Impact drill and hammer drill

Impact drill and hammer drill: impact

Hang up a picture, run the antenna cable through the wall or connect two pieces of wood with the help of dowels: Drill holes accompany us in almost every home improvement area and in everyday life. In the past, a lot of physical strength was needed to laboriously fight through the material with the veil, today boring machines take the work off us. They achieve a significantly higher number of revolutions and thus more precision in drilling work.

With high speed, drills cut effortlessly into soft materials, like wood or plastic. But what if the material is so hard that the drill bits can no longer penetrate the surface - so if only one blow can crumble the hard material?

Than it will be a percussion drill or a hammer drill needed. Why there are different devices with different functions is explained here.

From the drill to the hammer drill?

Other than perhaps accepted are impact drills or rotary hammers no direct developments of the drilling machine. As early as 1860, the first pneumatic hammers were used in mining, but it was not until 1895 that the first electric hand drill was built. The (further) development is mainly based on the possibility to implement the drive units and impact or hammer functions in a handy format. This was implemented in 1953 with the impact drill and much later in 1914 with the first hand hammer drill. The combination of the drill with a beating function is thus more of a requirement than a further development and enrichment of the drill. Not without reason, there are still clean drills today.

The right choice of drilling tool

The meaning of these three drilling tools is the same - they are drilling holes. However, they achieve this through very different functions and with different advantages and disadvantages. Although drills generally rotate with drills, the cutting edges of the drills do not always intersect. This is already apparent when looking at the drills: wood and metal drills are sharp-edged and require specially ground blades that lift chips like knives from the material. Stone and concrete drills, on the other hand, are dull and crumble the surface by blows.

Impact drill and hammer drill: impact

Drill with round shank, SDS-Quick and SDS-Plus

The use of the drill results already from the name, However, this can also be misleading: If the decision in the case of glass, wood or metal drills is still simple and hardly guilty, the term rock drill can already lead to the wrong assessment. Although a masonry drill (depending on quality) is capable of drilling natural stones as well as bricks, the drill shank decides whether the right machine can be used. The first decision should therefore be the optimal machine and then the drill used.

Soft materials, such as wood and plastic, only need a rotary motion, which makes a simple drill sufficient. Bricks and light concrete walls require additional a beating function that should not cut the solid material, but smash it. In addition to the energy of the percussion drill but this much physical strength is needed, which transmits the impact function on the bricks. The physical power has its limits and quickly reaches its limits with harder material, such as concrete or natural stone. The hammer drill automatically generates the impact function and is therefore suitable for hard concrete and natural stone.

drillingoptimal materialpossible material
drilling machine- Plastic, wood, glass, aerated concrete, tiles- light brick, lightweight concrete
impact drill- Bricks, poroton, lightweight concrete- lean concrete (usable without impact function like a drill)
Rotary Hammer- bricks, concrete, heavy concrete, natural stone- softer materials with limited drilling quality requirements

What distinguishes a drill?

Drills have a relatively simple construction, but also brings a special advantage with it: Since the drill rotates only about its own axis and requires no additional axial movement, the drive axle can be stored quite easily precisely and with little play. Drilling machines deliver the best concentricity, depending on their quality. However, many manufacturers use the possibility of integrating a hammer mechanism, which indeed extends the working range of the drilling machine, but sometimes at the expense of concentricity. Real drills without impact function are only occasionally found in the professional field.

In addition to being used as a hand machine, almost all drills behind the chuck provide a neck so that drills can be used in a drill stand. The drill with cylindrical shank is for this purpose in a Sprocket or quick-release chuck tense and delivers very accurate drilling results. A drilling or impact drill should therefore not be missing in any household.

How does a hammer drill work?

Impact drills are externally hardly distinguishable from drills and by the simple integration of a striking mechanism, they occupy the main component in the drilling machine world. In addition to the usual functions, such as clockwise and anti-clockwise rotation or the speed control, they have the switchable impact function.

Impact drill and hammer drill: impact

Impact drill with keyless chuck

For the mechanical implementation of the impact function, the drive shaft is interrupted and arranged offset by means of gears. The motor and chuck are thus no longer continuously on one axis. The now shortened shaft behind the drill chuck, which additionally has to be able to move in working direction makes it difficult to have a simple yet perfect concentric bearing. The interruption of the drive shaft, however, allows the integration of the impact function. For this purpose, behind the short drill chuck shaft is a fixed sprocket in the drill housing. The chuck shaft also receives a sprocket - when pressure is exerted on the chuck, both sprockets slip over each other, resulting in the shock and the screaming noise known at high speeds.

However, the impact energy is dependent on the pressure exerted on the percussion drill. Without the required contact pressure If a hammer drill works like a drill without a hammer and with a deactivated impact function, it can also be used as such. It also has a sprocket or quick-release drill and is able to take the same drill.

Impact drills do not hit without contact pressure.

As mentioned at the beginning, Stone drills have no sharp cutting edges capable of removing chips from the material, such as a wood boring works. Bricks and lightweight concrete are too hard for a cutting process. Rather, the material is abraded by the rotary motion of the drill and smashed by the impact function superficially. The stronger the blow, the more material is broken off and greater is the work progress.

The impact function is implemented by two toothed discs with a saw toothing. If these are pressed together, they lift off from each other at the tooth tips of the toothing and strike each other again in the dental cavity. This video illustrates very well:

Video on the functioning of percussion drill and hammer drill

A hammer drill works without sweat and effort

In a cylinder filled with air is a Schlaggewicht, which is set by means of a motor in motion. The implementation of the drive can be done in different ways, but fulfills the same purpose. The impact weight is thrown forward in the direction of the firing pin and strikes the firing pin, which passes the energy to the drill. The compressed air behind the impact weight ensures that the weight moves back to the drive and again through this and the air compression to the front of the firing pin. With each movement, the impact is amplified by the air compression and does not require any pressure of the user.

Impact drill and hammer drill: drill

Heavy hammer drill in use at the construction site

The electric drive and the use of air compression characterizes this hammer drill as one electro-pneumatic hammer drill. Often, a pneumatic hammer drill is assumed to be a pneumatic hammer, but in most cases an electro-pneumatic hammer drill is meant. Pneumatic rotary hammers are referred to as pneumatic rotary hammers and are rarely used in the private sector.

Another variant is electro-mechanical rotary hammers, which work similar to the function of an internal combustion engine with connecting rod and cylinder. The movement of the connecting rod converts the rotary motion of the motor into a straight-line motion, with the "cylinder" striking the firing pin. Without the sweep of the flyweight and air compression in an electro-pneumatic hammer drill, electromechanical rotary hammers are less effective and are being used less and less frequently.

Unlike in a percussion drill does not move the drill spindle in the drilling direction, but only the firing pin and thus the drill with a rotary hammer. This assumes that the drill is mounted axially movable, which excludes a sprocket or quick chuck, in which the drill is firmly clamped. An SDS drill chuck is used here.

SDS chuck for holding drills with room for maneuver

So that the drill can move axially in the chuck and take over the impact energy, he must be stored with a certain play. This does not guarantee a quick-action chuck and the mechanics would not be up to the hard blows. SDS drill chucks are therefore used. Other types of tensioning systems, such as hexagonal shank or Hilti-TE, were also used at times, but were unable to assert themselves due to wear problems. The SDS system developed by Bosch - short for "plug-in rotary seat" - is now patent-free and is used by all manufacturers, which means that drills with SDS shanks are used in almost every hammer drill. Almost as there are different sizes that match the drilling capacity.

  • The smallest variant forms the still right new one SDS-Quick chuck, which is currently only used in Bosch cordless rotary hammers. The advantage of the small drill chuck lies in the possibility of additionally taking up long bit shafts. This can also be done with a handy cordless hammer drill.
  • This is common SDS Plus drill chuck, which is referred to as SDS feed due to its frequent use. With a shank diameter of 10 mm, it is predestined for all common drilling tasks in the private sector and covers all requirements.
  • Large drilling and stemming tasks require a larger drill bit holder, for which the SDS-Max lining is designed. The shaft diameter of 18 mm makes it possible to transfer the required impact force for very large drills and core bits and is often used in commercial areas.

Drilling hammer lift without rotary motion

Impact drill and hammer drill: chuck

Drilling and stemming hammer with SDS-Plus and SDS-Max chuck

Unlike a percussion drill, the hammer does not require rotational movement of the drill spindle to produce the impact energy. This function makes it possible to use the hammer drill as a chisel or chisel hammer. With deactivated rotation, the hammer works on the tool (chisel) and can be used for caulking in concrete and stone. It is advantageous here if the drilling and stemming hammer has a spindle lock which holds the bit in a predetermined position and this can not rotate. If the bit can still be rotated without a spindle lock, it is very difficult to caulk tiles with a large flat chisel.

Important in Stemmaufgaben is the specified impact strength of the hammer, While low impact energy can be compensated with some endurance while drilling, significantly more force is needed to clamp. Good combi tools for drilling and small stemming tasks are sufficiently dimensioned with a impact strength of 2 to 3 joules and are absolutely sufficient for home improvement tasks. However, for larger caulking and demolition work, a larger stamper with 5 or more joules or a large demolition hammer (up to over 20 joules) should be used. However, these devices operate in higher price regions and it is often appropriate to borrow the required equipment.

Not every hammer drill can replace a percussion drill or drill

The big difference between a hammer drill and a hammer drill lies on the one hand in the implementation of the impact function and on the other in the chuck. Rotary hammers can generally be recognized by the use of an SDS chuck. In this, however, only drills with SDS shank and no round shank drills (wood and metal drills) can be included. Although occasionally wood and metal drills with SDS shank are available, due to their function, however, they have a certain amount of play, which does not allow good concentricity properties. For isolated holes still useful, but they can not replace round shank drill in its accuracy.

Impact drill and hammer drill: chuck

Rotary hammer with exchangeable chuck for round shank and SDS-Plus

An alternative use offer attachable keyless chuck with SDS shaft. All round shank bits can continue to be used with a chuck. However, this variant has two disadvantages: Although quick chucks clamp round drill bits safely and with good concentricity properties, in this case they themselves use the SDS chuck with the existing play and can not compensate for this. The use of round shank drills thus does not improve concentricity. Another disadvantage arises from the included mechanism that is not suitable for a hammer drill. If you forget to disable the hammer function when using a plug-in chuck, the chuck can cause irreparable damage.

If the hammer drill is to be used as an all-round drilling machine, pay attention to an exchangeable chuck. This is not plugged into the SDS lining, but replaced with it. Thus, the rotary hammer with exchangeable chuck has the same concentricity properties as a drill. Comfortable and safe is the automatic deactivation of the hammer function, which excludes unintentional use. Rotary hammers with interchangeable chucks are sometimes a little more expensive, but true all-rounder.

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Video Board: Drill vs Impact Driver vs Hammer Drill