How to choose a key with a ratchet: types and description of keys
What is a wrench, probably, everyone knows. But at the same time there are bad and good keys. What is the difference between them and how to choose a best ratcheting wrench sets and give up the bad, what can a good ratchet wrench do? Why buy a quality set if you rarely use it? Such an expensive set is better than a cheap counterpart, how expensive is it? These questions appear in people who want to buy this tool.
Main selection criteria There are a lot of shops that sell hand tools, they all have one thing in common: no, absolutely no useful information on the keys will be given to you! Therefore, you need to learn how to choose keys with the maximum chance for a successful result. First you need to think: what do we expect from any set of this tool? Here are some basic requirements:
maximum service life; transfer the torque to a nut or bolt as best you can; safety and usability; the most convenient access to hard-to-reach places.
Torque This is a physical vector quantity that determines the rotational effect on a solid body. The moment of force is determined by the formula:
M = Fxd, where: F - force acting on the body; d - lever of force.
That is, to have the greatest torque, the maximum length of the handle d, to which the maximum force F is applied, is directly dependent on the physical strength of the person. In order to transfer this torque to the maximum, the key must fit snugly to the nut, without deforming itself and not deforming the nut. For what the working surface should have the greatest possible contact with the nut and sufficient hardness of the surfaces that interact with the nut.
The deviation of the dimensions of the working surface is standardized, for cap-nut sets there is a special table of possible deviations. Each key in the set must be marked and correspond to the size of the heads of bolts and nuts. The instrument should have the following marking:
indication of steel grade; diameter of round spline nuts or shed size; trademark of the manufacturer.
As a rule, the surface is additionally treated with a special coating, which gives the product the best corrosion resistance and an attractive appearance.
Near each working part there must be a numerical size designation. The digit displays the size in millimeters between the inner edges of the hexagon for which a specific key is intended.
Two key key indicators: surface hardness and throat size - can be determined independently. To do this, a file and a caliper will be needed. You can determine the size with a caliper with an accuracy of 0.05 mm, and then you need to use a file to try to grind off a ring spanner ring. If it slips along the ratchet ring, then the steel is hard enough, if chips appear, then the steel is soft and unsuitable for the tool. Here the question is that the sellers will not allow you to sharpen a tool kit that has not yet been purchased.