Alright, proof of concept for robot arm fabricated with steel wire and car window wiper motors is a partial succes.
I wanted to make something like this:
but bigger, cheaper and stronger. partial result is:
It’s bigger and cheaper, not yet stronger…
my production process was:
- create a template for the wireframes with bolts to bend the steel wire around (hardboard in the background)
- cut steel wire to length
- straighten the steel wires by twisting them by clamping on end in a power drill and the other in a vise
- bend the wires around the bolts with a custom tool, to bend them close around the bolts and keep the rest of the length straight)
- spotweld the wires together with a diy spotwelder made with a re-wound microwave oven transformer.
- glue in a kind of nuts for the “bearings” using woodworking PU glue. This slightly foams and sticks well to zink-plated wire.
Learned a lot:
- the concept of keeping motors central and translating the motion through straight pieces limits the range. Thats’ probably why excavators for instance have hydraulic actuators near each axis
- my wireframe is square, because I tought moving the couplers inside was a good idea. Should have stuck with a triangle shape and keep the couplers outside. The arm twists when loaded because torsion forces can’t be handeled without colliding with the support.
- welding together the frame without a template is very cumbersome.really Next try I’ll make a cardboard mould.
- the motors take up a lot of current, over 30Amps! Purchased a shield base on the VNH5019.
- motors may be overrated. exessive speed, excessive power, exessive weight, excessive current. Cool however!
All and all I’m stil optimistic about the concept. however some changes are required to create something that may actually work…