This laser module holder drops a laser pointer into the beam path of the laser cutter when the door is open. When the door is closed it swings the laser up out of the way. This is an alternative to using a beam splitter or a knife-edge mirror to join the red laser with the cutting beam.
This is intended for the http://www.buildlog.net/ 2.x Laser cutter, but could be adapted to others as well.
This is inspired by http://danielbauen.com/make/index.php/laser-cutter/laser-inline-red-laser-pointer-solution-without-using-an-extra-m/ which I have admired for some time, but the STLs provided there have some features that make them awkward to print.
Prepare the raw prints:
- Drill out the pivot hole to pass M3 (or whatever you decide to use as the hinge pin). 1/8" works well for 3mm with very little wobble.
- Use the same bit to drill one of the hinge holes (I prefer the right one because I'm right handed and there's more room on that side to slide the hinge in). Keep in mind the hinge is installed upside-down and with the bevel facing the cutting table.
- Tap the other hinge hole. This will not be used to truly "tighten" the hinge pin, it will just be used to jam a M3 nut against it to keep it from moving.
- Tap all 3 of the laser aiming holes for M3.
- Ream out the barrel for the laser for a snug slip-fit on the laser module. Mine is 12mm with the sticker removed. The barrel tapers so it's wider at the base so the adjustment screws can push the base around.
- Assemble temporarily and make sure the hinge moves freely.
- Extend the wires on your laser module to reach your electronics bay
- I got 5V from the water chiller safety loop header on the laser interface board (the 3 pin removable terminal block). The middle pin is 5V, the one closer to the parallel port (pin 3) is ground. There's also 5V at the fan terminal block on the opposite side.
- I tested with a pot to find a voltage where the laser was clear and visible but without "blooming". At 2.1V I get a clear spot with much less haloing. That requied a 220R resistor in my setup.
- Don't forget to focus the laser (if necessary) before you start! The front does not actually directly focus the laser, there's a ring just behind it you adjust and then the front ring can be screwed down to secure it.
- Slide the laser module in so it's held snugly at the front of the barrel and flush with the back.
- Thread in 3 M3 adjustment screws at the base of the barrel and adjust them to roughly center the pointer.
- Secure the laser pointer leads with the provided ziptie holes. You really don't want them falling into the beam path and you want to take all the strain off the wires at the module.
- Attach the hinge to the rail behind the lid. The bevel goes toward the cutting bed. You'll need 2x M5x10 and 2 post-install t-nuts. Try to get the hinge straight and eyeball the gap in the hinge to ensure the holder won't hit the mirror table or the big laser.
- Repeatedly: Put the holder into the hinge, slide in the pin (threading it partially into the far side) and observe the laser spot point. Think about how the pointer needs to move to get it on target (you can wiggle the arm a bit to remind yourself which adjustments will have what effect). Take the arm back out (carefully!) and makes small adjustments to the M3 screws.
- A few rounds of (5) will get you roughly on target. Now if you want more precision you can close the lid, do a quick testfire onto a piece of cardstock and see if the red spot hits the hole in the paper. Repeat the steps of 5 with much smaller adjustments each time.
- I routed the wire through the T-slot in the rail behind the lid.