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The carpentry work is greedy ankles, since it is necessary to assemble pieces of wood in an invisible and solid manner. Standard trunnions are sold in DIY superstores. But you can also make them yourself, in any section, length and diameter. This sector will allow you to value your hardwood scraps.

Text J. Jacquin - Photos B. Petit-Falaize

Practical advice

With this method, the shaping of the pegs presents less risk of accidents than the work on the lathe. But wearing goggles is still highly recommended.
● The round rods coming out of the die are "raw cut". They can be used in the state: the striations favor at the same time the holding of the assemblies and the retention of the glue.

The round dowels are intended to consolidate permanent assemblies of pieces of wood by interlocking, tenons and mortises or others. Arranged in T or L, the pieces are glued together and traversed by the ankle. For this purpose, a pre-drilling hole is drilled in both thicknesses.
● Made of hardwood (beech, usually) the trunnions of trade are grooved to ensure a better fit of the parts and enhance the effectiveness of bonding. The diameters most commonly used are 6, 8 and 10 mm, sometimes 12. The larger diameters are rather reserved for the frame, and are then cut directly on site as and when.
● Made in a flat iron chute (here 150 x 60 x 10 mm), this die returns to around € 1. It requires only a minimum of tools to allow you to make dowels to diameters of your choice, from 6 to 22 mm. And nothing prevents us from using the same principle for special fabrications of strong section (chair or ladder bars, for example) if you do not have a wood lathe.

The realization

In the direction of the length, draw with chalk or permanent felt a line on which you will point the centers of the holes corresponding to the diameters of the ankles.
● Drill with sharp drills, starting with a small diameter and increasing to the final diameter. Prefer a drill press, you will gain in comfort of use and quality of realization. The holes must be perfectly round, and the drilling axis well perpendicular to the surface of the metal part.
● To create the cutting lips, use a steel chisel-cutter. Hold the handle of the tool at an angle of approximately 20° and slightly at an angle. When striking with a hammer, start the metal at three locations on the periphery of each hole. The cuts are perpendicular to the point of tangency of the tool and the edge of each hole.

use

In a hardwood fall of about 40 cm, cut with a chisel or a hatchet with a section a few millimeters larger than the diameter of the future peg (square of 12 mm for a peg of ø 10, example).
● At this point, their regularity does not matter too much. Taper them slightly to squeeze one end into the drill chuck and engage the other side into the die hole. With the drill running at medium speed, apply downward pressure: the starting slab gradually turns into a round peg as the wood passes through the die.

draw

draw

If the die is held in a vice, take into account the thickness of the jaws for tracing. A useless precaution if you use the die tight flat between the trays of a workbench.

Mark holes

Mark holes

With a punch, mark the centers of the holes corresponding to the different diameters of the dowels. Space them enough to avoid overlaps when drilling.

Drill the thick metal

Drill the thick metal

In the absence of a real drill on a column, a support like this one is quite sufficient to pierce thick metal. Remember to lubricate the drill with a few drops of cutting oil.

Orient and save three cutting lips

Orient and save three cutting lips

Using the chisel, cut three cutting lips on the periphery of each hole. Pay attention to their orientation according to the direction of rotation of the drill. They must protrude by about a millimeter.

File

File

With a rat tail file, gently deburr the edges of the holes making sure to adjust the end of the lips exactly in alignment with the holes. The regularity of the ankles depends on it.

Discard falling wood

Discard falling wood

Ankles can be made from falling wood. Here, an oak floorboard is cut in the direction of the wood grain into squares with a cross section of about 12 mm.

Cut the ends into a point

Cut the ends into a point

Both ends of the stem are cut to a point. One is clamped in the chuck of the drill, the other is presented in the passage of the die corresponding to the chosen diameter.

Find the ideal rotation speed

Find the ideal rotation speed

A bit of trial and error is inevitable before finding the ideal rotational speed depending on the wood species. Push firmly, but not excessively so as not to burst the wood.


Video Instruction: Round Peg in a Square Hole - Numberphile