In general, there is a trend away from percussion drilling and toward hammer drilling. Hammer drill bits are specialists for rough and tough materials, i.e concrete, clinker/brick, and natural stone. They come with hammer drill machines ('rotary hammer drills'), which transmit more impact energy than percussion drills and drill more effectively. For this purpose they have a special shank (up to 16 mm bore diameter, usually 'SDS Plus') that matches the hammer drill. Of course, hammer bits are also suitable for all kinds of stone, hollow stone, masonry, etc.. The hammer function is switched off during drilling as needed. Hammer drills can therefore completely replace percussion drills! As with all our tools, you get low prices due to the high order (purchasing) volumes. Please also refer to our tips on drilling for extra support.
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If drilling can be seen as primevally 'manly,' hammer drilling is even more so! The drill industry advertises martial figures who, like bikers, rely on their machines. The names of many products are a jungle of superlatives! But which drills are required for greening walls? Here, criteria are given that apply to diameters up to 16 mm and standard drill lengths.
P.S. It goes without saying-- but we'll say it anyway-- we are thrilled when women also buy our drills - and use them!
Yes, the number of cutting edges on a drill bit plays a big role, at least in drill advertisements which have the motto: "the more edges, the better." According to this logic, the classic 2-edge bit which looks like a percussion drill falls far behind the 3-edge bits and is thought of as inferior. But, it's not so simple! 2-edge drill bits still bore fastest! That's because the more edge surfaces a drill has, the slower it becomes. 3 edges use more energy, generate more friction and warmth, and become susceptible to overheating, thus wearing down faster. When the '3-edge bit' came, there were no obvious negative effects, but with the 4-edge- definitely! The professionals on the construction sites of tunnels, high-rises, etc.., which drill hundreds of holes every day, rejected the new drill quickly. Four crosswise-arranged cutting edges -- this was too much friction! The remainders of these first 4-edgers still float around today on the internet as "special deals" in various online shops...
The cross-shaped 4-edge bit is still popular, but it is not really 'genuine,' because two of the four cutting edges are wider and longer and they are the ones cutting and hammering, while the other two only support the drilling process as secondary/minor cutting edges and do very little on the borehole wall. Some suppliers even advertise more edges than are actually there-- somehow the bit's tip is considered and sold as a separate cutting edge... so even "five-edge bits" are actually only highly modified 2-edge bits!
...must be joined together, and this is usually done by soldering. The cutting body made of 'hard metal' (tungsten carbide...), usually in the form of a small platelet, is inserted into the prepared grooves of the drill shaft and surrounded there with liquid metal (brass or bronze solder). After cooling, the connection is then solid. The trend here was towards high-temperature restoration soldering at over 1,000 degrees. Such drills can withstand heating to several hundred degrees without the soldering becoming soft and the carbide plate loosening.
A new trend for very heavy hammer drills (over 5 kg) is mono-block cutting (solid carbide head): here a solid carbide body is butted to the drill shaft and thermally attached, e.g. with 'friction welding.' At the connection point, however, the two materials must match each another so that there is 'the right chemistry.' This means that the carbide body must not be quite as hard in this lower part that it loses its wear resistance at the lateral edges. Such hammer drills are more likely to wear out in the area of the lateral cutting edges (flutes) and may then drill inaccurately.
The shank of each hammer drill bit has a spiral helix called a 'flute' which lifts swarf (chips, filings, shavings, debris..) out of the borehole like an Archimedean screw. The geometric shape of the helix can be optimized with respect to width, depth and cross-section. The number of coils is also important. Normally, each cutting edge of the hammer drill bit also has one helix/flute; i.e double-edged has two flutes, 3-edged has 3 flutes, etc.. With four spirals, however, things can get tight, because these can no longer be milled so deeply into the shank...otherwise, not much remains of the shank and stability suffers. Spirals with too small a cross section cause problems with removing dust; the thrust of the drill falters and it can become hot.
Particularly with very long hammer bits, a 'core reinforcement/strengthening' of the shank helps with stability when drilling.
Which drill bits are available from FassadenGrün? Hammer drill bits are needed for drilling completely through walls, so then cables can be pulled through, or metal anchors placed that splay open deeper in the wall. Trellises on facades are usually mounted less deeply, not only to protect building materials, but also to avoid thermal bridges. Exact, circular rawl-plug (dowel) holes are needed for this! This may seem trivial, but is not self-evident and isn't so relevant with other drilling jobs. Wayward, oval holes will not distribute the expansion pressure of the anchor evenly in all directions, which can lead to weakened stability (in a mount) or even crack formations. The hammer drill bits offered by FassadenGrün have a centre point. This optimizes the drilling, reduces spalling of material as well as the 'waywardness' of the drill, and gives continued guidance in through the hole.
The number of cutting edges is also important: 2-edged and also supra-modern 4-edged bits mentioned in the window above, tend to knock sideways and 'break out' during drilling, while 3-edged bits steadily support themselves in three directions. The holes remain precise and don't become too big, the rawl plugs clamp well and do not 'twist.' Besides, 3-edged bits work with very little vibration, making it easier on the hands and arms.
The following therefore applies to climbing aids: "Less is more...three-edged bit instead of four!" Wherever anchors/rawl plugs are needed, you will find FassadenGrün's high quality 3-edged bit in ProfiPlus-quality-- individually or in cassette HB 44444. The 16 mm sizes are only available individually as HB 16210 and as an inexpensive short version- HB 16160. When bonding with composite mortar (as with some heavy construction), the precision and quality of the drilled holes is not as crucial. Here, two inexpensive 4-edged bits in professional quality have been recommended-- HB 16310 and HB 16450-- especially for long lengths (in some wall insulation).
All hammer drill bits from FassadenGrün also break reinforced concrete; so, you can drill through steel reinforcement without changing direction!