Robot arm with mobile hand and fingers, inspired by Terminator movie.
Welded mainly from various car parts. I was aiming for Mad Max style, rather than clean and sterile T800 look.
- angle grinder
- MIG welder (I've used MIG, but it would probably be easier with TIG)
- bench grinder
- metal files
- sheet metal cutters
Step 1: Gathering All the Parts
- piston and pins
- steering rack
- inner part of shock absorber
- clutch slave cylinder
- tripod joint (instead of universal joint)
- bearing from car gearbox
- 606 and 626 bearings
- pieces from other various bearings
- shift forks
- engine valves
- valve guides
- valve rocker arms
- timing chain
- spark plugs
- heim joints
- nails, screws & nuts
- sheet metal (~1mm thick)
Step 2: Palm
The static, base part for each finger is made from valve, spark plug (with cut off terminal) and heim joint.
Index, middle and ring finger bases are the same.
For pinky, I've used smaller heim joint. The thumb will be made a bit later.
The valves were nonmagnetic, but welded just fine.
Step 3: Fingers, Base Section
Rocker arm and valve guide create base part of finger.
I've used a screw with a welded nut in each of the heim joints and bearings as a hinge.
Thumb is a bit different, I've used smaller spark plug with the tip cut at an angle, different type of heim joint and shortened valve. Also instead of valve guide a piece of gear fork is welded at the underside of rocker arm.
Step 4: Fingers, Middle Section
This part involved welding a lot of bearings.
It was a bit tricky - two 626 bearings locked due to heat and had to be replaced with pair of 606s.
I've used inner races of scrap bearings as a decoration of valve guides and as a mounting point for the hinges.
Step 5: Finger Tips
Each finger tip is welded from four pieces cut out from sheet metal.
Pinky's tip is a bit smaller and thumb's a bit wider.
Step 6: Assembling the Hand
Finally the hand could be assembled.
I've joined faces of valves with heavy welds.
To add structural strength, I've also welded section of timing chain joining finger's bases.
The thumb will be placed opposite to the rest of the fingers.
At the beginning I didn't know how big the hand will be - it's almost twice the size of my hand...
Step 7: Making It More Human
Fingers were flimsy and had unnatural range of motion.
To fix that, I've welded stops (rollers from bearing, bent nails and stripes of sheet metal) for each of the joints.
The stops on the underside had to be made together with the spring hooks.
Step 8: Springs & Magnets
I've used washers as the hooks for the springs.
This step took a lot of time as the springs and hooks needed adjusting.
In relaxed state there is a bit of tension on each spring so the fingers don't flap around freely.
The magnets (glued on a bit later) allow the fingers to grip and hold something metal.
Step 9: Wrist
I've welded additional valve heads to make the hand and wrist joint stronger.
Another section of timing chain was used to join the thumb with the palm.
The wrist is made from tripod joint and big bearing.
The hand is welded to the outer race. I've used scrap inner race as a spacer between the bearing and the tripod joint to make space for heim joints.
Two trunnions had to be grinded because hole in heim joints I bought was 2mm smaller.
To springs attached on the circumference restrict the rotation of the hand.
Step 10: Forearm
Three parts join the wrist and the piston:
- inner part of scrap shock absorber
- steering rack with fragment of housing
- inner tie rod end and clutch slave cylinder
There is a spring inside shock absorber and steering rack housing, so they act as spring-actuators.
Step 11: Final Assembly
Piston was made from some kind of alloy and weld just didn't stick. I've tapped two holes and used the nuts as the mounting point.
Clutch slave cylinder housing is attached to the piston with pieces of shift forks.
I've used large nuts to connect bottoms of both spring-actuators to the pins.
Pins are joined with couple of spot welds, but can still rotate freely inside the piston.