Introduction: Laser Cut Spartan Laser
My six year old son came across a Halo outfit at the Halloween costume store and decided he must have it. Having devoted nearly half my waking hours to that game about 10 years ago I was plenty excited that there would be a Mater Chief walking around my house. Problem was, he came with no weapons and that is unacceptable.
This Instructable covers the creation of a very simple laser cut Spartan Laser (or more specifically a Model 6 Grindell Galilean Nonlinear Rifle". It is a simple mechanism complete with a high intensity LED on the front to mimic a laser, and make for a sweet flashlight come Halloween. I'm not artistic so I cut the build short of painting it, just wood tone here.
Everyone knows Master Chief can carry two weapons, so I also made an Energy Sword, check it out at: https://www.instructables.com/id/Laser-Cut-Energy-Sword/
Step 1: Gather Materials
This build requires the following.
- Limit switch with Normally Open contacts
- Scrap Wire
- 7 to 10 ohm, 1/4 Watt Resistor
- High intensity LED http://amzn.com/B00JR5CV4C
- Two sheets 12" x 24" x 0.25" plywood.
- LiPo battery https://www.adafruit.com/products/328
- #6 x 1.25" machine screw and nut
- #2 x 0.5" machine crew and nut (two of these)
- Spare small screws
- Laser cutter: I used an Epilog Mini at my local FabLab
- Drill with assorted drill bits
- Soldering Iron and solder
- Wood glue
Step 2: Cut Things With a Laser
Use the attached files to cut out the various pieces. Consists of two main outer plates, spacers cut up into smaller shapes to make efficient use of the wood and a trigger. I created this in Inkscape using a silhouette image off of a quick google images search. Thanks to whoever did all the hard work for me!
They are attached as PDFs, ready to send to the laser cutter. I tried uploading the .svg files but Instructables didn't like it.
Step 3: Glue the Spacers to One Side
Take one side of the Spartan Laser that you cut out and glue the spacers to it using wood glue. Get everything lined up perfect and then either clamp or stack some books on top overnight for the glue to set up. Be sure to wipe off any glue with a moist towel so you don't have to sand it off later.
Step 4: Add the Electronics
This is a simple circuit just consisting of a battery, LED, resistor and switch.
Switch: I chose a spring loaded limit with with lever arm that I had already in my parts bin. This is great because it kicks the trigger back when released without the need for extra springs/components.
Resistor: The resistor is there to limit the current passing through the LED. I bought the LEDs on Amazon so I didn't have a data sheet. I went off of customer reviews for how much amperage I could pass without requiring a heat sink. I then hooked it up to a bench top power supply and tests different voltage/current combinations and found that 2.88 volts passed approximately 140 mA through this LED. A quick calculation later and I determined that a 7 ohm resistor would cover my bases when the LiPo was fully charged 4.2v and when nearly fully discharged 3.7v. A 1/4W resistor was sufficient. I had a bag of 8.2 ohm laying around and the increased resistance did not result in a meaningful drop in light output.
Battery: I previously purchased this 2500 mAh battery from Adafruit for another project and didn't end up using it. This is a big battery for this simple project and will ensure my son can use this thing non-stop on Halloween without any worry of running out of juice when trying to kill that evil Covenant race.
LED: As I mentioned above, I purchased these from Amazon for about 20 cents each. They do not disappoint given their small package and minimal current draw.
Wire everything up as shown in the pictures. Positive of the battery to the NO terminal on the switch, Resistor to the COM terminal, through a wire to the positive side of the LED. Negative of the LED connected via wire to the negative of the battery. First grade circuitry.
Click the switch, does it light? Good job.
Step 5: Secure Switch and Add the Trigger
Now take a look at your layout and determine the best position and angle to mount your switch and trigger. Depending on your limit switch the trigger may have to have more travel, or be pressed harder. Figure out what works best for you.
Tip when drilling thin plywood: Place the board down on a piece of scrap wood with the pretty side face down. Drill through the plywood and into the board while pressing down firmly. This keeps the plywood from splintering as the drill bit exits.
Drill the holes for the limit switch: Once you know your position, mark and then drill holes. I used #2 machine screws and nuts to secure mine.
Drill the holes for the trigger: Same as above. I used a #6 machine screw for this. I added a small piece of scrap wood behind the trigger level to minimize its travel and make it move more realistic.
Once everything is in place secure the battery with a bit of tape. Nothing too strong, you are going to need to remove it for charging at some point.
Step 6: Install the Other Side. Finished!
Install the other side, line up carefully and clamp in place. I found some small screws in a scrap drawer and installed them in 5 spots around the perimeter to hold the side on. Do yours as you please, but don't glue this side on unless you include some access to be able to charge the battery.
This thing will light up the street, an entire room or let approaching cars see your kid walking down the street.
The best part of all is seeing the smile on your kids face when it is all finished. This is an easy project to build with your little one. Mine loves going to the FabLab with me and running the laser cutter.
Be sure to check out the Energy Sword at: https://www.instructables.com/id/Laser-Cut-Energy-Sword/
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