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Anyone here help me with drop hammer design?

You didn't mention how many piling you need to set. Your location makes a big difference in the method used, is this fresh water or salt? Are you required to hammer these in or does the soil require it? The only reason to hammer these in is if you're building a boat house or gazebo. I doubt that's the case with only 4' of embedment.

The cost effective way to do this is to jet them in with a rental water pump. A simple Gin Pole temporarily mounted to your pontoon boat is all you need. You can locate the boat with ropes and anchors. Building leads and spuds that work well is more work than building a dock!

Jetting piling is extremely effective. My personal floating dock, small pier and bulkhead have survived 3 major hurricanes without budging or lifting.
around 30 pilings.. fresh water..required to drive no jetting..but i guess if they didnt see you..lol
 
About 35 years ago, I designed a floating pile driving rig for a friend. He was a marina operator, and needed to drive and pull fairly small diameter round wood piles for floating docks. This was on the Hudson River, and he needed to drive the piles as well as straighten them up after winter, and pull pilings to either rearrange floating finger docks or due to damage or winter ice. This fellow had an older drop hammer pile driving rig he'd built. It was on some kind of float. He wanted something more substantial and knowing I was an engineer with some familiarity with 'water work'. I had been temporarily reassigned to a job of laying a power transmission line on the bed of the Hudson River. The power transmission cables were to be run inside 10" steel pipes filled with insulating oil and laid in a trench dredged in the ribver bed. The marina owner helped us out with dockage for smaller work boats. We repaid the favor by clearing his marina slips of bottom silt using the screw of a tugboat. Wait for the tide to go downriver, set a couple of anchors and use the screw on the tug to blast the silt out of the slips. Handy way to avoid a lengthy process getting a dredging permit. The marina owner was a real character and we became pals. He wanted a floating pile driving rig built around a steel barge and a "Unit" crane. He owned the Unit crane, and it fell to my lot to design the barge, leads and the rest of the rig.

Since the OP has asked about a basic DIY drop hammer piling rig, I will try to describe the marina owner's homebuilt rig. The actual drop hammer rig consisted of a set of 'leads'- the vertical guides for the hammer; a drop weight; and a gasoline driven capstan (or 'gypsy head'). The rig was built of odds and ends of scrap and junk. The drop weight was a galvanized steel "range boiler", a 40 gallon hot water tank, filled with a mix of concrete and plenty of scrap steel. The leads for guiding the hammer were made of steel angle and welded together with cross-ties to create a track to guide the hammer. The drop weight, aside from being an old range boiler, had steel welded along two vertical sides. This steel had guides to run on the angle iron leads welded to it. The top of the vertical steel 'straps' on the range boiler/drop weight had a yoke welded to it for the hoisting rope. The bottom of the range boiler/drop hammer had a few pieces of heavy steel plate welded together, about the diameter of the range boiler. This formed the striking face of the drop weight. A single rope sheave (pulley) was on a mounting at the top of the leads. I am recollecting that the leads were somewhere around 20 ft tall. The hoist rope was hemp rope. The gasoline engine drove the gypsy head via sprocket chains to reduce the speed. There were also a set of 'fingers' or guides welded to the base of the leads. These formed a 'fork' to capture the wood pilings and hold them in line with the drop hammer. The hoist rope could be unhooked from the drop weight and used to handle the wood pilings. The other thing needed on any sort of floating pile driving rig are 'spuds'. Spuds are 'legs' which stake the barge or workfloat in position when setting up to drive piles or pull them. The workfloat had spud guides and the hoist rope was used to pull up the spuds. The spuds have cross-holes and are pinned off to hold them up when moving the piling rig. I believe the original homebuilt pile driving rig used some old steel pipe (4" or 6" if I remember right) with the bottom ends cut, folded in, and welded to form points. Spuds are often let to free drop and sink themselves into a soft bottom. Once a workfloat or barge has set its spuds, the spuds are not pinned or locked to the workfloat or barge. The spuds are held in spud guides or spud wells, letting the barge or workfloat move vertically as water level or the draft (due to changes in weight on the workfloat or pile hammer action)
changes.

I had never designed a barge or even a rowboat prior to my being asked to design the 'new' pile driving rig for the marina operator. It was a favor to a friend and a chance to get into a new aspect of engineering. I asked that he have a naval architect check my calculations and design and he agreed. We began by ordering a set of leads and drop hammer from a company advertising in either "The Construction Bargaineer", "Rock and Dirt", or "Boats and Harbors". All of these were sales listings printed on a yellow newsprint paper that we got via the US Mail. I sized the drop hammer and leads based on boom length and load chart for the whip line of the Unit Crane. The whip line is a single hoist rope. The Unit Crane had the feature of 'free spooling' to lower the whip line, with the operator relying on a band brake on the hoist drum to control drop speed or hold the load. The Unit Crane was 'on steel' (crawler tracks), so was compact and could be walked onto the new barge.

I designed the barge with bulkheads creating ballast tankage. I also designed piping and a manifold and pump (gasoline driven) to allow for ballasting and emptying ballast tanks. When pulling pilings or lifting loads, any floating crane or derrick barge wants to sink on the side where the load is happening and come up on the opposite side. I'd been on enough floating crane, bucket dredging and other work barges to know that much. I also designed spud wells and spuds, along with spud gates to lock the spuds when raised. We went to s shipyard working on steel barges and similar with my drawings. They had some material in the yard from some caissons used on a bridge project. Good steel plate with longitudinals (stiffening members) welded on. I adjusted my calculations for the heavier thickness of plate and stiffeners (which changed the barge length slightly, width being fixed to fit in between the marina docks). The shipyard naval architect reviewed and approved my calculations and plans, and the barge was built. Crane barges often approach a square shape if the crane is to swing on its turntable. This little barge was more of a narrower rectangle for what it had to do. I asked my friend to weld stops on the crane's turntable to avoid rotating too far to port or starboard and risking capsizing.

The little barge was moved using a gasoline driven winch. This winch had one hoist drum spooled with maybe 5/16" or 3/8" wire rope, and a 'gypsy head'. Either of these were used to pul the barge into position for pile driving or pile pulling. For transiting the barge from its storage slip to the finger docks, an outboard motor was used. There was no rake or fine lines to the hull of this barge. It was a blocky scow, designed to provide a stable (or relatively so) platform for the Unit Crane and piling leads.

BTW: a bit of simple high school physics applies to drop hammers, as well as wood splitting malls, axes and hammers. That is the basic equation for kinetic energy. KE = 1/2 MV*2 where M = mass of a drop weight (or hammer head, maul, etc), and V = velocity. Since kinetic energy varies as the square of the velocity of the mass dropped (or swung if considering a hammer or maul), it is "V" that really ramps up the kinetic energy produced by a drop hammer. The acceleration on the planet earth, due to gravity is "G", which is 32.2 ft/sec-sec. Using G and the height of the drop (or leads that guide the drop hammer), V*2 = 2 G S where S = height of the leads. The asterisk * is used to indicate that a number is squared. If we go back to HS physics, the teachings often assumed an impossibly perfect set of conditions with "frictionless" and "no air resistance" being given to allow the use of these basic formulas. Obviously, there is a limit as to how tall a set of pile driving leads can be built, and the guides for the drop hammer will have friction to slow the drop hammer's fall. In actual use for the simplest drop hammers, a few turns of hemp rope (or similar) are taken around a capstan or gypsy head. The gypsy head is constantly turning when driving piles. The operator pulls tension on the slack end of the hoist rope when he wants to raise the hammer. This causes the rope to bind around the gypsy head. When the hammer reaches desired height in the leads, the operator lets the rope slip in his hand. The rope slips thru his hand and the weight falls. Not so fast as gravity would make it happen under ideal conditions- there are friction components. The operator knows NEVER to wrap the hoist rope around his hands. For lifting the drop weight, close your hand around the rope and get a little tension on it. The rope will bind around the gypsy head and lift the drop hammer. An electrician's cable pulling capstan (Greenlee makes them) will give some idea of this sort of thing.
That is an amazing story, thank you for taking the time to give all the detail. I’ll never drive a pile as long as I live but I greatly appreciate the insight into design/execution of a random engineering project.
 
Trent:

The youtubes you watched of drop hammer pile drivers may have been showing a rig with a winch built for the purpose. I.E., that one long lever controlled the clutch and band brake on the winch spool. Pull up on the lever and engage the clutch/brake off, and raise the drop weight. Get the lever into 'neutral' position and the clutch disengages/brake off, and drop weight pulls the hoist rope off the winch spool (free spooling). About the instant the drop weight connects with the 'helmet' on top of the pile, the operator comes down on the lever to apply the band brake. This was to keep the winch spool from continuing to spin and 'bird's nest' the hoist rope on the spool. This sort of arrangement of clutch and band brake was fairly common on winches used in some hoisting applications. The capstan is about the simplest way to get this same action, but the operator has to be constantly working the hoist rope on the capstan.

I am not so sure about using a pontoon boat as a pile driving barge or skow. I suppose it would work for a light drop weight and relatively low pile driving leads. My sense of it is that the pontoon boat, if it is a basic recreational type, will have a fairly high center of gravity to begin with. The recreational pontoon boats that I've seen are designed with a very shallow draft to allow people to run them into shallow water or beach them without incident. Not a particularly heavy framing on the deck spanning the pontoons. We had pontoon boats to ferry men out to the crests of some of the hydroelectric dams, and we used recreational type pontoon boats. The crests of the dams had a relatively flat top, being the spillway for the dam. It was a 'bullnose' with a very large radius. When we'd put men on the dam crests to set or remove flashboards, we'd pull the water level down a bit below the crest of the dam. The pontoon boat could run right up to the dam crest and the raked bows of the pontoons would actually be resting on the crest of the dam. While my experience with pontoon boats is very minimal, they strike me as a bit light for handling a drop hammer pile driving rig and the high center of gravity is only going to get higher as you add a set of pile driving leads made of angle iron and maybe 15-20 feet tall. The aluminum of the pontoons seemed quite thin when I rapped it with my knuckles. I believe some pontoon boat manufacturers fill the pontoons with closed cell foam for buoyancy in case the aluminum skin of the pontoons is holed (as in running hard aground on rocks). The pontoon boats I saw on jobs had aluminum extrusions MIG welded together for the deck framing. Also on the light side for structural strength. Welding spud wells or spud gates to the pontoon boat may be a bit difficult.

If you do go thru with this idea of using the pontoon boat, make sure to wear a life preserver and work in warm weather so going into the drink won't be so bad.
 
In soils testing a common process is the Standard Penetration Test. That is a drop hammer using a 140 pound weight. Maybe look at scaling that up.
 
The old soil testing rigs I remember seeing used the capstan and hemp rope to raise/drop the weight. These rigs had an "A" frame with sheave (pulley) at the apex or point, and it was raised and guyed off to the frame of the soil testing unit. This was a gasoline driven winch, which could have been on a skid, or on a truck bed. The later soil testing rigs are on self-propelled crawlers.
 
With a doll head on the end of a winch shaft (many old cranes had these too) ,you can throw four turns around the doll head ,and by a simple pull on the line (hand pull) raise and drop a weight for pile driving.......hemp rope /plastic ,not wire.
 
In soils testing a common process is the Standard Penetration Test. That is a drop hammer using a 140 pound weight. Maybe look at scaling that up.
Yep- I repair ours on a semi regular basis. Although we have a much larger one which uses a 480 lb weight dropping 30 inches, 40-45 drops per minute. We do not take samples with it any more, (they did before my time here) they just pound a rod in until it quits moving, and then measure the "skin friction" pulling it out. The sampling takes place separately. Copying it would not be "cheap", LOL.
Although, we are having a new one built and this one will ultimately be auctioned off...
 
The old soil testing rigs I remember seeing used the capstan and hemp rope to raise/drop the weight. These rigs had an "A" frame with sheave (pulley) at the apex or point, and it was raised and guyed off to the frame of the soil testing unit. This was a gasoline driven winch, which could have been on a skid, or on a truck bed. The later soil testing rigs are on self-propelled crawlers.
The old timers tell me you could tell who had to "throw the rope", as those guys had huge right arms.... :D
 
When I was a kid on the farm we had a post driver which mounted to the 3 point hitch and ran on hydraulics. Noisy SOB, but you may find a used one on a farm sale...
 
John.k

You are describing precisely what I'd suggested. In this politically correct world, the traditional name(s) for what you call a 'doll head' will land a person in deep s-t if heard by the PC police. In the USA, "gypsy head" was the sanitized version of the original slang name (which used the "N" word). Either way, we are talking about the same thing. Plenty of cargo handling winches on ships had the gypsy (or doll) head on the drum shaft. A hemp rope was used for handling light loads as well as for a tagline to drift a load over from the centerline of the point of the boom. The oldtime riggers and machinery movers used a single-axle truck with a 'beavertail" on the bed ( the rear most portion of the truck bed curved or sloped downwards). These trucks had a vertical shaft with a gypsy head abaft of the cab. Hemp rope was used with a few turns around the gypsy head. This could be used to pull loads horizontally, or the rope was broken thru a snatch block or two or three to hoist or lower loads. By snubbing the rope around the gypsy head, a load could be lowered in a controlled manner. Nowadays, words like "gypsy", "beaver", and "snatch" are all potentially trouble with the PC police. Seen it in my last years of work at the NY Power Authority as corporate dreamed up ever crazier and restrictive policies, making what had been a happy and free-wheeling workplace at the powerplant into a minefield.

Getting back to the OP's post, I know a gypsy head or homemade facsimile was sometimes attached to one rear axle of a car or truck. The other wheel, on the ground, was chocked. The vehicle wads put in reverse or first gear, not so much for torque but slow rotational speed. Idle speed was raised (if the vehicle did not have a hand throttle) and a means of hoisting was had.
 
John.k

You are describing precisely what I'd suggested. In this politically correct world, the traditional name(s) for what you call a 'doll head' will land a person in deep s-t if heard by the PC police. In the USA, "gypsy head" was the sanitized version of the original slang name (which used the "N" word). Either way, we are talking about the same thing. Plenty of cargo handling winches on ships had the gypsy (or doll) head on the drum shaft. A hemp rope was used for handling light loads as well as for a tagline to drift a load over from the centerline of the point of the boom. The oldtime riggers and machinery movers used a single-axle truck with a 'beavertail" on the bed ( the rear most portion of the truck bed curved or sloped downwards). These trucks had a vertical shaft with a gypsy head abaft of the cab. Hemp rope was used with a few turns around the gypsy head. This could be used to pull loads horizontally, or the rope was broken thru a snatch block or two or three to hoist or lower loads. By snubbing the rope around the gypsy head, a load could be lowered in a controlled manner. Nowadays, words like "gypsy", "beaver", and "snatch" are all potentially trouble with the PC police. Seen it in my last years of work at the NY Power Authority as corporate dreamed up ever crazier and restrictive policies, making what had been a happy and free-wheeling workplace at the powerplant into a minefield.

Getting back to the OP's post, I know a gypsy head or homemade facsimile was sometimes attached to one rear axle of a car or truck. The other wheel, on the ground, was chocked. The vehicle wads put in reverse or first gear, not so much for torque but slow rotational speed. Idle speed was raised (if the vehicle did not have a hand throttle) and a means of hoisting was had.
The last fellas to run the old machine said "cathead"....
 
Is this for a one time thing or is it going to be a business? If the latter then I would save pontoon boat for a party barge and look at auctions or other dispositions for a FlexiFloat or similar section. These are used by contractors when it is necessary to work in shallow water or when the water cannot be accessed by water. These are sections usually 8' wide and 40' long. They connect together to make a barge that will hold a sizeable crane and still draw very little water. For your purposes it sounds like one would do the job. You would have a steel barge drawing mere inches and truckable to other jobs if needed. You could weld deck hardware and feet for a boom. You would need a bulkhead at one end to make a tank for counterweight.
 
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tdmidget:

I've been on a number of jobs related to hydroelectric work where we used Flexifloats. One job was a kind of 'bootstrap" operation. There was a public dock a couple of miles from the dam where the work was to take place. The contractor needed to put an American lattice-boom crane, on steel (crawler treads) onto a barge to get to the work site. To do this, they brought the crane on a low boy, along with a smaller hydraulic crane. This hydraulic crane was on rubber, and was driven over the road to the public dock. The hydraulic crane handled the boom sections of the American crane to assemble them. Flexifloats were delivered by flatbed semi, and put into the water with the cranes. As I am sure you've seen, Flexifloats have built in locking mechanisms. This enabled them to be made up in any configuration to suite the work. There are also spud gates that use this locking system if I recall correctly. The contractor had a small push boat that was truckable. This had three John Deere diesel engines in it, and had pusher knees. The American crane offloaded the tug and put it into the water. It faced up to the flexifloats to push them along. Timber crane mats were also delivered to the dock. The American crane, having the reach, decked the flexifloats with the mats. One longer pair of mats was made up as a ramp from the dock to the flexifloats. The operator on the Amertican crane was a man well into his 70's. He walked the American crane onto the ramp and onto the flexifloats. The crane nosed at some seemingly impossible angle, the side of the flexifloats at the toe of the ramp seemed to be nearly submerged, but that operator was unfazed. He walked the crane onto the flexifloats while some us were kind of holding our collective breath. Once the crane was positioned in the center of the deck of the flexifloats, things were on an even keel with a nice but not excessive amount of freeboard. It made a good stable platform for the crane. The pusher tug then took the rig upriver, thru a canal lock, and over to the side of the dam and forebay of the hydro plant where our job was. I've seen flexifloats made up in a 'hollow square for one job, in an "L" to provide a floating access platform for work on a flow control structure, and a few other applications. One contractor used an old "Harbormaster" marine propulsion unit (a forerunner of the inboard/outboard used on pleasure craft) to move assembled flexifloats to and from the work.

Flexifloats are heavy, but as you note, they are shallow draft and quite adaptable. On some of the jobs, the contractor would put a "Conex" box (similar to ocean freight containers) or two on the deck. This provided storage for tools and supplies as well as a change shack for the crew. I would imagine flexifloats are available as used equipment, so might be an option for the OP if he has to do pile driving and 'water work' over the coming years as a regular thing.
 
Is this for a one time thing or is it going to be a business? If the latter then I would save pontoon boat for a party barge and look at auctions or other dispositions for a FlexiFloat or similar section. These are used by contractors when it is necessary to work in shallow water or when the water cannot be accessed by water. These are sections usually 8' wide and 40' long. They connect together to make a barge that will hold a sizeable crane and still draw very little water. For your purposes it sounds like one would do the job. You would have a steel barge drawing mere inches and truckable to other jobs if needed. You could weld deck hardware and feet for a boom. You would need a bulkhead at one end to make a tank for counterweight.
this is just for me. No buisness..
 
jmm03:

The youtube shows a DIY Thai vibratory hammer. The questions are:

-does the music played influence penetration speed ? When driving piles with a vibratory hammer, we measure penetration speed rather than taking a blow count to
get some idea of what the subgrade soil conditions are.

-the soil where this youtube was taken is likely quite soft for the pile to penetrate with the 'vibratory hammer' they used. 6 or thereabouts not-too-husky men might
weigh 120-140 lbs apiece, so at most they had 840 lbs of weight on the pile. Add the vibratory effect from the jiving and dancing and it is still a very light 'vibratory
hammer'. The pile looked to 'run under the weight of the hammer' with little, if any, additional 'energy' from the guys jiving and dancing needed.

-that begs the question: is the pile going to be driven to refusal (hitting some solid strata like ledge rock or well-consolidated clay soil) ? If they are going to simply drive the pile to its full depth with the conditions shown in the youtube, I doubt there is much friction bearing between the soil and the pile. Not much load bearing capacity in the pile shown in the youtube. Probably not much of a structure is going to be founded on those piles, maybe relying on them to keep a lightly built small building from
being blown away or washed away in the monsoon season.

When I first saw the youtube, I thought it was one of the Pakistani 'bore well' youtubes. The Pakistanis use similar methods to sink casing pipe for water wells. Soft soils, no rock, so these methods work.
 








 
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