wristpin
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Often have to work on lawnmowers where alloy cutting spindle housings are held to steel deck pressings by 3/8" "taptite" self tapping screws. Steel screw + alloy housings + years of corrosion sometimes results in a sheared screw which being designed to self tap into the housing is as hard as ****!
If they shear flush with the surface can sometimes can mig a nut onto the the bit left in the housing and helped by the heat from the migging wind it out but otherwise it is a matter of attempting to drill it out.
Are the so called Cobalt (coated?) drills likely to be any better than a quality HSS twist drill and are there any quality standards for them? Equally does anyone have any alternative suggestions (other than don't shear it in the first place!!!)
If they shear flush with the surface can sometimes can mig a nut onto the the bit left in the housing and helped by the heat from the migging wind it out but otherwise it is a matter of attempting to drill it out.
Are the so called Cobalt (coated?) drills likely to be any better than a quality HSS twist drill and are there any quality standards for them? Equally does anyone have any alternative suggestions (other than don't shear it in the first place!!!)