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Lifting and Handling

The density of materials can be given in pounds/cubic-foot, kilograms/cubic-meter, or in "specific gravity". The last of these, specific gravity, is just factor by which a volume of the material is heavier or lighter than the same volume of water. This is very handy, particularly if you use the metric system, because the metric system uses water as the basis for measurements of weight. One cubic centimeter of water weighs one gram; a cubic 10-centimeters is a liter and weighs a kilogram; a cubic meter, is 1000 liters and weighs a metric ton.

The specific gravity of the carvable stones ranges from about 2.4 to 3.0, i.e., a given volume of stone weighs a little less than three times as much as the same volume of water. Some stones are a little lighter, some a little heavier, and they vary even within stone types, but you will not be far off if you estimate most stone, e.g., marble, limestone, and granite, at 2.7, and the iron rich, mafic stones, such as basalt and diabase, at 3.0. Water (and therefore, a person30) has a density of about 62 pounds per square foot, versus about 2.7 x 62 = 170 pounds per cubic-foot for stone.

Using these facts, it is easy to estimate the weight of any rectangular block stone. The volume of a rectangular block of stone is length x width x height. If you measure in inches, you can convert to cubic feet by dividing this by the number of cubic inches in a cubic foot, 1,728. If you know the density in pounds per cubic foot, multiply accordingly. If you know the specific gravity, multiply the volume in cubic feet times 62 times the specific gravity.

A useful trick for estimating smaller irregular stones is to compare it to a volume of water or something of similar density. A gallon of water weighs eight pounds, so a piece of stone the size of a gallon plastic jug of water will weigh a little less than 8 * 3 = 24 pounds. If the stone is about the size a five pound roast beef, it will weight a little less than fifteen pounds. A cubic yard of stone will weigh about 2.7 times as much as a cubic yard of water. There are 27 cubic feet in a cubic yard, so it will weigh about 27 x 62.4 x 2.7 or 4,549 pounds, which is about two and a quarter tons.

Even a small piece for a bust, say, three cubic feet, will thus weigh about 500 pounds. How does an artist handle masses like that without a crew? It's actually not that hard using some scrap lumber and a few basic tools. This section will give you a basic bag of tricks that can be used in many situations. Just remember Murphy's Law: "If something can go wrong, then sooner or later it will go wrong," and don't be under or between heavy things when it does.

Egyptian Style

If you have a strong floor, moving blocks of up to a ton or two around the room is easy, even when working alone. You need a crowbar, some pipes, and some scrap lumber. The process is illustrated below

  1. A person of average weight can easily tip a one-ton block with a crowbar or wrecking bar. If you're not heavy enough either get a longer bar or extend the one you have by slipping a longer length of pipe over it. If you can't get the tip of your crowbar under the stone, try driving hardwood wedge under it to get that first fraction of an inch. A pipe or piece of two-by laid on the floor can serve as a fulcrum if the natural fulcrum of the tool is too far from the tip. (Always place stone and other heavy objects on wood slats rather than directly on the floor.) Shim up the opposite side as well before proceeding, because it will be harder to get the crowbar under later.
  2. Crowbar it up enough so that you can kick a piece of scrap wood under the edge. Very important: never hold the wood or pipe in such a way that your fingers are ever under it because if you accidentally set the stone down you will crush your fingers. Drop the wood on the floor and push it under instead. No exceptions ever!
  3. Repeat with thicker wood under both crowbar and block until you can get a length of pipe under it.
  4. If the stone isn't too big, you can put the pipe near the middle, remove the wood, and teeter-totter it onto a second pipe. Be extremely careful doing this if there is any danger of getting your hands between the stone and anything else, such as the wall or another block. Again, you can easily lose fingers that way.
  5. If the stone is too heavy for that, lift the other side onto wood blocks until you can get the second pipe under it.
  6. It's better if the piples are not perfectly parallel at first because this will reduce the tendency to roll. When you're ready to roll you can shift the pipes around hitting them with a mallet.
  7. Once the stone is sitting on the pipes, you can either roll it in the obvious way, inserting a third pipe in front each time the stone gets close to rolling off, or you can skid the stone sideways in the direction of the pipes. The latter takes more work, but it's easier to control. If the stone is too heavy to simply push it along the pipes, shove a crowbar a few inches under it at a low angle and lift to shove it along.
  8. You can make a turn either by skidding the block onto a new set of pipes or by reorienting the pipes.
Moving a block on rolling pipes.

A block on rollers can only get away from you by half its length, at which point the front will tip and wedge itself against the floor. The other pipe will be near the tipping point, so it's easy to tip it back up. You can limit the motion of the stone by putting either the crow bar or a piece of two-by-four against the floor at a sharp angle in front of the stone. With this technique you can control even a multi-ton stone.

You can easily punch a crowbar through the planks of a wood floor, even if the floor as a whole is plenty strong enough to hold the stone. If you working on a wooden floor, use a wooden plank to lever on. It should be perpendicular to the joists (which are usually at right angles to the direction of the floor boards) and long enough to span two of them.

If you aren't sure that the floor is strong enough, a standard engineering manual (any library will have one) will give you the bearing strength of the floor based on the size of the joists, the distance they span, and their spacing. If you are on a first floor, temporary columns from the basement floor to mid-span will strengthen the floor enormously. Tubular steel columns with pins and screws that allow them to extend to the exact height needed are available at any lumber yard, but steelis only worth the cost for permanent installation; if it's just temporary, you can use 2x4's, 4x4's, or similar lumber.

If you are using 4x4's, cut a piece out of the post that is the width and depth of the joist and nail or screw it to the joist so that the weight is sitting on the end-grain exposed by the notch. Alternatively, cut one 2x4 long enough to sit directly beneath the joist, and nail it to a longer one so you can nail or screw it to side of the joist. Use a construction screw or a 10d nail every six inches to fasten the 2x4's together, plus two or three through the longer 2x4 and into the joist.

If the post is not quite long enough, snug it up by driving two roofing shingles under it, from opposite sides, to wedge it more tightly.

Another thing that makes a floor stronger is "bridging" between the joists. Bridging keeps joist under load from twisting, which makes them stronger. Bridging should already be present, but if it is not, you can either buy and install ready-made steel bridging, or simply fasten a 1x4 spanning across the joists from the underside, and screw it to each joist with three construction screws.

Another consideration on a wooden floor is the strength of the flooring between the joists. A heavy stone can break the floor boards between the joists even if the floor as a whole is strong enough. For heavy stones, you should place two-by lumber perpendicularly to the joists under the load to spread the weight.

Rolling the Block

Now that you've got the block where you want it, you will want to lift it to a convenient height for working. The process is illustrated below.

Rolling a heavy block up an incline.

If you only need to lift a block a little, use the technique described above to lift it onto wooden blocks instead of pipes. Two-by-fours or four-by-fours can be laid across each other several layers deep. Toe nail the supporting lumber together for safety, so it won't shift when you move or turn the stone. A bed of 4x4's is good up to a foot or so. Rough 6x6 or 8x8 shoring lumber is good for higher platforms, and is very cheap (it is usually green so expect it to shrink.)

If you want to get onto a higher bench than that, the following technique can be useful. You need a pair of heavy timbers to use as a ramp--old floor joists are great for this. The stiffness of wooden board is proportional to the width multiplied by the cube of its thickness, so thicker is a lot better. One plank probably isn't wide enough to use as a ramp, so fasten two together side-by-side by screwing wide pieces of plywood or strong lumber to the back. The two planks don't have to be touching-- you can space them apart for greater stability.

One trick for getting the stone up the ramp is illustrated above. You roll the stone up a ladder of blocks spaced so that as the stone rolls over a block, it is close to it's tipping point just as the leading edge touches the ramp. Try this out on with the planks flat on the ground before trying it on a ramp.

Whenever you're using a ramp, be very sure it is fastened securely to the trestle or work surface you intend to place the stone on, and be sure the entire construct is secure and immovable. Placing the trestle against the wall is ideal. Fasten the ramp the trestle or work surface with the soft iron strapping sold for hanging plumbing pipes. The strap is one inch wide, and comes in a roll, pre-perforated for bolts or screws. Screw it to the ramp and the table with construction screws or nail it with concrete-form nails (they have double heads to make them easy to pull out again when the form is dismantled.) This is not shown in the illustration.

If the block is too big to roll by hand, or does not have a square cross section, a come-along or block-and-tackle can be used to drag the block up the ramp by brute force. If the stone is not not too heavy, you can wrap the chains directly around the block on all sides, like tying a package, hook the come-along to the chains, and just drag it up the ramp right on the chains. Chain can be connected temporarily using carriage bolts, nuts, and heavy gauge washers. Use bolts that are at least as thick as the links.

A steel eye ring attached to the wall several feet above the workbench surface is a great permanent feature for the studio. If it's anchored with expanding anchors, it has to be placed so that the direction of pull on it will not be close to straight out, but at least partly from the side. The ring in my studio is attached to a 3/4 inch threaded rod that sticks out two inches, and extends through the wall, so that it cannot be loosened or pulled out from any direction.

For heavier blocks, you can make a temporary sled to drag it up the ramp on. If you can find a shipping pallet of the right size, you can just nail a piece of plywood to the bottom. Rub bar soap or bees wax on the bottom to grease it. Lash the block to the skid with rope or chain, and attach the winch hook directly to the lashing.

Be sure the work surface and the ramp are strong enough and cannot be pulled over. You can reinforce them with temporary 2x4 reinforcement if necessary.

Block-and-Tackle

This traditional rig, seen below is useful for directly lifting moderate loads. It's a system of rope and pulleys that gives you mechanical advantage by exchanging distance for force. A rope over a single pulley gives no mechanical advantage, just a more convenient orientation of the lifting force. The block and tackle employs many loops of a single rope to draw two sets of pulleys together. To draw the pulleys together one unit of distance, you must pull one unit of rope for each of the lengths of rope that connect the pulleys, thereby increasing the pulling force in proportion.

A block-and-tackle is elegant, but bulky, and requires a lot of rope, but you might find one at a yard sale. House painters often uses them for haning scaffolds.

Block-and-tackle with a 5:1 mechanical advantage.

Chain Fall

A chain fall,illustrated below is similar to a block and tackle, but it works with chain instead of rope, and uses gearing, rather than pulleys to obtain mechanical advantage. They are typically hung up high, either rigged to roll along a beam or simply hung on a hook. They are rated at anywhere from five hundred pounds to several tons.

A typical small-capacity chain fall (one ton)

An extendable chain with a hook on the end hangs down from the metal block that houses the gearing. A manually operated chain fall has a second loop of chain that the operator pulls on to turn the gears. By pulling the loop of chain in one direction or the other, the hook can be slowly raised or lowered. They are also available with electric or pneumatic power instead of the loop of chain.

Unless your chain fall is mounted on rollers from an I-beam, you'll only be able to use it to lift stones onto and off of dollies and other rolling platforms.

Make sure the attachment is solid--a loop of chain around an existing beam is good. Fasten the loop of chain with appropriately sized bolt and washers. For heavy lifting, overhead beams can be temporarily shored with a metal columns or four-by-fours. And once again, stay back. Don't be anywhere where you can be hit by either the stone or the chainfall if something breaks.

Come-Along

A come-along, shown below is an inexpensive portable winch driven by a manually operated lever. There's a hook on one end for attaching the rig to some stationary object, and a long cable with a hook on the other. A lever is used to wind the cable in and out, and a system of pawls allows the cable to be ratcheted in either direction, depending upon how you set the control switch. They don't look like much, but even the lightest duty come-along will easily lift 1000 pounds, and the big ones are rated up to five tons.

A two-ton come-along.

In the studio you can use them for dragging stones around the floor or up and down ramps, or for lifting stone directly onto a platform. Be very careful when using one to lift, because it's inherently hard to operate from a safe position. You need to be safely above the level of the stone. Also, be aware that the maximum rated load for lifting will be lower than for pulling. Also beware that a cable snapping under these kind of loads is dangerous in itself, apart from the unexpected release of the load, so do not exceed the rated load, and if the cables are worn, or the mechanism seems damaged, chuck it and buy an new one.

A two-ton come-along costs about forty or fifty dollars. Notice that the one pictured has an extra pully on the cable end hook that doubles the mechanical advantage. This feature does not appear on every come-along, but is nice to have.

Engine Pulling Hoist

An engine hoist, show below is a small, lightweight hoist used by mechanics to lift engines from automobiles.

A typical two-ton engine pulling crane.

Depending on the model, they're good for up to two tons and usually operate hydraulically. They have a lift a hook suspended from the end of an arm that's long enough to reach to the center of the engine compartment--plenty of distance to place a fairly large work block on a supporting structure. They have long feet to slide under the car or bench to keep the base beneath the hook. A new two-ton engine pulling crane costs about four hundred dollars, but you can often find them used on craigslist.com or eBay.

One thing to beware of is that the chain attaches to an extendable arm. You can only lift the full rated capacity with the arem all the way in. The farther out you extend it, the less you can lift. The manual that comes with it will give the exact capacity for each degree of extension.

Hydraulic Work Stand

A hydraulic work stand is a fantastic studio accessory. The stand shown below will lift a thousand pounds to a working height of up to 36 inches.

A heavy-duty lift table.

Prices for lift tables vary wildly for some reason. The one shown sells for three hundred dollars online. Very similar tables with the same rated capacity sell for as much as twenty-five hundred dollars.

Lazy Susan

A lazy Susan turntable with bearings is ok for modeling in clay, but it isn't good for carving stone. You really don't want hundreds of pounds of stone moving too freely; it's dangerous and it makes it hard to work.

A better solution is to set the block on a round or octagonal piece of plywood, instead of directly on the bare bench. For up to a few hundred pounds, this will reduce the friction enough that you can shift the stone by hand. Soaping the bench top, or rubbing bee's wax on it first will reduce the friction further. Formica, melamine, or masonite, laminated to the side facing the bench, reduces the friction much further, but be careful, as it can reduce the friction to to the point of being dangerous.

A large screw or lag bolt, through the center of the plywood and into the bench will constrain the motion to rotation, making it much safer. A C-clamp can be used to lock the turntable in position while you are working.

Cradles

An adjustable wooden cradle

Cradles, an example for small pieces is shown above, are good for holding work in the right position. This one has plank sides and hardwood slats, make working on pieces at odd angles easier. Two-by-ten fir or pine off-cuts make good sides. Great stock for slats can be had from the discarded futon bed frames that people are always throwing out.

For larger pieces, nail a cradele together out of 2x3 hemlock or fir. If the front edge projects downward half an inch or so, it can be allowed to hang over the front of the work bench to prevent the workpiece from sliding to the back of the bench.

Alternatively, pairs of holes drilled on each side to allow 1/2" bolts to drop through will allow any of the sides to catch the front of the bench.

Sand Bags

Sand bags are useful for blocking up a piece in progress. For small bags, sections of the legs from old blue-jeans can be sewn into sacks. Lumber yards sell sand in fifty-pound plastic fiber sacks that are sturdy enough to use as is if you need bigger bags. These are the same kind of bags used to make temporary flood walls. The same bags are usually sold empty as well, for about a dollar apiece, and are good for smaller sizes. The soft iron wire used for tying concrete reinforcing rods is the best thing for tying them closed.

A one dollar sandbag from the lumberyard.

Getting a Stone Onto a Box Truck

As long as you have a beam overhead, it's easy to load a heavy stone onto a flatbed or pickup truck--you just hoist the stone into the air, back the truck under it, and set it down. But how can you put a stone in box truck or a van without a fork lift or an engine hoist?

The trick is to build a temporary platform the height of truck bed. If the bed is low enough, you may even be able to use stacked up 4x4's or similar lumber. If it's a box truck, you'll probably need to knock together something out of 2x4's or 2x6's. Be sure it's strong--you'll have a live load on it, so be sure there is plenty of diagonal bracing. I have a heavy work bench made of 2x6's that's the right height, so I use that.

Hoist the stone a little higher than the platform, drag the platform under it, and lay some 2x6's across it to bridge to the truck. The gap will only be a foot or two, but be sure there's a generous length of lumber extending inside the truck for safety. Screw or nail the 2x6's to the platform and screw a piece of 2x4 across the 2x6's on side away from the truck so the stone can't accidently roll off the platform the wrong way. Finally, lay your roller pipes on the 2x6's and set the stone down on them.

Be sure to take it off the pipes once it's in the truck.

Dropping a Stone

Sometimes there is no good way to lift a heavy stone down from a truck bed. The obvious idea--pushing it off the back of the truck--is not out of the question if you pad the landing.

Ready to drop a one-ton block of marble. Note blocks protecting the van step and trailer hitch.

In quarries they bulldoze up piles of dirt or sand to catch huge blocks as they are split from the rock face. You can use a similar technique for stones of up to a ton or two in size. You can make a landing pad using several inches of flattened corrugated cardboard boxes, pool noodles, styrofoam packing material, a thick stack of moving blankets, cardboard boxes of dirt or sand, or any other crushable material that can absorb the impact. Soft ground, broken up with a shovel, if necesary, is fine too, but it may be hard to get the stone back onto a firm surface. I've even used old pallets blocked up at the ends to allow them room to flex and break.

No matter what you use, remember that this is for outdoors only! Don't do it on any interior floor unless it's a concrete slab laid directly on the ground, and beware that even then you could crack it.

Lay several inches of padding directly on the concrete with a piece of plywood on top to spread the weight and stop the stone from either pentrating through or scattering the padding to the side. If it's a very heavy stone you can use two layers of plywood with more padding between. The impact will break the plywood, but that's OK--the breaking soaks up some of the impact.

In the drop shown above, the block weights a ton, and there is about three or four inches of old gym mats, rubber floor mats, and a folded up moving blanket under the plywood.

You can use almost anything for the landing pad, but beware of bouncy padding such as tires. Padding that crushes is safer, both when you drop, and later when you take the stone off the padding.

You also need to plan how the stone is going to land so it doesn't fall backwards and bang up the truck. If it's a flat-bed you can just push it off, because there's an overhang. Vans, like the one shown here, may have a step or bumper that can be damaged if the stone doesn't clear it.

In the drop picture above, I've got a chunk of 12x12 timber and a triangular wedge of the same protecting the truck step. The blocks are arranged so that the moving stone will roll forward onto the triangular block, which will tip forward over the 12x12 block, which can only topple away from the truck and onto the pad. Needless to say, nobody will be anywhere near the landing zone when all this happens!

When you're ready to drop, put the block up on pipes, making sure that they are positioned so that the block can roll all the way off the truck. You can get a longer running start if you duct-tape the front-most pipe to the floor of the truck so it will be where you want it when the block hits it.

A one-ton block landed safely on the pad.

You can either push the stone off the truck (as we did here) or, if it's consistent with your landing arrnagement, you can tie the stone to something solid and drive the truck out from under it. Allow that rope may stretch a bit, so extend the padding a little farther under the truck. The stone can roll when it lands, or fling wood, pipes, or stone chips around, so everyone should way back.

In the drop pitctured above, we're just gave it a good push with a running start of a couple of feet. The blocks to the side were there to stop the block from falling over on landing. As you can see, the blocks both landed perfectly.

Beware that the stone will be unstable on the soft landing pad-those last three or four inches are more dangerous than the actual drop because you'll be up close to the unstable stone. Use the truck to drag the stone off the pad and onto lumber or plywood laid directly on the concrete.

Only drop stones that have a compact shape--long pieces and slabs can snap even if they are quite thick.


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