Cobalt Left Hand Drill Bit Set, 13Pcs M35 High Speed Steel Jobber Length Drill Bit Kit for Hardened Metal, Stainless Steel, Cast Iron, Wood and Plastic, with Index Storage Case, 1/16"-1/4"

For so long I went with just whatever came with the drill. These bits are so hard, and with a little bit of oil cuts super well and stays sharp. Left hand is extra handy to drill out broken/welded in screws. Love them. Would bring them to bed if I were allowed.

I used these bits to drill out a mild steel M4 bolt, then an M8 bolt. The M4 came out fine, then the M8 broke a bit because it had become so dull. I still have 1 more M8 to drill, but Imagine I will need to switch to a standard bit set to get started because of how dull these became.

I had a use case where a machine screw had broken off in a location that wasn't easy to access. I decided versus pulling the piece of equipment apart to improve access, I'd spend the money on a set of these with the hopes it would catch as I was drilling out the broken off screw. The screw broke during installation, so I wasn't worried about rust or anything like that, and the roll of the dice paid off. As I slowly increased the size of the bits, one finally caught and backed it out. I replaced the machine screw with a new one and job done. This set saved me about an hour of disassembly and for me, that made the set worth the price. I don't know long-term how they'll hold up, but for me, these will be used infrequently and as I mentioned, they've already paid for themselves, so future use is just money in the bank. The case is nice and the quality seems good, so no regrets here.

impressions following first, succesful, use. - bits are sharp and straight. - bits are capable of cutting deep into snapped stainless bolts without observable wear. tips: - the metal set case is tightly clipped together when closed and hard to open. instead of force, i've used a small pry tool. - drilling metal: i've started small, slow, then gradually ramped up speed and size - careful throughout. - reminder to drill "backwards" with left-hand bits. in the photo: the two bits that i've used to extract the snapped bolt, also shown.

cut well