Some months ago I had the opportunity to know I quadriplegic girl with difficulty in speech articulation. In order to communicate, her dad hacked a laser keychain pointer and stuck it on a pair of glasses; in this way the girl, moving the head, could direct the beam to a panel with the letters of the alphabet and highlight the right letters to create the desired phrase.
I decided to realize a 3D printed version of this useful low tech device with the following improvements:
- control the power of the laser beam (even relatively small amounts of laser light can lead to permanent eye injuries and it is hard to know the real laser class of a keychain pointer)
- ensure a good portability
- assure easy battery replacement
- make it compact and as good looking as possible :)
That is the reason why I realized the project but If you want, you can use it during your next presentation to your boss!
Step 1: Materials
- Class 2 red dot laser diode (power < 1mW, diameter 9mm, length 20mm)
A class 2 laser would not harm an eye unless a person deliberately stared into the beam. In any case, the closer you are to the laser and the longer the beam is in the eye, the greater the chance of injury.
- Small Binder clip (height 10mm)
- M3 bolt (length 10mm), washer and nut
- SPDT Slide switch (base width 10mm)
- Heat shrink for wires
- 2 parts 3D printed enclosures
- 2x LR44 batteries
Step 2: Tools
- Soldering iron
- Wire cutter/stripper
- Helping hands
Step 3: Assembly - Red Wire
- First of all print the two parts of the enclosure
I know that my home made 3D-printer is not the best but it is enough form my needs. I usually clean the plastic parts with sandpapers
- Slot in the diode between the fins
- The red wire is 100mm long; strip it 30mm from the end
- Bend the tip of the wire of 90 degrees
- Push the wire through the left hole at the base of the enclosure (that’s the trickiest part of the project)
- Pull the wire using a pair of tweezers
- Wrap the wire around the box (this is the battery holder) and press it in the space between the outer and the inner wall
Step 4: Assembly - Black Wire
- The black wire is 100mm long; cut 50mm of wire
- Strip it 30 mm from the end
- Push the wire through the right hole at the base of the enclosure
- Twist the wire and wrap it around the box.
Step 5: Soldering
Remember to add 2 small pieces of heat shrink before soldering, afterwards would be too late!
- Solder the wire from the box to the central pin and the one from the diode to the lateral pin
- Move the heat shrink close to the switch and provide heat
In case of pour contact between switch and case, add some drops of glue and hold in place the components with two clamps
Step 6: Last But Not Least
Attach the binder clip to the case with M3 bolt, washer and nut
Close the case with the cover and you are ready to point!
If you want to remove the batteries, put a screwdriver in the slot and use it as a lever to extract them... enjoy!