Knives are intended mainly for stripping and stripping bare conductors on wires and cables during electrical work.

Fitting knives

Mass-produced knives are predominantly folding. They have locks that prevent arbitrary folding. Knife blades are made of tool steel, the rest of the metal parts are made of structural steel. Heat treatment gives the blade a hardness of HRCa = 50...55. This hardness is slightly less than the hardness of the file.

The difference between a fitter's knife and knives for other purposes is that the cheeks or the handle shell are made of non-conductive material. The safety requirement is aimed at protecting the life of the worker. The B-3 brand knife is shaped like an NM-2 knife, but it is not folding. The fitter's naval knife is single-blade, with a fixed screwdriver. Its butt is wavy, sharpened to strip the cable insulation. The knife handle is plastic. The length of the knife when folded is 113 mm.

Monter's three-piece knife - two-bladed. One of the blades has a wavy sharpened butt. The screwdriver is also "hidden" between the cheeks of the handle. Special fitter's knife brand NK - for removing insulation from the cable. It cuts, say, plastic insulation along a line parallel to the longitudinal axis of the cable. The depth of the insulation cut can be changed with a screw in the heel of the knife.

Knife brand "Electron" interesting design. It is supplied with a set of tools for the fitter-electrician. If the pliers are tightly attached to the handle, then gimlets, chisels and other tools, if necessary, are connected to the handle. The handle itself is given an elegant shape, and several division scales are applied on the cheeks. The disadvantage of the knife is in the electrically conductive handle made of aluminum. The owner of the knife should make the handle non-conductive.

Mounter's knives are rarely on sale. The craftsman will find a replacement for them. Knives for other purposes are adapted for fitters. A fragment of a table knife with a handle, for example, or a lancet is quite suitable for this purpose. What conditions must satisfy the fitter's knife?

1. Non-conductive handle (two or three layers of insulating tape will change the quality of the metal handle) longer than 100mm.

2. The straighter the blade, the easier it is to remove the wire or cable insulation.

3. A blade without notches and burrs, having a double-sided sharpening, forming an acute angle of 30 ... 40sh. The wires used during installation and repair in an apartment and an individual house consist of an insulation sheath and a metal core or metal cores.

Separating the insulation from the core without damaging the latter is not at all an easy task. There are a few things to keep in mind here.

1. The thickness of the core, determined by the number of square millimeters included in its cross section. The thinner the core or cores, the more difficult it is to remove the insulation. Henceforth, in order to avoid repetitions, I will only mention single-core wires.

2. When releasing the wire insulation somewhere between its ends, the knife should be moved away from itself, only touching the adjacent surface of the core. A common mistake is removing shavings from the strand. To make these chips smaller, firstly, the wire is straightened at the point of opening; secondly, the toe of the knife blade must always be ahead of the handle, and the more significant this advance, the less damage to the core; thirdly, the increase in the angle between the plane passing through the blade of the knife and the plane that absorbs the section of the core at a right angle to its axis, will also reduce the "mutilation" of the vein.

3. Removing insulation from the end of a wire with a cross section of more than 3 mm will become less laborious when you put a thumb pad on the end of the core, and hold the knife handle with your other fingers. The blade of the knife is carefully moved to the thumb, removing the insulation in the form of shavings with the blade if the insulation is stuck to the core. The fingers of the left hand at this time hold the wire.

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