Comparison Jet JDP-8L vs Intertool DT-2130

The largest spindle overhang provided in the design of the machine.

The overhang is the distance from the centre of the spindle to the supporting column. The maximum overhang corresponds to the greatest distance from the edge of the workpiece to the centre of the planned hole, at which this hole can be drilled on this machine; if this distance is greater than the overhang, the workpiece will rest against the support column and the drill simply will not reach the right place.

Note that this parameter is relevant only for vertical and radial machines (moreover, in the first case, the overhang is generally unchanged; see "Type"). But magnetic models do not have a limit on the size of the workpiece, so the overhang is not indicated for them at all.

The greatest distance that the spindle (quill) can lower from its original position. Theoretically, this is the maximum drilling depth that the machine can theoretically provide; in fact, this moment also depends on the size of the drill and the characteristics of the material. In addition, we note that manufacturers usually choose the stroke of the quill taking into account the general class and purpose of the machine; so this moment is rarely critical when choosing.

The type of chuck — a clamp for installing drills and other working nozzles — used in the machine.

— Key. Chuck opened and closed with a special key. Also known as "gear" or "ring gear" because the wrench works like a gear. It is used to secure drills with a cylindrical shank; for this, the design has cams (usually three) that converge when closing and diverging to remove the drill. The cam clamp itself is quite versatile and is able to work with any drill or other attachment that has a round shank (regardless of its additional features). For example, even nozzles with a Weldon shank are sometimes put in such a cartridge (see below). Specifically, the key cartridge is considered somewhat more reliable than the quick-clamping one similar in principle; its main drawback lies directly in the use of the key, which can be lost. In addition, the replacement itself takes a lot of time.

— Quick release. A chuck for cylindrical shanks, the design of the clamp is completely similar to the key (see above). The main difference is that the keyless chuck is opened and closed by hand, without the use of any special tools. Due to this, changing drills takes much less time (hence the name), and in general, working with such a cartridge is easier than with a key one. It is considered the best choice for those cases where you need to change drills frequently. The disadvan...tage of keyless chucks is considered by some to be less reliable than key chucks; however, this may turn out to be critical only at very high loads, and for normal use, the capabilities of such a fastening are quite enough.

— Morse taper. Morse taper is a specific type of shank used in drills and other similar bits. Such a shank, in accordance with the name, has a conical shape — the socket in the cartridge is designed for it. At the end of the shank, there is most often a foot — a flat ledge, which, when installed, is fixed in the groove of the cartridge and does not allow the drill to turn. However, there are other options for retainers — for example, with a thread, when a special rod is screwed into the end of the cone during installation. In order to select compatible drills, it is imperative to know the design features of a particular Morse taper chuck. Also note that such fasteners are available in several standard sizes (see "Morse Taper").

— Weldon. The Weldon clamping system features a cylindrical shank with a flat, a small flat notch on one side. The chuck has a clamping screw, which, when tightened, rests against the flat and fixes the drill in the socket. A rather exotic type of fastening, which has not received much distribution in the post-Soviet space. This is partly due to the fact that the Weldon drill can be clamped in a regular shank chuck without much difficulty (although this is not particularly recommended, as it can lead to imbalance at high speeds). This type of chuck is mainly used in magnetic machines (see "Type") — and then most often in combination with another, more common type of fastening (for example, quick-clamping).

— collet. A cartridge that uses the same working principle as an automatic pencil. The role of the clamp is played by a round sleeve, divided into several springy petals; in the working position, they are compressed and fix the drill, and to open it, you need to pull the chuck casing up, and the petals will disperse. This way of working is not reliable enough for full-size drilling machines, but it is optimally suited for high-precision units using small diameter drills (up to 4 – 5 mm).

Note that several chucks can be supplied with a drilling machine at once, including those for different types of shanks (for example, Morse taper and key). The latter significantly expands the range of working nozzles available for the unit. At the same time, a specific combination of fasteners can be practically any — except that the key and keyless chuck are not supplied in one set, because. they are designed for the same type of shanks.

The size of the Morse taper chuck (see Chuck Type) that the drill is equipped with.

Morse tapers are available in several standard sizes. The most popular standard provides marking with the letters MK and a number — for example, MK2. The larger the number in the designation, the larger the diameter of the cone and, accordingly, the thicker the drills in which it is used. In modern drilling machines, chucks with sizes from MK1 to MK4 are usually used. But in fact, this parameter is necessary primarily for the selection of compatible drills.