Passionate carpenter and expert in metal work, Roger Pacqueau has made a special support to make square holes.
Cost: about 60 € (recovery parts included, excluding cutting tools)
Time: 60 hours
Equipment: meter, caliper, fitter brackets, locksmith tools, bench drill, jigsaw, Ø 125 and 230 mm grinders, cut-off and grinding discs, drill, arc welding machine, metal lathe...
The mortise and tenon joints are regularly used in carpentry and cabinet making. Their machining is however long enough to achieve with hand tools. The ideal is to have a mortiser. This machine is used to machine square holes in a single operation, with a drill bit that starts the drilling while the chisel (hollow) gives it its final shape as it sinks into the room. With its engine placed at the top of a column surmounting a flat base, the mortiser looks a bit like a bench drill. But it costs more!
An ingenious design
To save money, Roger Pacqueau has adapted a drill of 1000 W. It is at an industrial scrapyard that our reader has found the majority of the other parts, in particular a set composed of profiles grooved in aluminum (Bosch ). Two sections form the base. They are joined by two symmetrical trapezoidal plates, carved in an aluminum plate. On the rear plate, a light (a hole) in an arc allows to tilt the column at 45°. This base welcomes the support Carpenter passionate and expert in metal work, Roger Pacqueau has manufactured a special support to make square holes. (fixed) carriage (mobile) used to move up and down the drill. The carriage consists of a plate and a perpendicular flange, bolted between two brackets. On the back of the plate are 2 ball boxes that slide on a vertical rail. Such a device also exists with a single 300 mm slide. Two side-mounted flat iron arms and connecting rods allow the truck to be maneuvered with a lever centered at the front. The set is braked downhill by 2 return springs (adjustable tension). Guided by a large pulley mounted at the head of the column, they are hung at the rear on the articulation of the lever and at the front on the top of the truck.
Machining of parts
All parts are machined or turned with a standard 3-jaw lathe. For precise bores (here on the drill stand), the use of a 4-jaw chuck or tray is recommended.
The blank of the chisel holder is pierced right through (Ø 19 mm), drill blocked, rotating the chuck of the lathe. The workpiece is then bored (Ø 44 mm).
Tightened between protected jaws, the chisel support is open transversely then on both sides in the length. Performed freehand (not the milling machine), the operation requires precision.
The pulley consists of 6 blanks flanged on each other by 4 CHC M8 screws then turned (Ø 140 mm). For the return spring, a groove is machined to the width (Ø 132 mm) and then chamfered. The pulley is then drilled (Ø 18 mm) at its center.
The steel shaft of the pulley (Ø 16 x 45 mm) is drilled (Ø 6.75 mm) at each end and M8 threaded. Once the two self-lubricated rings fitted on both sides of the pulley, the axis is threaded.
Assembly of the mortiser
Two return springs, guided by the pulley, are fixed at the top of the carriage and on the rear articulation of the lever. The moving assembly is placed in the up position to adjust the tension of the springs.
The threaded socket of the worm is welded under the body of the mortise vice. In flat iron (20 x 5 mm), it is extended by 2 guides (35 x 4 mm) sliding in the inner grooves of the base.
A drill vise can be mounted using an 8 mm plate bolted to the base.
Performed with the saw, two lights (12 x 70 mm) are created. They allow to direct the vice on one side or the other.