DELTA-F

In history we meet three different types of auger bits, which differ in the type of the spiral.

In the catalogue of company Weiss and Son dating from 1909, a drill bit is named “Lewis bit“. It has only one spiral with completely free centre and only one main cutting edge. Patents date back to 1809.

In 1855 another type applied for patent, which is known as “Douglas“ in Germany. This is an auger bit, which was produced through twisting a flat bar steel. It has a double-start spiral, two taper taps and two main cutting edges.

In 1884 Charles Irwin receives a patent for his auger bit and creates the third model. This drill bit has a round middle shaft with circumferential spiral. It is striking, that this spiral only started from one main cutting edge. The spiral of the second main cutting edge ended after a half turn. This trick made it possible to create a very large chip space, which enabled a very good removal of the chips.

In former times these auger bits were either produced with a centre point or a crest of thread.

For boring especially deep holes in wood, the use of auger bits is indispensable. The specialty of the auger bit is the large and coiled chip space, through which the wood chips are removed in direction to the shank of the drill bit. Today the power drills or cordless drills are working with a remarkable higher speed than 20 years ago. This means a higher load of the tools. Thanks to our innovative production, we were able to meet this challenge in a positive way.

Today mainly carpenters are using the auger bits “Lewis“ pattern. But they are also used for modern woodworking machines, like joinery machines. For freehand use the craftsmen really prefer a drill bit with a crest of thread. With this type of production it is possible to push the crest of thread into the wood and with the help of the drilling feed the auger bit automatically pulls itself with every turn into the wood. And the craftsman is able to concentrate on the drilling direction. In order to reduce the friction force of the auger bits - the tools might be quite long sometimes - we reduce the outer diameter of the tool. This means, that the diameter of the spiral becomes smaller than the diameter of the head of the tool.

Therefore it is not necessary to apply advance force on our auger bits, like e.g. when you are using drill bits with a centre point. And it makes work clearly easier, especially for larger drilling diameters or a larger number of holes to be drilled. We at FAMAG appreciate very much this kind of tip and therefore our Lewis auger bits are only produced with a crest of thread.

The FAMAG Lewis auger bits are characterised by a milled, round spiral. This type of spiral guarantees a highest bending stiffness with largest possible chip space. Herewith our auger bits transport the removed chips particularly good out of the deepness of the drilled hole and remain in very directional stability. This is especially important, when deep holes have to be drilled and the wood fibres of the material are trying to give the drill bit a direction of its own while boring.

Our auger bits are fitted with a taper tap, one main cutting edge and a crest of thread, which works very well in soft wood, but also in European hard wood. In order to minimize frictional forces on the outer surface of the auger bit, the diameter of the spiral part is slightly reduced towards the tool head during production. The result is a smaller diameter in the spiral area of the drills. In practice this reduces the contact surfaces in the borehole and makes work much easier. To protect the shanks from twisting in the drill chuck, they are manufactured hexagonal (from Ø 10 mm).

In our range we have six standard lengths (overall length) available from stock: 235 mm, 320 mm, 460 mm, 650 mm and 1.000 mm. Even longer drill bits we manufacture as special article, either cost-efficient with a longer shank or with extra long spirals. Overall lengths of 2.500 mm are the maximum which is possible and they are not uncommon. All auger bits are produced from a diameter of 5 mm up to 50 mm as standard (the overall all length of 1.000 mm only from Ø 14 mm). For quite some time we also produce additionally the overall length of 1.080 mm. These auger bits have a spiral of 1.010 mm and differ from the auger bits with 1.000 mm overall length, which do only have a spiral length of 380 mm resp. 535 mm (from Ø 34 mm). The advantage of the very long spiral is: Our auger bits transport the removed chips even more comfortable out of the deepness of the drilled hole and they remain in very directional stability.

The largest diameter we can manufacture on special demand in our production plant is 80 mm. More than 130 individual diameters in overall lengths of 235, 320, 460, 650, 1.000 and 1.080 mm are available.

Thanks to the universal drilling characteristics and modern production techniques, we mainly find only milled Lewis auger bits on the market today. They work much like Forstner bits: In the first step the taper tap pre-cuts the wood fibres of the outer ring of the boring. Immediately after this the main cutting edge comes and does the actual work of chip removal. FAMAG Lewis auger bits are used by carpenters, on automatic joinery machines and wherever deep holes need to be drilled.

In more than 150 years we have gained a lot of experience with regard to the interaction of chip space, depth of chip flute and the stability of an auger bit. Here, a few millimeters often decide on the success or failure of a deep hole drilling. There are clear differences, if you want to treat a soft wood or an exotic hard wood. Millions of FAMAG auger bits were produced and are in daily use. Carpenters and other professionals often tell us about applications, where only FAMAG auger bits are successful. This makes us a little bit proud. Due to these unique selling features the FAMAG Lewis auger bits belong to the DELTA-F family of FAMAG.

 

• perfect chip transport even for deep hole drilling due to the single cutting edge spiral geometry
• directional stability during deep hole drilling due to round spiral grooves
• nearly independent drilling as the auger bit pulls itself with its crest of thread into the soft wood
• clean hole entry due to separate taper taps
• low friction due to cross-sectional reduced tool head
• the hexagonal shank avoids turning in the drill chuck
• well suited for joinery machines due to the hexagonal shank with 60 mm length
• long service life because it is very easy to regrind

Overview of the most important details:

Beside more than 130 individual sizes (in the different working lengths) we also offer sets including the most common diameters. One version with 8 pcs (Ø 6, 8, 10, 12, 14, 16, 18 and 20 mm) with overall length 235 mm and four sets of each 6 pcs (Ø 10, 12, 14, 16, 18 and 20) with overall lengths 235, 320, 460 and 650 mm. Furthermore we have two sets with lengths of 320 and 460 mm, which contain additionally the Ø 22 and 24 mm.

 

In order to offer the possibility of drilling and countersinking in one working operation, we have suitable countersinks with different diameters for our Lewis auger bits in our product range. These countersinks do all have a 13 mm boring and can be mounted perfectly on the shanks of the auger bits. They are fixed by means of a clamping screw.

 

 

For the use on joinery machines we offer a special boarding auger bit for frame wood of our product line 1420.

 

 

For the treatment of very hard woods we are producing a separate product line with an especially coarse centre point and a bottom blade instead of the taper tap. Further information you will find in product line 1493.

 

 

All FAMAG auger bits with overall lengths of 320, 460 and 650 mm fit perfectly into the different FAMAG drill rigs. Depending on the version, they are adjustable in the setting angle and give a perfect setting of the drill from 45-90° angle.