Things You'll Need
5 wooden beams, 4-by-4-by-48 inches
Drill bit, 1/2-inch diameter, 8-inches long
8 bolts, 1/2-by-10 inches
8, 1/2-inch washers
8, 1/2-inch nuts
4 chain and pulley systems
You can build a simple gantry crane that is portable. Small gantry cranes can be used on building sites to lift bags of concrete, pallets of lumber or any miscellaneous parts that are too big to lift by hand. Gantry cranes can also be used to lift engines, transmissions or other heavy parts used by mechanics. The beauty of the smaller gantry crane is that you can assemble it over the object, lift it and when you're done, disassemble the crane and put it away for future use.
Place one 4-by-4 post flat on the ground. Make a mark on the post 6 inches down from one corner. Place a straightedge from the opposite corner on the same end and draw a line down to the mark. This should be an approximately 60-degree angle.
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Cut down the line with a handsaw to form a spear-like point on the post. Draw and cut the other three posts exactly the same.
Lay two of the posts out flat in the shape of an A; the angles should be facing each other. Stand the remaining post up vertically between the angles. The angles should fit flat against the sides of the post. Place a hand clamp over the end of the A-shape and tighten just enough to hold the vertical post up.
Drill four holes through the top of the A-shape with a cordless drill and half-inch drill bit. Space them evenly so that they penetrate completely through the legs and the vertical post.
Lay the other two legs out the same way. Release the clamp on the vertical post. Flip it over and place it between the other two legs. Drill through the top of the A-shape again just as you did on the other set of legs.
Insert 10-inch bolts through each hole going all the way through both legs and the vertical post. Place half-inch washers and nuts on the other end of the bolts. Tighten them securely with a socket and ratchet.
Grab the vertical post with both hands. Tip if forward until it's horizontal. Stand one of the other legs up in place on the end. Insert one of the bolts through the matching holes. Stand the other leg up and slide it onto the end of the bolt. Insert the remaining three bolts through the holes. Put on the washers and nuts and tighten securely to secure the legs on the gantry crane.
Loop four chain and pulley systems evenly spaced along the top of the beam. Lift a load on a single chain and transfer the load to the next chain to move the load from side to side. Or you can use a single pulley system and slide the load.
For more versatility, you can bolt an I-beam to the bottom of the horizontal wooden beam. Install the pulley system on the I-beam on rollers or "trucks" and slide the load from side to side. This is more expensive and complicated and usually not required equipment on simple wooden gantry cranes. The height and width of the crane is an example. You can make it longer, shorter or taller.
If lifting extremely heavy weights over 500 pounds, add a horizontal brace between the legs of the A-frame if needed.