Big Bot

[Brian]

This is my home-made bot, it turns and lifts. the elbo bends and turns.
the arm sits on electric whellchair base. the arm is made out of steel pipe
and extruded alluminum. Gears are boat hoist and boat winch both worm
type these are driven by timing gears from lawmower, 12V windshield wiper
and fan moter power it. Main lift is salvaged dish antena drive 36V. Swivel is
windshield wipper moter driving on ring gear. Main swivel bearing is axel off
truck with secondary bearing turned from alluminum.
I welded this up myself, bushings and bearings I made on 9" lathe. The design is one I have long thought of based losly on industrial type but more
attention to ballence because it is on whells not bolted down so it can tip over, moters to bend and turn elbo are in back of arm to provide ballence.
from Jax Fl
Brian

[Brian]

The picture?

[HarryBotter]

Brian, the way the forum has been set up, if more than one picture is attached only the paths are shown. If you'd like the pictures to be seen on the post itself just attach one picture per post.

[frank]

Hi Brian,

Nice large scale robot! I am working on a large arm as well and have a couple questions. Does the wiper motor on the ring gear bind at all or does it provide enough power? What kind of weight is on top? About what speed does it rotate at and does it wind down past the stop point? Do you use linear actuators on the arm? Again, excellent build!

[Brian]

Hi
I did have trouble with ring gear, to start with I set it on cardboard and drew inside circle, I then located center on cardboard. The ring gear is stationary , bolted to bearing . I measured distance across corners divided by two to get radis of circle, drilled holes slightkley oversize to allow fit.
before tightening bolts I carfully checked to make sure it was centered by holding a knife blade part which turns and looking for high spot and corecting.

The moter was chose for it runing slower than some of them. The small gear came off a lawn mower starter it is plastic and has screw shape on the inside to make it jump in and out of ring gear, unaceptable. I turned a bushing to fit and threaded to fit windshield wiper moter and used a little JB weld . It unscrewed going backward, The gear moter had a short shaft that was tapered with splines , I remade bushing with a coller so it would go over taper and thread on milled out inside out of round and reassembled using JB weld. Lining moter up with gear took more than one try, I was considering using a spring to hold gears togeter like on small bot friction drive but seams to work as is , on 12V a little slow but on 24V rather frighting. Speed controle ,the next step is neccesary because it is dangerious.

There are no linear actuators in big bot or small bot. Big bot is welded out of steel pipe , the gear that rotates elbo is heavy and on counter ballence end of arm, rear end is built around a sledge hamer for weight and strength.
Elbo bending is controlled by wind shieldwippermoter 2/1 gears turning shaft that goes through arm to elbo which is wormgear winch with cable removed and arm bolted in place to bracket welded.
Good luck , send pictures and thank you for the complement.

Brian