Alt-BEAM Archive

Message #08009



To: beam@sgiblab.sgi.com
From: Richard Piotter richfile@rconnect.com
Date: Thu, 25 Nov 1999 09:44:26 -0600
Subject: [alt-beam] Re: photowalker video & Quadrapod/Hexapod II legs


Nope. Not in this dinky little farm town. They don't even have
plexiglass! asked 3 places!

Richard Caudle wrote:
>
> Your local hardware store should have Lexan sheet in stock.
>
> Richard (the elder)
>
> ----- Original Message -----
> From: Richard Piotter
> To:
> Sent: Thursday, November 25, 1999 9:18 AM
> Subject: Re: photowalker video & Quadrapod/Hexapod II legs
>
> > Sounds interesting! Where can I order this material? I have to travel
> > out of town just to get plexiglass!!! I'm considering using a combo of
> > transparent material and the yellow sheets from Lynxmotion. I've worked
> > with Plexiglass and it is a little af a pain to mess with. If I can find
> > some, I'll have to try this Lexan material. Thank you!
> >
> > Of course, with the new saw, I might try to go with a few metal pieces,
> > if I can get the metal and the blades for it!
> >
> > Richard Caudle wrote:
> > >
> > > > > >If anyone knows anything about the Lynxmotion design, send it on
> over!
> > > > > >$200 is too much for me, and if I can do the same with less than
> $20 of
> > > > > >Plexiglass (CLEAR!!!), then I think it's work the extra work and
> > > designing.
> > >
> > > Don't use Plexiglass! It's too brittle and hard to work with. Lexan on
> the
> > > other hand is a miracle substance. You can even bend it without
> heating
> > > it! Just leave the paper on it until after you've drilled and bent it!
> > >
> > > Richard
> >
> > --
> >
> >
> > Richard Piotter
> > richfile@rconnect.com
> >
> > The Richfiles Robotics & TI web page:
> > http://richfiles.calc.org
> >
> > For the BEAM Robotics list:
> > BEAM Robotics Tek FAQ
> > http://people.ne.mediaone.net/bushbo/beam/FAQ.html
> >

--


Richard Piotter
richfile@rconnect.com

The Richfiles Robotics & TI web page:
http://richfiles.calc.org

For the BEAM Robotics list:
BEAM Robotics Tek FAQ
http://people.ne.mediaone.net/bushbo/beam/FAQ.html



8010 Thu, 25 Nov 1999 10:50:42 EST [alt-beam] Re: goldmine beam@sgiblab.sgi.com Blumojo13@aol.com http://www.goldmine-elec.com
blumojo13



8011 Thu, 25 Nov 1999 08:36:43 PST [alt-beam] Lexan beam@sgiblab.sgi.com "Timothy Flytcher" I have used Lexan (R/C bodies) and know some of the good things about it,
but what are the bad??? How dose it handle UV??? Is there a list of good and
bad traits???

>Your local hardware store should have Lexan sheet in stock.
>

______________________________________________________



8012 Thu, 25 Nov 1999 11:40:56 -0500 [alt-beam] Re: photowalker video & Quadrapod/Hexapod II legs beam@sgiblab.sgi.com Bob Shannon

Richard Piotter wrote:

> I opened up Quicktime Pro and exported your video to Sorensen 2 codec.
> It's 3.8 MB at best quality compared to about 4.5 MB for the Cinepak
> codec. Cinepak is a common codec, and is included in Quicktime. I
> recomend it, even if it's a little bigger (or a lot bigger). Good
> choice! I also LOVED the video! That thing looks strongly phototropic! Impressive!
>
> I just built a cardboard prototype of what appears to be a replica of
> the Lynxmotion Quadrapod and Hexapod II leg assemblys. If they are
> sucessful, I will port the designs on my web page, as soon as I can
> regain access to the server. I need to get my new password (I think).
> Hehe! 8 pieces for the basic structure, plus servos, servo horns (I
> think that's what they are called), and the hardware such as screws and
> nuts. I've got nearly everything figured out, except the mounting of the
> vertical servo and the bottom piviot.
>
> Does anyone here have a Quadrapod or Hexapod II from Lynxmotion? I'd
> like to know hopw the vertical servo and the bottom of the leg assembly
> is mounted and how exactly it's mounted to the body as well??? I guess
> nylon or aluminum spacers could be used for the bottom pivot.

I've got a Hexapod II.

If you build their kit according to the plan (I made some mods here) there is
a small bit of plastic stuck to the bottom servo. This bit of plastic has a screw
set into it that passes down through the bottom of the main chassis. A set of washers

and a self-locking nut hold the leg assembly onto the chassis.

So basically, in the early Hexapod kits (they have changed recently) the upper and
lower chassis plates are only connected by the legs themselves. This is done by
screwing the top plate to the leg pan servo horns, while the lower plate sorta hangs
off of the leg piviot screws at the bottom of each leg. The leg mounts themselves are

a sort of L-bracket with the pivot screw located directly under the leg pan servo
horn.

Lynxmotion has you mount this lower plastic plate to the bottom servo with mounting
tape. Its strong enough for the job, but I wanted something a bit more robust.

I attached the bottom bit of plastic directly to the vertical leg servo mounting plate

with epoxy. I replaced the lower leg pivot screw with a flat head screw, and recessed

this into the lower place, permanently attaching it with more epoxy. This put the
lower
pivot plate directly against the side of the lower servo and eliminated the mounting
tape.

(the lower servo is the vertical leg lift servo)

> If anyone knows anything about the Lynxmotion design, send it on over!
> $200 is too much for me, and if I can do the same with less than $20 of
> Plexiglass (CLEAR!!!), then I think it's work the extra work and designing.

Yep, I was tempted to copy the Hexapod II over onto aluminum plate! If you have
the time to make your own chassis parts you can save a lot of money. On the other
hand, if you have a good job its much nicer to send Lynxmotion the money so you
can focus on building the brains rather than the brawn. I find my time is much
better spend designing the electronics to go into the Hexapod than on trying to
duplicate the kit.

Butit would be very different if I had more time and less money!


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