Being new to laser cutters, anything to make setup easier is a blessing. My machine came with a red dot to show where the cutter head is. Thats great but you have no context of where the laser is going. By adding a crosshair to your laser you will know in two directions where the head is. You can align your machine to printed graphics and materials way faster than with a dot.

A cool side effect of this project, is that the crosshair marks the same place regardless of the z-height. When I was using the laser dot, it would move every time I moved the table.

Step 1: Tools and Materials

For my build I only needed to buy the visible laser modules and used scraps from around the shop.

Materials

2x - Laser "Line" Module http://www.amazon.com/gp/product/B012V3U3KK
1x Billet of aluminum 9mm thick
1x Billet of hard plastic 9 mm thick
6x Set screws
1' Shrink tubing
2x Sockets (optional)

Tools

Milling machine
Voltmeter
Solder iron
Drill
Tapping set

Step 2: Design

Your design may vary from mine depending on your laser head and if you have a z-probe. Basically you are building a jig that clamps to the cutter head, it holds two smaller plastic sliding jigs and a z-probe. There are two set screws to hold the jig on the cutter head. There is a set screw in each plastic visible laser holder which keeps the rotation. There is another set screw in each of the grooves which keeps the visible lasers X or Y position.

I made a Fusion360 model available for you to base your designs on: http://a360.co/1I1ES5E

The slider groves and the visible laser holders have a tolerance of .05mm. If you find yourself changing the model, make sure to add or subtract and extra .05mm to/from your measurements.

Step 3: Cutting the Jig

Once you are happy with your design its time to mill it. Originally my design was all aluminum. After I assembled and powered up, I found that the laser module casings were grounded. That's no good. In the images above, the visible laser holders are metal, yours should be made from hard plastic.

Step 4: Accuracy Is Sexy

This project was my first multi part milling, I was amazed that everything fit.

After you have your parts its time to drill and tap all the set screw holes. Be careful with your drilling and tapping to make sure all the holes are perpendicular to the edges of the jig. All the holes that need tapping are in the Fusion360 model.

I added two additional non threaded holes to the ends of each slider groove. These extra holes allow access to the set screw that controls the visible laser rotation.

Step 5: The Z-probe

If your machine has a z-probe, you will need to thread the z-probe holder hole. My machine had a crazy thread on the z probe that I couldn't match. My friend has a lathe so he made me a new probe with a standard thread. The new probe uses the rear end of a drill bit as the touch point.

Step 6: Installation

You will need to cut all the connections to your old alignment laser and z-probe. I was sad to see my machine with all the wires hanging out. You should use your voltmeter to double check the voltage going to the laser is between 3-5v.

Start by soldering the visible lasers in parallel and then to the machine. If you chose to use plugs, add those in the mix too. If you have a z-probe solder it back in as well.

Step 7: Done

Now its time to use to the set screws to properly align the visible lasers with the cutter head path. I etched a square in paper and matched the red lines to the etched path. You will find the visible lasers move a bit when you tighten them, so be sure you fudge a little before adjusting the set screws.

Have fun!