I have a number of different size holes up to 13 mm to drill in steel. I bought a set of jobber drills from Screwfix, but the 4mm one bent while drilling through chassis rail of a Catterham. I know one gets what one pays for, but there are Jobber ones, Titanium ones and Cobalt ones. What make/model of drills should I buy and from where for a reasonable price that will be servicable.