Step 6: Building the Claw Hands
For the robot claw hands, I used a 4" diameter x 6.5" piece of galvanized ducting to house the assembly. The flaps at one end that would be used for slip fitting and hose clamping on another duct were pounded flat with a mallet. Six of the flaps were folded over completely to provide clearance for the claw mechanism.
The springs were looped through a piece of old coat hanger on one end and it was bent through the two holes on the center of the top plate. I squeezed it flat with some needle nose vice grips and the trimmed off the excess.
Then the claw pivot plates were installed with one rivet each leaving three rivet holes open to secure the plate to the ducting.
I bought #8-32 bolts, nylock nuts, and washers for the pivots but I didn't have any parts with me. I was kind of eyeballing it and they turned out to be a hare big for the holes I had drawn on the parts. I had to drill all of the claw pivot holes up to size along with the holes in the claw pivot plates.
Then I installed the claws into the pivot plates using two washers per claw to take up the extra space.
The spring ends were the perfect size to slide a rivet through so I riveted them into the holes on the ends of the claws.
I couldn't find any string so I used some thin gauge wire as the pull cables for the claws. I tied on the wires and test fitted the claw mechanism into the ducting. Pulling straight down on the wires had the undesired effect of partially actuating the claws.
The mechanism was then match drilled and riveted onto the ducting.
Next thing I tried was riveting plastic wiring guides to the inside of the ducting. I routed the wires through those so when you pulled down on the wires, they were pulling the claws towards the wall of the ducting. This worked pretty good.
I then worked on the pull mechanism. I used clamp on loop end wiring connectors on a key ring big enough for a finger to fit through. I got two of them to work but in trying to secure the third one, I cut through the wire by mistake and was unable to attach it. So two out of the three claws worked. I also looped a rubber band through the key ring. This is to be secured around the dowel rod handle to keep the keyring pulled to where you can reach it.
I cut some coat hanging closet dowel rod down to fit inside the ducting. This is for the handles. I match drilled through the ducting into the dowel rod with an 1/8" bit from both ends and then removed the dowel rod. The holes in the ducting were drilled up a couple sizes to provide clearance for #10 x 1" wood screws. The handle was then screwed into place.
Last step was to wrap the sharp edges in duct tape to protect our hands.
I was short on time and decided to forgo the claw actuating mechanism on the rest of the hands so I could finish the costumes in time for our Halloween party. All of the claws were assembled with springs but only one would open and close. Need to partially disassemble and finish build these.
The video below shows the claw hand working and I tried to show the internals after assembly.
The springs were looped through a piece of old coat hanger on one end and it was bent through the two holes on the center of the top plate. I squeezed it flat with some needle nose vice grips and the trimmed off the excess.
Then the claw pivot plates were installed with one rivet each leaving three rivet holes open to secure the plate to the ducting.
I bought #8-32 bolts, nylock nuts, and washers for the pivots but I didn't have any parts with me. I was kind of eyeballing it and they turned out to be a hare big for the holes I had drawn on the parts. I had to drill all of the claw pivot holes up to size along with the holes in the claw pivot plates.
Then I installed the claws into the pivot plates using two washers per claw to take up the extra space.
The spring ends were the perfect size to slide a rivet through so I riveted them into the holes on the ends of the claws.
I couldn't find any string so I used some thin gauge wire as the pull cables for the claws. I tied on the wires and test fitted the claw mechanism into the ducting. Pulling straight down on the wires had the undesired effect of partially actuating the claws.
The mechanism was then match drilled and riveted onto the ducting.
Next thing I tried was riveting plastic wiring guides to the inside of the ducting. I routed the wires through those so when you pulled down on the wires, they were pulling the claws towards the wall of the ducting. This worked pretty good.
I then worked on the pull mechanism. I used clamp on loop end wiring connectors on a key ring big enough for a finger to fit through. I got two of them to work but in trying to secure the third one, I cut through the wire by mistake and was unable to attach it. So two out of the three claws worked. I also looped a rubber band through the key ring. This is to be secured around the dowel rod handle to keep the keyring pulled to where you can reach it.
I cut some coat hanging closet dowel rod down to fit inside the ducting. This is for the handles. I match drilled through the ducting into the dowel rod with an 1/8" bit from both ends and then removed the dowel rod. The holes in the ducting were drilled up a couple sizes to provide clearance for #10 x 1" wood screws. The handle was then screwed into place.
Last step was to wrap the sharp edges in duct tape to protect our hands.
I was short on time and decided to forgo the claw actuating mechanism on the rest of the hands so I could finish the costumes in time for our Halloween party. All of the claws were assembled with springs but only one would open and close. Need to partially disassemble and finish build these.
The video below shows the claw hand working and I tried to show the internals after assembly.
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