Giovanni Martignoni

Giovanni Martignoni (born May 3, 1830 in Lugano , † January 20, 1915 in Frankfurt am Main ), also known as Johann Martignoni, was the inventor of the twist drill .

In the first years of his life, Martignoni lived in Milan and Switzerland . In 1857 he came to Liestal in Switzerland and worked there as a mechanic and repairman in the Pölger silk factory. There he developed a welding and hardening process for metals, which he was able to sell to Morell and others in Aarau, among others .

He traveled to Bern and Zurich and saw a lathe in Reishauer's mechanics workshop with an eccentric drill that could be used to turn threads in nuts, which was an English development. With this idea he first developed a drill with straight grooves and tension springs.

Until then, drills had two grooves on the long sides that were directly opposite . The grooves were planed or filed into the drill, as there were no milling machines yet. Also on sticks came on later.

Twist drill, from Lueger 1904

In 1863 he lived in Düsseldorf , where he designed a drill with a spiral groove. It was much easier to drill and the holes were much more accurate than before. The coiled grooves also make the chips run off better. The grooves were filed into the drill in a spiral shape. Martignoni sold his drills to manufacturers in the Rhineland, Westphalia and many other places. The disadvantage was that the drills could not be ground or sharpened, so that after a while they could no longer be used. In addition, drilling machines had square clamping devices at that time, so that the drill bits were difficult to use. Because of its disadvantages, the invention was not recognized by many and was forgotten again.

In 1867 he lived in Wiesbaden and learned about twist drills from America that were being offered at the Paris World Exhibition. They now prevailed after there were matching chucks and emery wheels. Many now also remembered Martignoni's earlier invention.

He did not reap the reward of his invention; he had to earn his living as a mechanic well into old age because he did not get a pension. At the age of 80 he wrote down his life story.

Martignoni's further inventions are a milling machine and the disc turning tool .

source

• Albert Neuburger: Inventors and Inventions . Ullstein, Berlin 1921.