Alt-BEAM Archive

Message #01085



To: beam beam@corp.sgi.com
From: Richard Piotter richfile@rconnect.com
Date: Sun, 28 Feb 1999 17:09:24 -0600
Subject: [alt-beam] Spyder Frame


I've finished the all but the motor linkages for my "Spyder" type robot. It's
much like Mark Tilden's Spyder. If you don't now what I'm talking about,
http://www.solarbotics.com has a nice, though small picture of Mark T's Spyder.
So far, this one is turning out nicely! I think I made the femurs of the legs a
little long, but I'll make up for it with a longer drive bar. Basicly, the motor
will have a bar attached to it, and the leg will then have a bar attached to it.
The two bars are joined together by a losely pivoting bar, so as one moves, it
pushes or pulls the other. If one is shorter than he other, it acts like extra
gear reduction.

I've only got the non drive mechanics complete. The frame is built, but the legs
aren't yet attached to any motors. The joints are polished brass hinges, though
that doesn't matter. They were just the cheapest, simplest, and most reliable
method of creating joints. The frame is cloths hanger wire (a LOT of it! Hehe!
:) and all connections are soldered. Also, The Hydrochloric acid based flux from
some silver solder kits at hardware stores is very nice for joining many metals.
Just don't use it for electronics, and wash it off if you spill any on you.

I'm not sure if I'll mount the motors for the lower leg on the body or on the
femur. If I mou it on the femur, the leg will not extend when lifted or dropped.
It'll remain where it is at. If I mount it to the body though, it'll keep the
leg at relatively he same angle as the leg lifts and drops.

I may also use springs instead of bars, to give the legs some natural
flexibility. I guess it just depends on what seems to work best.

I'll scan pics of it and my turbot which is also in the works when I get my
Power Macintosh G3 and the tuner/capture card for it (which is backordered).
--


Richard Piotter
richfile@rconnect.com

The Richfiles Robotics & TI web page:
http://members.xoom.com/richfiles

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