This work is exclusively made with bits, which can be used as well on wood, in certain conditions. Several cases of works can appear :

• Drilling in thin surfaces
• Drilling in sheets of metals in several thicknesses
• Drilling in thick surfaces

The drawing

The method of quotation stays the same that for the wood, but given the hardness of the material, it comes along with the checking by means of a punch.

Begin by positioning the hole by means of crossed lines realized in the point to be drawn. Then, represent the place of the hole, by means of a blow of pointeau enough hardly so that the soul of the bit comes to find accommodation there without "going hunting" to be certain that the tip of the punch is between the lines, to tilt it to visualize the axis, then to raise it to strike.

During the plan, during several consecutive holes, always make at first the lines in the point to be drawn, in their exact quotation, before realizing holes in the punch.

The drilling: little and big holes

In the case of small diameter, until 6mm, the blow of punch is enough for assuring the centring. When the final hole is important, we begin by realizing a front hole in the axis of the blow of the punch, in the diameter 4 or 5 mm. It will be of use as guide to the definitive passage of the bit and the bigger diameter.

Handling of the drilling machine

The drilling of metals with a portable drilling machine does not give so good results as if this one rose on column drilling machine. Indeed, the drilling of metals demands three contradictory qualities: precision, delicacy and strength quite at the same time.

Start up the drilling machine in rather high speed, and accelerate to present the just bit at the level of the blow of punch. At this moment, the side handle has to serve only to maintain the machine, all the pressure must be assured by the palm of the hand, good in the axis of the drill. Penetrate into the metal until the quarter of the hole to be drilled, to loosen by accelerating the speed, to remove and break the shaving, put 2 or 3 gouts of oil in the hole, and take back the drilling up to the end.