WEILD A SIMPLE SCREW JACK

Image Gallery BELOW. Heavy-duty nuts and bolts come in various lengths and diameters, as this assortment shows. The center bolt has a curved top plate . . . for specialized uses. In the background, lengths of pipe are welded to base plates RIGHT. Here is a homemade telescoping screw jack-the versatile ""high rise"" model-on display.

For uplifting experiences..

By David E. Johnson

The-screw-jack one of the simplest and 'most basic machines ever invented is a willing workhorse `that' has helped people now and again . . around the homestead, in construction work, and in the field of maintenance. The weight-tracing device may cost anywhere from $10 to $24 (depending on its size) if, purchased from a department store or mat order house. But if you're adept at scavenging and have access to welding equipment and a heavy duty 4 drill (or oxyacetylene torch), you can make your own, using materials that are often found lying around in junk piles, free for the taking.

THE BASIC NUTS AND BOLT

The-screw-jack teas only one--moving part, ;which does all the work: a nut that travels up the threads of its bolt. The homemade 'jack is turned with a wrench and consists of -six parts: a bolt, a matching nut, a section of pipe, a cap plate,'` a base plate, and a top `plate (which can -be replaced -by a nut, if desired).

For most of my jacks, I use Schedule 40 2"pipe and 1/4"- to 1/2"-thick steel plate cut into 3" or 4" squares. When it comes to the nut and bolt, the idea is "the bigger, the sturdier", especially on heavy jobs such as ,house leveling. For my last model, I used a 6 "-long, 1 "-diameter bolt with 10 threads 'per inch. (EDITOR'S NOTE: In high-load situations, an acme-threaded bolt-generally used for power transmissions-would be the preferred choice . . . but you'd need to find a matching nut.] I found the pipe and steel plate in a scrap pile behind a local machine shop. You should be able to scrounge such material from similar places or else pur chase it inexpensively at a junkyard.

WELD IT TOGETHER

To begin, you'll need to cut your pipe to tie appropriate length for the job at hand. Nerd.,-weld;he. base plate onto the. bottom of this conduit (see the diagram). Now, cut (with-an-oxyacetylene torch) or drill a hole that's slightly larger than the diameter of the bolt's shaft- into the cap plate. -(If the pipe you're using is galvanized, be sure to dog -the" welding 3n a well-ventilated area.) Slip the bolt headfirst into the open end of the pipe (so that `the head can act as a brake if you try to turn your jack too far), slide the cap plate down over the threaded shaft, and weld it, to the pipe is e.All you need to do now-to twist on the moving nut and add a bearing surface to the-top, end of the bolt. Sometimes I attach a top plate, land at other times I merely tack 4n at! extra nut, flush with the top of the bolt. Once that's done, your screw jack & ready louse!