Beam Dynamics Laser Cutter Tutorial

The CBA shop has a 4' x 4' Beam Dynamics laser cutter. This is a work-in-progress tutorial for their machine.
Wondering if your material is safe to laser cut? Check out Pololu's list of laser-cuttable materials

Creating a Drawing

1. Create the pattern you are going to cut using a drawing program like CorelDraw

2. Export your drawing in HPGL (.plt) format

The Beam's LaserLink software can import HPGL files (.plt), and Drawing Exchange Format files (.dxf). I have had (by far) the most success with HPGL files. CorelDraw11 lets you export drawings as .plt files. An HPGL file is also easy to generate programmatically--it's a list of x,y coordinates that are preceded by either Pen Up (PU) or Pen Down (PD) commands. A PU command moves the plotter to the specified point without cutting/drawing and a PD command moves the head while cutting or drawing. Download a sample HPGL file

If you must use another format, you can generate .dxf files that will open in LaserLink by importing a vector file into Rhino and then exporting it as a .dxf. Make sure all of the lines in your drawing are on the same layer and that your drawing contains no groups. Nested groups especially cause all sorts of problems in the LaserLink software. I cannot recommend using HPGL files strongly enough. I have had consistent inexplicable and frustrating software/firmware problems when using .dxf files.

Laser Link Software

LaserLink software manual

3. Open the LaserLink software

Here's what the software looks like with a 4 layer drawing. (Each layer was imported as a separate HPGL file.)



4. Import your drawing

Go to File/Import and select the appropriate file format

5. Editing your drawing

The LaserLink software is not terribly user friendly. To accomplish any action:
a) left mouse click
b) select the area of the drawing you want to modify
c) left mouse click again
d) right mouse click
e) left mouse click to begin your action (moving, copying, etc.)

6. Save your drawing.

If you don't save your drawing, edits that you made may not be reflected in the toolpaths.

7. Create the toolpaths for your drawing

a) Create a new material entry in the "database table" with the speed and power settings appropriate for your material. Click on the "database table" icon and fill in the entries for your material.





b) Define the "process table", the laser cutter toolpath, for your drawing. Click on the "process table" icon. For each layer in your drawing, select the appropriate material. Here's the icon you click:



And here are the two windows you'll navigate through. In the first one, you select the layer you'd like to process and in the second one you select the cut settings for that layer:



c) Create the "process" by clicking the "process" icon or by clicking "process" after you've created the process table. Save the process file to: C:/BeamDynamics/JOBS.


BeamHMI Software

8. Open the BeamHMI software

This is the control interface to the machine. This is what the main window looks like when you first open it. Notice that the Status indicator in the upper right hand corner of the window is telling you to home the machine.



9. Home the machine

If you get a motor fault message (which I sometimes get the first time I try to home the machine), turn the machine off with the key and with your hand move the head around a bit in the x and y directions. Turn the machine back on & rehome.

10. Load your job

Click on the Load button and browse to your file. This is what the main window looks like once you've loaded a job. Notice that you can see the cut settings up at the top and the Status message now says "Ready to machine".



11. Do a dry test run

Turn the laser cooler off. Hit start on the BeamHMI software. This will move the laser head along the paths of your drawing without cutting.

12. Cut your job.

Home the machine. Turn the laser cooler on and hit start on the BeamHMI software to begin cutting.

Troubleshooting

Note: the machine and software are pretty buggy, frequently exhibiting inexplicable behavior and errors. I've listed a few of the problems (& solutions) I've encountered below, but the list is by no means exhaustive. When in doubt, home the machine. If that doesn't work, cycle power. If that doesn't work, restart the software.

Problem: I press Start in the BeamHMI software, but nothing happens.
Solution: Home the machine and try again.

Problem: I press Start, and the head moves, but it doesn't cut.
Solution: Make sure the laser cooler is turned on and try again. If that doesn't work...
Home the machine and try again.

Problem: Motor head fault.
Solution: Turn off the machine, manually move the head around with your hands. Turn the machine back on. Home.

Problem: Focusing error/fault.
Solution: Home the machine and try again. If that doesn't work...
Move the Z axis up or down a bit using the controls in BeamHMI (Be careful not to crash the table into the head of the laser!). Home the machine & try again.

Problem: 1062 X Y Encoder Failure.
Solution: Power cycle the machine (turn the key to the off position, wait fifteen seconds, then turn it back to the one position). If that doesn't work...
If the failure always occurs when one axis of the machine reaches the same position (for example, whenever the X position is at 8.671 inches, when manually jogging around, regardless of the Y position), then there may be schmutz buildup on one of the optical position encoders. Cleaning of these encoders requires some disassembly of the machine, which the shop managers would be happy to help with. There are special tools required to do this properly, so please do not attempt this outside of normal shop hours.

Problem: Not cutting consistently (all the way through or same kerf width) across a large piece of stock.
Solution: Try grouping your toolpaths as individual processes for smaller areas, and set each of these processes to refocus. It will focus inside the bounds of the vectors for each process, which can correct for low frequency warpage of your stock material (and the honeycomb bed). If that doesn't work...
If the stock is warping because of the heat during cutting, you may have to strategize your cutting sequence in a more complex way, in order to allow the material to expand without popping out of the x-y plane. This will depend greatly on the geometry of the part. \\\