If anyone is interested, This is what I have been working on
last year-The saga continues into this year also, I am still tying up
a few loose ends.
I know many here dont give a hoot about humanoids or
bipeds, but take a look ! I dont have a regular website, and my
photograpy(besides being dated) is pretty bad, but I think you can get
the gist of it all.
That's very neat. I'd love more detail on how you make the resin parts.
Also, you should consider using robotics servos for the joints. They
can be a bit expensive, but not too bad -- an AX-12+ is $45 (including
some handy brackets), and offers 16.5 kg cm of torque, which is a lot.
It's very hard to come up with your own motors, feedback sensors, and
electronics to do what these servos do, with the same speed and
strength, for less money.
That may not be strong enough for a 4-foot-tall robot though. If
necessary, you can go to truly monstrous ones like the DX-117, with 37
kg cm of torque. That's going to set you back a lot more money, though
(like $150-$200, I think).
You might be able to get by with something like the AX-12+ for most of
the joints, and just double it up for critical ones like the knee. That
gives you twice the speed and torque of a single servo, and is a pretty
common trick on the Robo-One circuit. (Though your robot is a giant
compared to any of them!)
I got kinda hung up on using steppers in the eighties-The ones on this
machine are a buck each(on sale),regular 2.95. I can run the arms fast-
but the legs need to move slower for now as I am using no balance
system electronics. Right now it utilizes GOG(Grace of God) and
carefull tinkering with center of gravity.Servos are do-able! I
suppose some day I will have to get with the program.As is the whole
dern thing only costed about 300$ to get up and
I made molds for each of the joint parts so I can make what I need on
I hate tearing something apart to modify it, this way I can just slap
another limb together and make changes. I used mainly gearsets from
american science and surplus(4 gear set 1.95 each) fro the drives.
The resin parts I made from wood patterns-I coat them with about 40
layers of latex(letting dry between each coat). When the
latex(available online,Google for environmental tech products) is dry,
you pull the wood patttern out, and support the mold on the sides and
fill with resin. You can use fiberglass resin
from the auto store about 30$ a gallon. Then drill,tap, sand and paint
Higher quality resins can be had in epoxy or urethanes.
Its obvious I need to join a timewasters ten step program. But the
fun and entertainment value is priceless. I just got tired of "box"
robots with wheels,tracks etc. I had NO idea............
Joe-Thanks for the advice! you have me thinking.....
Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here.
All logos and trade names are the property of their respective owners.