FAMAG | News from October 21, 2014

FAMAG Counterbore

If construction timbers to be connected together, there are various possibilities. A traditional and popular connection type is bolted connections using threaded rods or screws, washer and nuts.

On this, there are standards that prescribe to the thread used the dimension of the disc.

If the rule says it or it should be an optically invisible connection, the washer and the nut must be sunk into the wood. In practice, the carpenter drills according to the used thread with an auger bit a through hole in a wooden beam. In general, it is soft wood or wood construction. For sinking the washer/nut the carpenter uses a counterbore. Counterbore belong to the cylinder head drills and differ from the classical Forstner Bit and Cylinder Boring bit in the way that they do not have a centre point. Instead of the center point, have this wood drills a mounting hole into which a pilot drill or a guide pin can be inserted.

We offer 19 different diameters of the counterbore as Standard. Smallest diameter is 20,0 mm and the largest diameter is 120 mm. Counterbore in Ø 20 – 40 mm have a 8 mm bore, larger counterbore a 10 mm bore. Suitable for this two mounting holes we offer for each guide pins from 8 – 22 mm. By the way, we always finished the FAMAG-guide pins „under measurement“. Therewith is a very easy and precise guidance is given and there is no strong friction in the pre-drilled hole.

The mounted guide pins gives the counterbore a perfect guide and so also freehand drilling is possible in larger diameters than having a drill with a fixed centre point „in the usual dimension”. Alternatively to the guide pins are also pre-drills in diameter 8, 10 or 12 mm available. With a screwed pre-drill is drilling and countersinking in one operation possible and saves the time of the separate predrilling. With this combination tool is also an inclined boring possible.

Is it task to install several sinking’s at the same depth, we offer as a supplement a depth stop. This depth stop is made of aluminium and has a high-quality ball bearing and is thus rotatably mounted. It is for the FAMAG-counterbore (Ø 40 – 90 mm) suitable with a stalk diameter of 20 mm. The stop is powder coated and has a small depth. It is fastened with a clamping screw in the desired countersink depth on the stalk of the counterbore.

Often it is desired that sinking’s are made invisible and the bore hole is closed again after lowering and screwing. For this we provide the FAMAG Plug Cutter series 1616. These are perfectly adapted to the tolerances on the holes of the counterbore. Thus you need when installing the wood plugs neither a thick hammer nor cartouche putty. Quality Made by FAMAG in Germany!

By the way, there are up to diameter 50 mm a great alternative: The Pilot guided Bormax. Also here a receiving bore is mounted in the drill head of the cylinder head drill. However the diameter 4,0 mm.
You can decide if you insert the classic center point or a 4,0 mm pilot drill, both are included. A depth stop (Item No. 1621) is also available.