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[DPRG] jbot twists off

Subject: [DPRG] jbot twists off
From: Kipton Moravec kmoravec at spectronics.us
Date: Fri Jun 24 17:01:53 CDT 2005

You could always move up to Titanium if the steel does not work.

I found my way to your home page, and your music page
http://www.geology.smu.edu/~dpa-www/music/index.html listened to your music,
and read the article by Lawson Tate about your band (combo?) BL Lacerta.
Lawson is the DMN Theater Critic and watches a lot of Delynda's shows.

I liked most all of your music, especially "Weather Channel", and "On the
Spot". However Delynda and I both missed hearing the baby cooing in "On the


> -----Original Message-----
> From: dprglist-bounces at dprg.org [mailto:dprglist-bounces at dprg.org]On
> Behalf Of David P. Anderson
> Sent: Friday, June 24, 2005 3:07 PM
> To: dprglist at dprg.org
> Subject: [DPRG] jbot twists off
> Howdy,
> jBot now has a working sonar array and can be let loose
> to run autonomously in dangerous places like the junkyard
> where this morning in the middle of a spectacular run
> over a pile of broken pallets and tangled metal pipes
> it managed to twist off the rear left driveshaft.  Plastic.
> Twisted it up like a piece of black liquorice and snapped it
> off at the ujoint:
> <http://geology.heroy.smu.edu/~dpa-www/robo/jbot/jbot_twisted_driv

So I thought, must be that we are putting a whole lot more torque on the
driveshafts than they are designed to handle, and headed off to the
hobby shop to buy replacements.

There the R/C car guy told me that the Nitro cars twist off their
all the time (which made me feel better), and he sold me a set of steel
velocity joints to replace the plastic driveshafts (so THAT'S how they make


An interesting sidenote for those contemplating using R/C suspension and
drive parts for an offroad robot.  Evidently designed for high speed
(35~40 mph) and low torque, while our robots generally tend toward low
speed (4~5 mph) and high torque, hence the broken driveshaft.  Seems to
be a problem that the R/C nitro guys have already neatly solved.   Just
send money... ;)

best regards,

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