A week ago one of my boys went on a field trip to CalTech to see some robots and was a bit intrigued so this past weekend I took some 1 inch PVC piping, wood and some other items and showed him how to make a mechanical hand prototype. Its butt-ugly but was a fun project to make. If you dont have PVC or wood laying around, boboa straws and cardboard can be used.
- Small block of wood
- 3 feet of 1 x 1 wood (for handle)
- 3 feet of 1 inch PVC piping
- Duct tape or painters tape
- A window blind or flexible plastic
- Small hand saw
- Spade bit (flat drill-bit)
- 3/8 drill-bit
- All purpose glue
Taking a block of wood I drilled four holes where I will glue and seat the PVC piping, two horizontal and to at an angle but not all the way through. When finished I took a small drill bit and drilled a hole through the center of each one to accommodate pieces of string.
In cutting the PVC for the fingers, I cut eight pieces at 2 1/2 inches and four at about 1 1/4 inches, although for one finger I only used two pieces. I cut the window blind width-wise for 7 pieces. Roughly they are 4 inches by 3/4 of an inch.
The fingers were assembled prior to gluing in place. I placed one of the tabs cut from the window blind on one of the 2/12 inch pieces of PVC and taped it in place and repeated for the other digits, leaving about 1 inch to a little more than that between pipe pieces. This gives the fingers room to bend.
Once the fingers were assembled I glued them in place, making sure they were pointed the right way for when they bend. What would be the pinkie digit and thumb digit of the four I glued at a bit of an angle for a bit better gripping movement.
Once the glue had dried I measured out the handle part, cut it and mounted it to the hand. Using a larger piece of PVC I cut four rings which will be tied to strings for each finger. Once finished I taped string to the top digits of each finger and fed them through the holes where I then attached the rings, adjusting for fit before deciding on tying the knots.
This was just a prototype of a mechanical hand to demonstrate a bit of the mechanics that goes into building a robot. Its not a glorious project but I think it served it learning purpose.