We dig a tunnel in search of a cave. The tunnel is fitted with crash barriers (B-profile, 80x120cm). The guardrails are 4-5mm thick and are made of galvanized steel. In order to avoid having to constantly change the drilling machine or the chuck when connecting the guard rail elements, we were...

Hi, ever used Punches instead of Plug and Feathers? Like this https://pixabay.com/photos/tool-centre-punch-metal-steel-2523806/ I used some with a very small drillling diamater (8mm) and it worked relatively good..... Advantages: very cheap (<1 Euro), small diameter. Disadvantages: less effect...