How to make screw piles for a foundation or a fence with your own hands

Recommendation points

• Selection of rolled metal
• Calculation of pile parameters
• Barrel making
• Head
• Helical blade geometry

Making screw piles is a fairly simple process. The main thing is the presence of a small arsenal of cutting tools and a welding machine. The quality of the piles depends on the selected post material, shape, blade size and tip.

Long service life, high reliability, ease of installation, the ability to use on most types of soils have determined the high spread of screw piles in private housing construction. Every zealous owner can make screw piles with his own hands..

Selection of rolled metal

Many factors affect the quality and durability of piles. The main one is the quality of rolled metal of all pile components. In Russia, there are no clear rules, including a state standard, that would regulate all the characteristics of screw piles. For the manufacture of piles, steels with a low carbon content – up to 0.25% are perfect. When buying rolled metal products, ask the seller for a quality certificate and documents on passing technical control.

In the manufacture of piles, the following diameters are mainly used: 57, 76, 89, 108, 133 mm.

The screw pile structure consists of three parts:

• trunk;
• screw blade tip;
• head.

The pile design provides for two options for making the tip:

• welded – part of the pile shaft is used, which is narrowed into a cone;
• cast with a blade – welded onto the pile shaft.

A steel pipe is used as the pile shaft. These can be solid-drawn pipes or welded. Very often, a used pipe of the oil industry is used for homemade piles..

The bearing capacity of the pile is provided by a helical blade. The blade can be attached both to the tip itself and to the pile shaft. It doesn’t really matter. At home, it is very problematic to ensure an accurate calculation and a snug fit of the blade to the tip, therefore, basically, the blade is mounted on the pile shaft.

To reduce labor costs, you can use ready-made cast tips with helical blades, to which the pile shaft is welded. The use of a molded tip will ensure the correct entry of the auger turn, as well as the absence of the danger of blade breakage, guarantees high reliability of the product. In turn, the use of a ready-made tip increases the cost of the screw pile. For example, a cast tip for a 108th pipe in different manufacturers costs from 750 rubles apiece.

Calculation of pile parameters

The bearing capacity is calculated from several factors:

• blade diameter;
• the depth of the blade;
• type of soil;
• soil resistance.

The number of piles for a structure depends on:

• the weights of the structure, including partitions and roofing;
• operational load (weight of furniture and equipment);
• snow load in winter.

The number of piles must be calculated individually, based on the relief of the site, structural and operational features of the structure.

As mentioned above, almost all types of pipes can be used as a trunk. The main parameter will be the pipe wall thickness. For all piles, the wall thickness of the trunk should be at least 3.5–4 mm; with a thinner metal, the pile can simply break. And the greater the wall thickness, the longer the life of the pile. The increased wall thickness has a large margin of safety. The effect of corrosion on the bearing capacity of the column is also reduced.

Barrel making

A crown must be made from one end of the pipe. The length of the crown is 200–250 mm. It is necessary to cut 4–6 teeth, depending on the pipe diameter. The teeth are bent towards the center, obtaining a cone. The resulting cone must be carefully boiled along all the cuts..

On the reverse side of the pipe, at a distance of 70–100 mm from the edge, two holes must be made. They are used to attach a mounting device when screwing in a pile. The hole diameter depends on the pipe diameter. For pipes of small diameters, holes are not drilled, but small lugs are welded into which the levers are inserted when the pile is screwed in.

If, when making a pile with your own hands, you use a cast tip with a blade, you just need to put it on a pipe of the appropriate diameter and weld around the entire circumference, having received a finished end.

Head

For the manufacture of the pile head, a plate in the form of a square 250×250 mm is required. The thickness of the metal is 5–7 mm, if you use a thinner plate, there is a possibility of deformation. It is necessary to provide technological holes in the plate for fastening the upper strapping.

On one side of the plate, it is necessary to weld a small piece of pipe 100-200 mm long, the inner diameter of which is 1-2 mm larger than the outer diameter of the pile. Additionally, the plate is welded with small jibs to the pipe section. The head is mounted already on the screwed-in pile after cutting or building up to the required level of the pile trunk.

If the pile strapping is carried out with a profiled pipe or I-beam, then the head can not be used.

Helical blade geometry

When making piles with your own hands, the main problem that you will face will be the geometry of the blade. Sharp bends, uneven spiral lift, unsuccessful entry of the blade turn and incorrectly selected turn pitch can “bury” your pile at the initial stage of screwing.

The pile blade width depends on the trunk diameter. The barrel with a diameter of 56 mm has a blade diameter of 86 mm, for the 108th pipe – 300 mm. The thickness of the metal sheet for making the blade is 5–7 mm. It is better to cut the inner diameter of the blade with a plasma cutter, this will provide an even cutting edge.

After receiving the circle of the blade, it must be stretched into the screw. The blade pitch is 40–70 mm. The larger the step, the more difficult it is for the pile to enter the ground..

One of the easiest ways to stretch a blade is to tighten one end of the blade in a vise and hit the other end with a hammer to shape it. It should be remembered that with this method there is a strong vibration of the material..

We suggest that you familiarize yourself with the video, which clearly shows the method of making a screw pile with your own hands.