Mystery hole digging drop tool - GIF

[Jon]

Not even sure what this is called. Hole digging drop tool? Anyone know what's going on here?

[Oldjeepdog]

Not even sure what this is called. Hole digging drop tool? Anyone know what's going on here?

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A dynamic penetration tool, possibly for pilings or to break rocks in a borehole for a well. Nobody seems to be close to gather a measurement.

[Bony]

I reckon it works like an inverted umbrella, opens upon retraction and withdraws soil as it's lifted out of the hole. A small pile of soil can be seen briefly in the righthand background. Not suitable for rocky terrain!

[neilbourjaily]

Anti-bunker-buster testing

[Drew1966]

It’s a rock breaker.
Sometimes when you’re drilling a well, you hit rock that is hard enough to badly damage drilling tools. When you do hit such material, a dynamic rock breaker is used.
Given that this was filmed in China, where diesel piston pile drivers are used, it must be some pretty damn hard rock.

[Frank S]

I am wondering what kind of catch and release mechanism are they using there clearly are no electrical cables. The only thing to scale by wold be the block on the crane or the stabilizing tower struts. the block wold most likely be about 2ft across and 1 section of the struts wold be 10 ft this wold place it about 6 to 7 feet tall and possibly 30" in diameter.
It is obviously used for penetration through something What I wold have no idea nor wold I speculate the why of the operation. If they are simply using it to enlarge a bore hole then an overshot drill bit would have served that purpose if they are trying to break through a very hard strata then a 3 cone button bit with 20,000 to 30,000 lbs of drill collars would do that at about 135 RPM.
If their intent was to set piles then a hydraulic or diesel pile driver could do that as well.
the only thing I can think of for its use is to make a bore hole for piles or posts by the means of compaction. the slight amount of dirt we see would be just the amount that saw sloughed off the top of it when retrieving from the bore hole nowhere near enough to constitute a hole that had been previously bored by an auger or drill bit.
Most drop hammer drilling is done with a blunt elephant foot shaped bit attached to a long solid cylinder for the weight and directional stability.

[Elizabeth Greene]

There is a related technology called "Cable Percussion Drilling". It uses a tool dropped by gravity to cut through soft stuff and smash its way through rock. Then a winch (or people) lifts the tool and drops it again. The spoil is removed by a cable dropped cylinder with a flapper on the bottom. It's an ancient technology, going back thousands of years.

Making bits for this is a dead simple forging and welding job and a few bucks worth of scrap. The hard part is the winch mechanism or finding some people to pull the rope.

See also: Wellspring Africa's Hand Powered Percussion Drill

[Ralphxyz]

I wonder how the cable/hook is reattached in the hole.

The first well I ever worked on drill used a impact hammer/drill. Drilled through soil and granite to 200'

Ralph

[VinnieL]

Those well drilling techniques Ralph described are known as a "churn-drilled" well. Some people claim the wells are more stable and more permanent when drilled in that manner. My Dad sought out someone with an old churn drill rig to drill the one at our new house about 1970.

[Moby Duck]

Well, well, well.