amoolo 5/16" Cobalt Drill Bit(10pcs), M35 HSS Metal Drill Bit Set for Hard Metal, Stainless Steel, Cast Iron Box of 10

Proved ideal for drilling out a stripped Torx stainless steel screw, whilst cheaper that M42 cobalt bits.I've not cut hard metals before, so I did some research first, which proved essential:Stainless steel is very tough and generates massive heat when cutting. Red-hot temperatures can be achieved within seconds if cutting without regular applications of lubricant, so be cautious and keep your cuts small.Stainless Steel DO's:ALWAYS use lubricant - WD40 is fine.Apply HIGH pressure.Use LOW drill speed - If using a power drill pulse the drill to prevent high RPM.Allow the bit to COOL between cuts and apply fresh lubricant.STEP UP TO SIZE - drill incrementally larger diameters holes BEFORE drilling the desired diameter.Stainless Steel DON'Ts:DRY CUT - without lubricant, your bit will BURN within seconds of starting.Use HIGH RPM - excess heat will cause the bits cutting edge to deform.Use BLUNT bits - if you can't see 'wiring' from the cut, it's blunt.Cut TOO MUCH at once - you'll FLATTEN the bit heads.Use the WRONG bits - don't use masonry or wood bits to cut metal. It won't work.Most of these tips come from makeitfrommetal.com 'Pro Tips: How to Drill Stainless Steel'. I found Johnathon's guide extremely useful, and hope others will too.

I wasn't expecting too much at this price to be honest. I have now used them on a metal extender bracket attached to my motorbike side stand. I started with a small drill bit and then used the larger ones. The drill bits cut straight through the bracket and stand with no problem. I have no hesitation in recommending these drill bits.

Good quality.... lose them before they get blunt lol

item came as described came next day delivery

Strong

Returned and refunded. Terrible quality. Don't waste your money.

Excellent bit of kit, very easy to drill metal plate

Blunted when enlarging a 10 mm hole in mild steel. Had to resort to a hand file to get the job done.