The upper half of your jack stand is very simple to assemble.
MOTHER EARTH NEWS STAFF
Every back-to-the-lander and suburban do-it-yourselfer needs at least one good jack stand in his or her workshop. Here's how to whip one up in two hours or less from scrap materials that can be found here and there.
Start with three pieces of 3/16-inch-by-2-inch-by-6-inch flat plate. Bend the last 1 1/2 inch on one end of each up 15 degrees, and grind out a curve on the other end so that the radius will fit the outside of a 1 1/2 inch pipe.
Then set a 12-inch-long piece of 1 1/2-inch pipe up on end with some 1-inch-thick spacer blocks around it. Equally space the three pieces of flat plate around its bottom and spot-weld them to the pipe.
Place the assembly on a level floor and, with a square, check all the way around the pipe to make sure that it is precisely vertical. Tap the legs with a hammer, as necessary, until the pipe stands straight.
You're now ready to cut three 11-inch-long pieces of 1/8-inch-by-1 1/2-inch-by-1 1/2-inch angle iron. Bevel the ends of the angles and position them so their tops fit snugly against the pipe and their bottoms are firmly spotted on the flat plates' "feet." Spot-weld the angles in place. Then double-check the position and fit of all components. When you're satisfied that everything is as true and fits together as perfectly as you can make it, weld all joints solidly. Go over each weld several times, if you have to, to make very strong joints.
Now center a 2-inch-long section of 3/16-inch-by-1 1/2-inch-by-4-inch channel iron on the end of a 12-inch-long piece of 1-1/4-inch pipe, and weld the channel in place.
Drill a set of 11/32-inch holes through the main assembly's vertical pipe near its top. Drill several sets of matching 11/32-inch holes in the 1 1/4-inch pipe. These holes should start near the welded-on channel and — with each set spaced about 2 inches from the last — run most of the way down the pipe. (Do not drill any holes near enough to the bottom end of this insert pipe to make your completed stand unsteady when raised to its tallest height under a heavy load.)
Put the bottom end of the 1 1/4-inch insert pipe down into the open top end of the main assembly's 1 1/2-inch pipe, line up any one set of holes in the first with the single set of holes in the second, and insert a 4-inch-long 5/16-inch bolt. It won't hurt to go ahead and put a nut on that bolt either to prevent the pin from falling out as the jack stand is carried around, and to act as a "safety" during the stand's actual use.
Paint your stand a bright color (so you'll be able to find it when you want it), and it's ready to go. Use a regular jack to raise whatever it is you want to hold up in the air, slide the stand under a sturdy crossmember of the truck, car, trailer, or whatever, lift the stand's insert pipe to the highest position that you can lock it in, let the load down on the stand, and your jack will be free for another job. That's what jack stands are all about!