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.
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