In a message dated 3/8/2010 9:08:56 P.M. Pacific Standard Time,
ojaivalleybeefarm@dslextreme.com writes:
Do they have a zert
fitting on that ?
Hi Brian. I'm glad to see that interest on this device is still out
there.
After watching the actual device in use on the short video it looks
surprisingly simple. We've had some discussion on this before which got
me thinking.
First off, I'm thinking there would be some resistance to holding
the rod mechanism extended as the water pressure will be trying to push it
back into the sub. ( I remember this was mentioned before by someone
) Would a fixed sleeve with an inner threaded rod and sealing "O" rings
work to maintain extension of the rod ?
Operating the grabber pincers will require another rod with maybe a hand
grip inside the sub. This could be inside the threaded extension rod ( now a
tube)
I've done some rough sketches for various methods of grabber arms
and it's pretty complicated to make an arm. It looks to me that it takes a
minimum of 5 actuated joints to reach and grab in three dimensions.
Starting at the fixed base......there needs to be a swivel joint. Next is
a "shoulder" joint so the whole arm can go up and down. Next an "elbow" joint
to extend the reach, or a telescoping joint for the same. Next comes a " wrist
" joint that rotates the grabber "hand" so the grabber can operate
in two dimensions. Next is the grabber pincers, which at it's simplest is just
two fingers. ( three would be better. )
That's the five, and another joint at the wrist would be good for using
the pincers at various angles relative to the extended arm. ( total of six
)
I was thinking too that for the grabber pincers, it may work to use an
air cylinder so that the pressure applied to the "pinch" could be regulated.
Soft ( low pressure ) for picking something delicate or high pressure for
grabbing and holding something hard.
That's really the beauty of the "cue ball " idea. It swivels, extends,
retracts, rotates, and grabs with hand pressure. I think it would be very
intuitive to operate. If you've ever seen a mechanical arm in action,
it's slow, clumsy, and complicated.
It would be interesting to see some of the other guy's ideas sketched
out. Maybe we could bring some random sketches to the upcoming convention and
compare notes.
We called it "cue ball " but in reality a stainless ball is
probably the best material. Not sure how you'd make that part but I bet
a machinist would know how. Maybe it would be possible to use a ball valve
body and seals, modifying it to swivel all around instead of the two
dimensions it's designed for. ( just thinking out loud )
The "hand" that Phil Nuyten showed us was pretty damn cool. The guy's a
genius ! What an imagination.
Frank D.