Laser Cutter Crosshair

by joe.andolina

23K19414

Intro: Laser Cutter Crosshair

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

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!

13 Comments

SimonA88 6 years ago

Hi there, I am interested in seeing your Z probe design, I see that you have a shafted pin what is the set up with this do you use a momentary stop switch inside this?

ffesti 6 years ago

Instead of a z probe I used an additional point laser to gauge the focus point. It is on the 3D diagonal - 45 degrees to the line lasers and to the table. It hits the focus point. If you are out of focus the point moves on the diagonal of the targeting cross on the material.

The third laser does not only make selecting the right hight easier but allows watching the focus during cuts. If necessary you can pause the cut and adjust the table height.

joe.andolina 6 years ago

Do you have more info on this? It sounds like a great idea!

tim23x 7 years ago

I'm just building a laser cutter, the crosshair looks like a great addition - thanks for sharing! I've ordered the same optics as you are using but can't find CAD models for the components, did you manage to find any?

joe.andolina 7 years ago

tim23x,

I am stoked to hear you are making laser crosshairs. You can see my cad files by following the links to the Fusion360 stuff. Check out step #2.

Happy cutting

tim23x 7 years ago

Hello Joe! Cheers for getting back to me - I've got the CAD files for the laser mounts, I'm going to 3D print them, hope the quality is good enough to form an accurate spot. I'll put a link to my Openbuild project when I've made some progress. What I was wondering was if you had CAD models of the Chinese laser head and mirror mounts - I've looked everywhere but can't find any.

mohissa 7 years ago

I'd love to make this for my Shenhui laser cutter. Do you think it would work?

I've got one laser line, but going to get another one. And I have 3D printers that I can use to print the mount, but wondering how accurate this is going to be.

joe.andolina 7 years ago

It is great to hear you are going to make a crosshair. When all is setup and aligned, I get within a 1/32" for setups. Good luck with the 3D printing.

joe.andolina 7 years ago

It looks like I am a little late to this comment. The crosshair holder in my design just clamps on the laser head. For that, you don't need any cad files because that portion is a cylinder. Your models above look great.