A concave surface is not normally recommended because there is the possibility that the tool turns away from the centre. Feed should be reduced to 1/3 of the recommended.

The surface of the tool to be drilled on should be preferably even. If the angles exceed 2°, feed should be reduced to 1/3 of the recommended.

If the starting surface is an uneven surface of the component, feed should be reduced so that the chip of the cutting edges can be avoided. The same can also happen at the way out from the tool .

When working with a hole made beforehand, this should not be bigger than 1/4 of the final size, because the tool could turn away.

There is the possibility to drill sets of more than one piece.

When the tool has a crossed hole, which is 1/4 bigger than the diameter of the drill, feed should be reduced when going through it.

The axis of the tool should not be deviated from the centre of the piece more than 0,03 mm. so that the pointed tolerances are acquired.

The tool should be assembled in a way that the face of the central insert goes parallel to the cross movement axis of the machine

When a drillholder with a housing supplier of cutting fluid is used, it has to have a fixed top so as to avoid that the housing turns round.
If it is the case that the cutting fluid has some dirty rests, this could lock the rotary housing and, consequently, the supplier tube will roll up around it, which can cause a serious accident.
If it is the case that the drillholder has not been used for a long time, check if it turns round in the housing before the spindle starts working.

When through holes are drilled a disk is produced after the drill has finished the hole. This disk is oftenly thrown away at high speed through the dish claws and can cause injuries and accidents.
In order to avoid this accident, a suitable safety system has to be placed around the dish.