Laser Cats

This instructable shows you how to make your very own Laser Cat robotic pet. This robot walks and purrs. Every time the Laser Cat purrs lasers shoot from it's eyes.

WARNING: This takes a toy and adds lasers to it. This means it is no longer a toy for children and this should not be actually attempted by anyone. Misuse of lasers can cause permanent blindness or vision loss. Wear appropriate laser protection glasses.

KEEP THE FINAL TOY AWAY FROM CHILDREN!

Materials needed:

1 FurReal Lulu's Walking Kitties
2 Laser Diode assemblies. - Mine came from a double flashlight pack from Home Depot. They were on clearance for around $3.50. For this you got 2 LED flashlights, 1 with a red laser, and 6 AAA bateries. Can't beat that price. For comparison all the other flashlights with lasers were in the $+50 range.
~16 inches of multi-strand wire in 2 colors
Super glue gel
Heat Shrink Tubing
Black Acrylic Paint

Tools Needed:
Wire Strippers
Soldering Iron
Heat gun
Dremel with bits
Small files or rasps fit for plastic
Screwdrivers with various small bits
Toothpicks
Sharp scissors or craft knife
Vise – These two were needed to get the laser diodes from the flashlights
Hacksaw

Step 1: Disassemble a Kitty or One Way to Skin a Cat

Turn your walking kitty over. There is a velcro fastener holding a slit shut. Our first step will be to slightly enlarge this opening by cutting the threads that hold the butt area shut. Once cut this will allow greater access to the guts of the cat.

Look for plastic tabs that hold the fur close to the plastic body. With a small flat blade screwdriver attachment press the tabs to free them from the slots. There are two towards the front of the slit that can't really be removed yet.

Start at the back leg the most forward in walking position and slowly work the fabric off of the plastic leg. Any time a plastic tab/slot holds you back use the screwdriver to separate them. Now that the one leg is free proceed with the other back leg.

Bring the fur up over the back of the cat. Separate the tab/slots on the sides of the body. This should allow access to the screws holding the back cover on. Remove these screws. There should now be access to a screw that holds the front legs on each side. Remove this screw. Now almost the entire skin can be pulled up and over the head.

Remove the leg cams and the linkages to the back legs.

The head is the trickiest part to get off. Remove all screws from the head face and eye areas. The nose and the eyes snap into sockets. The face portion should separate from the head part. Use the heat gun to slightly soften the tabs that hold the eye balls in place. Once softened use the screwdriver to slightly bend the tabs and enlarge the holes. The eyes are keyed with different numbers of fins and the four finned eye is much harder to remove.

Step 2: Kill a Flashlight

Wear safety glasses for all these steps

Other sources exist but I got my lasers from a LED laser flashlight. They were a bit tricky to disassemble so I'm providing steps on them.

I found no way to remove the laser from the flashlight head with out destroying the flashlight.

Remove the head of the flashlight by unscrewing it. Look in the end of the threads. There is a ring of internal threads that are actually threaded into the flashlight housing. If this could be removed dis assembly would be much easier and the housing would survive. I found no way to do this with the tools I had on hand.

Mount the flashlight head assembly in the vise and hacksaw down through the aluminum housing. You have to cut all of the way through.

Take a larger flat blade screwdriver and inset in the cut. Twist and pry until the crack opens wide enough that some of the parts can come loose. Careful as the front lens is glass and can break if the wrong torque is applied. Remove the threaded ring. Now look for a spring loop holding the rest in place. Pop up one end of it and pry it loose. Once this is gone the rest will come apart easy.

Remove the black plastic section. Pull the large spring out with a pliers and cut the short lead off leaving the wires on the laser diode assembly

Several cool parts are left over including the LED ring and the aluminum body.

Step 3: Cat's Eyes

Take the removed eyes and drill a hole from the back of the eye out the front. Use the existing hole as a pilot hole. Try to keep it straight as this will help immensely later. The bigger the hole the easier to align the lasers but the more noticeable the holes will be.

Once the holes are drilled in each eye, take a toothpick and apply black paint to the inside of the hole. This helps block the laser glow through the clear piece as well as camouflage the physical hole.

Strip the ends of the laser diode lead. Strip the ends of the colored extra wires. The wire length will need to go from the eye sockets back to the speaker of the cat. Soldier the long wire leads to the short laser diode leads. Test the lasers by taping the leads to the positive / negative ends of the battery holder that came with the flashlights. If the laser doesn't light, reverse the leads. Remember this is a diode so electricity can only flow one way through the part. Heat shrink the exposed wire areas.

Now comes the tricky part. With the lasers on align the laser up with an eyeball so that the laser beam passes out correctly from the eye. If this is too difficult drill the hole larger and repaint. Apply superglue gel to just the outer rim of the diode assembly. Take care not to get any on the lens. Press and hold to the eye keeping the laser pointed correctly. Hold till set. Trust me this is the hardest step. It took me many tries before I found this procedure that works. Repeat for other eye. Remove wire leads from battery packs.

Step 4: Prepare the Head

The Laser diode assemblies will sit in the eye socket holes of the head. Using either the files or the dremel, enlarge the holes to be very slightly larger then the laser diodes. You want a loose fit for the small circuit board section which can be slightly wider then the metal part.

Remove the plastic pin that connects the head to the black neck section. The easiest way is to cut off the holding tabs. Unfortunately the neck attaches just where the new lasers will sit. Use the dremel or files to create round depressions in the black plastic over the connection hole. Remove enough to allow the lasers to fit without cutting all the way through. Reattach the neck pin. Remove any other plastic to make it sit flush in the bottom of the depression. Clip most of the protruding section. Use the soldering iron (not the tip!) to melt the other side flush with the bottom of the depression.

Step 5: Lasers Powered Up!

FROM NOW ON MAKE SURE THE BATTERIES ARE REMOVED FROM THE CAT!

Now you should have two eyeballs with lasers glued to them with long leads off the end. From the face of the cat fabric thread each eyeball's wire leads through the hole in the fabric. Thread them through the plastic face section and then through the head eye sockets. Carefully push the laser diodes through the holes. Snap the eyes back into place. This is a bit tricky but reattach the face and fur/nose back to the head plastic piece. Screw the screws back into the head assembly. Keep the fur still bunched up around the head.

Remove the speaker by flipping it over. It just rests on a few pegs.
Soldier the leads of the lasers to the two solder pads of the speaker. It is important to get the negative and positive leads correct or your lasers won't fire.

Carefully insert the batteries with the cat face away from you but where you could still see the lasers from the eyes when on. Turn on to Try Me. Press the switch on the back in front of the speaker. If soldered correctly, when the cat makes sounds the lasers will fire. Once completed route the wires over the top of the circuit board and replace the speaker.

Step 6: Reassemble

Remove the batteries again. Its easy to activate the lasers in the next few steps and you don't want to be zapped in the eyes.

Add back the leg cams and linkages, and make sure they are seated properly. Attach the front legs and screws. Make sure the cams are offset from the right leg and left leg. Make sure the peg rides in the channel
Reattach the top plastic piece and screw back together. Make sure to reattach any tab/slot areas. Work in reverse and add the fur back over the body and legs.

Add the battery pack and reseal up the velcro. I didn't find much reason to resew the small area first cut .

Enjoy your LASER CAT!