack
Some of us don't like the fact that you can't run it out of a totally open stack of software. The closest I got to is to run a Win7 image in a VM to run the proprietary software/plugins that it requires. I tried to see how much work would be required to make it possible to use linux and only OSS to drive it. Here are a few remarks for the brave souls who may want to walk down that path.


 * The cutter shows in lusub as Vid = 0x1a68 (Qin Heng Electronics) Pid = 0x5512 (CH341 in EPP/MEM/I2C mode, EPP/I2C adapter). This means that we are interfacing with a CH341 chip, a USB to parallel converter (or to I2C but I doubt it) which seems typical for cheap CNC cutters: their control logic is inspired by plotter printers which used to use parallel ports and even the drivers are often similar.


 * There is a driver for the CH341 in linux, but it seems to have some bugs at the time of writing (there is a patch for kernel 3.14, something more recent than that should be better). I managed to display it as a ttyUSB0 device by manually charging the usbserial module with the Vid and Pid as parameters, then creating the dev nodes. Unfortunately I did not manage to get the printer to initialize.


 * At this point, the real question is whether the USB dongle (which is not a key, but really an authentication dongle, hard to duplicate) is necessary for the cutter initialization or just for the proprietary windows software.

Replacing the board with a GRBL shield (gShield)
A gShield (formerly known has GRBL shield) has been bought in the hope that it can replace the current board. I (Yves) made some promising tests: it has no problem driving the steppers. The laser control is accessible through the power connector. I tagged "LD", for Laser Drive, on the wire that fires up the laser. It seems to be pushed up to 5V so this means that the laser fires when you force the signal to 0V. The only missing thing I got stuck on was that the Y axis has an optical sensor to detect when it reaches zero. In order to use it, we have to connect to the flat ribbon cable and I could not find a connector for that. I an pretty condfident that the gShield will be able to handle this signal.

On the software side, I did my tests using the universal g-code sender, recommended by ShapeOko (https://github.com/winder/Universal-G-Code-Sender/downloads). You will have to change the serial port speed to 115200 bauds in its settings. It then works like a charm.

= Hardware Documentation = Started documenting and reverse engineering the current board. Datasheet can be found here: http://www.3wcad.com/ Our board is the one at the very top (6C6879-LASER-M2) and datasheet is here: http://www.3wcad.com/download/M2%E4%B8%BB%E6%9D%BF%E7%A1%AC%E4%BB%B6%E6%89%8B%E5%86%8C.rar (In Chinese)

Things done: Although pinouts for most connectors are there at page 2, pinout for the flat ribbon cable is nowhere to be found. It basically combines X stepper and XY limit switch headers into one. 5V pin was tricky as it has a diode in between the 5V rail and the pin. Found the pinout and documented it. Now trying to find the cable type (Probably an FFC cable with 12 pins and 1.5 mm pitch, cable marking "awm 80c 60v 20624 vw-1", only 9 pins are used).

Here are the connector pinouts:

X-Motor-A
Pin 1 is the leftmost pin.
 * NC
 * 1) NC
 * 2) 5V (through diode M7)
 * 3) Y-L (active low)
 * 4) X-L (active low)
 * 5) GND
 * 6) GND
 * NC
 * 1) X-B2
 * 2) X-B1
 * 3) X-A2
 * 4) X-A1

X-Motor-B
Pin 1 is the rightmost pin.
 * 1) X-B2
 * 2) X-B1
 * 3) X-A2
 * 4) X-A1

Y-Motor
Pin 1 is the rightmost pin.
 * 1) Y-B2
 * 2) Y-B1
 * 3) Y-A2
 * 4) Y-A1

XY-Limit
Pin 1 is the top pin.
 * 5V
 * 1) GND
 * 2) X-L (active low)
 * 3) Y-L (active low)
 * 4) GND

Power
Pin 1 is the leftmost pin.
 * 1) GND
 * 2) LO (laser output, active low)
 * 5V
 * 5V
 * 1) 24V-30V
 * 2) GND