Rotation speed
The speed of rotation of the working nozzle provided by the tool. Some models have a fixed rotation speed, others allow you to adjust it within a certain range (see "Number of speeds").
For different types of tools and types of work, different values of this parameter will be optimal; therefore, it is worth choosing taking into account the tasks that are planned to be solved using the tool (it is best to consult with special sources). We note only a couple of general patterns. So, for engraving on relatively soft and pliable materials (wood, glass, soft metals), high speed is not required, but for hard and difficult to process (steel, precious stones), a high-speed tool is better suited. But when drilling, note that for the same power consumption (see above), more revolutions, usually, means lower torque values. That is, here “high-speed” tools are better suited just for soft materials, and low-speed tools are better suited for hard and heavy materials.
Collet diameter
The diameter of the collet provided in the design of the rotary engraver (see "Device").
A collet is a specific type of fastening: a split sleeve, the “petals” of which can be compressed and unclenched by twisting / unscrewing the clamp. For a number of technical reasons, this mount is considered optimal for engravers. In order to properly install the working nozzle in such a tool, it is necessary that it fits the diameter of the collet (to be more precise, the mounting size of the nozzle should not exceed this diameter).
Note that there are several standard collet sizes. The most popular is 3.2 mm, but there are other options. And some engravers can be equipped with several mounts of different sizes.
Total number of nozzles
The total number of working attachments supplied with the tool.
The abundance of attachments allows the machine to be used with various materials and for various types of work. At the same time, this parameter significantly affects the cost. Therefore, when choosing, you need to proceed from how important a variety of possibilities is for you - so as not to overpay for extra nozzles that turned out to be useless in fact.
Note that this item is indicated only for engravers (see "Device") - for models of other types, specific types of nozzles are given in the corresponding item (see below).
Weight
The weight of the tool can be indicated according to different rules: some manufacturers take into account only the body without a nozzle, others — with a standard working nozzle, for multi-tools (see "Device") the weight of the main unit without a replaceable head, etc. can be indicated. These points are usually specified in the specifications or detailed documentation.
In the case of a power tool, weight has a dual meaning. On the one hand, the smaller it is, the easier it is to hold the unit in your hands during long work and the more convenient it is to carry out fine, accurate processing. On the other hand, a light tool is less stable and has an increased tendency to jerk, which is important under difficult conditions and hard materials.
