A detonator is used to trigger bombs, shaped charges and other forms of explosive device[?]. Detonators are often attached to a timer[?] to ensure that the explosion takes place at the desired time, or when the person laying the explosives has reached a safe distance from the blast. Detonators can be chemical, mechanical, or a combination. Many detonators' primary (sensitive to heat and shock) explosive is a material called tetryl.
... the other end of the axis pushes against the lower rim of the groove. While the axis is slipping around inside the groove, the friction between the axis and the groove ...