I must confess - I'd been whirring away at high speed and applying a lot of pressure - leading them to snap or make very little progress, I tend to use 3 in 1 oil or cheap engine oil in a dripper as a lubricant. I don't drill metal often, and throw any bits I think are crap immediately in the metal pile. I never considered a lack of technique - its obvious when its written down - I can even remember being told in school metalwork to go slow with metal on the pillar drills and use lubricants, I just simply never made the connection.
It's all been said: carbide drills, cutting fluid, can't go too slowly, plenty of pressure, start with a centre punch, then a small drill and increase size. Don't waste time sharpening small drills, just buy them in batches of 10. Step drills are the only way for sheet metals, otherwise you risk getting a triangular hole; a metal punch is even better up to 5mm.
One of the engineers where I worked about 40 years ago told me he set the pillar drill to 30rpm and always use a bit of oil for cooling - even a bit of spit is better than nothing. He also taught me to sharpen drill bits freehand on a grind wheel - so useful. I have to admit that the 3 stepped cobalt bits I have now are the best I've used. I think they're hard but quite brittle. Not to be used to enlarge a hole that's already there or it snaps the tip off - don't ask me how I know
As a B.S.A. apprentice we were made to practice sharpening twist drills with mild steel ones, made for that purpose. Made me smile in more recent years at JLR where time served mechanical engineering apprentices couldn't even sharpen a twist drill bit by hand. Tried a few few drill sharpening devices over the the years, not brilliant, long winded and slow, imo. As with everything else these days, there's a lot of junk out there.
I have a tin full of High Speed drill bits, that I have had for over 30 years. I got them from our engineering shop, at a printers I worked at. No make name on them, but they are the best drills ever. When I use them, I always drip oil on them to stop them getting too hot, and they never really go dull enough that I can’t sharpen them up just by touching them up on the bench grinder. You soon get used to the angle to bring them at…
I think it’s all down to the relativity of the material thickness x width of drill x speed. Always use a oil or cutting compound, for heat and cutting.
“How do you drill a hole, Swiss?” “Well Paul…Drilling a hole, is like making love to a beautiful woman. You go in slow, plenty of lubrication, to keep her cool, then slowly speed up when she starts to steam up. Add more lubrication, to keep it going in smoothly, then give it a final push, and come out of the bottom, then pull it out!”
complete rubbish sorry … Carbide drills are extremely brittle and used for drilling super hard materials eg a snapped of drill or tap .. the “ can’t go too slow and plenty of pressure “ isn’t correct there is an engineering formula to work out speed and feed rate ( 1000 x S /Pi xD ) .. The A002 drills are TiN coated ( gold coloured) biggest problem is battery drills generally run too fast
