Today I was trying to drill out broken studs in an exhaust on a shogun. I was using a dormer hsco (combat) drill bit using cutting fluid and working my way up through the sizes in 0.5mm increments and was bluntening them like it was going out of fashion.

Anybody got a good suggestions for high quality drill bits for working with tempered, stainless and high tensile steel? I ask as £40 in drill bits to get 2 holes bored just doesn't seem feasible. Cheaper than a new cat but still.

I get mine from ukdrills.com

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Good drill bits are expensive. Drill at low speed and keep cooling the drill bit and stud, plus the cutting fluid as you have been doing, & wear safety glasses! Procrastination, mankind's greatest labour saving device!

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If you keep blunting them then sharpen them, any angle grinder with a grinding disc will do of you don't have a bench grinder, these days most drills work better when sharpened even new ones. my PC is slightly to the right of Genghis
2012 HSE SD4 In Orkney Grey now gone, best car ever.

I have a fairbucket full of blunt bits,, might invest in one of these and spend a rainy day sorting them
the drill doctor is allegedly the best but double the money

http://www.screwfix.com/p/titan-hss-drill-...230v/1566H

https://www.amazon.co.uk/Sealey-SMS2008-Drill-Sharpener-Mounting At work
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I Do have a devise for sharpening them in a bench grinder! Probably not as good as the drill doctor would be but it does work. The problem I was having was brand new out of the packaging or freshly sharpened they just wouldn't even scratch the material I was going into as it was that hard. Was wondering if anybody had a recommended type or manufacture of bit they prefer. I was using dormer bit always been led to believe they was a good make?

If the metal is that hard you only have one option, heat it to red heat and bury it in hot sand and allow to cool for a couple of days my PC is slightly to the right of Genghis
2012 HSE SD4 In Orkney Grey now gone, best car ever.

i went on a training course re drill sharpening, altering the rest height on bench grinder holding at correct angle. sometimes I do a wonderful job most times I make it worse.

My Dad still moans about wasting money sending me on the course 30 years ago everytime he picks a blunt bit , yet if I buy a new set he moans, 'you dont need them youve been on a course' At work
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You can get away with some pretty crude angles when sharpening drills, the big problems are the angle across the tip being nearer to 180deg rather than 90 or less and the cutting edge is lower than the trailing edge, providing the drill cuts away from the cutting edge it will drill. Generally it's pretty near when the swarfe comes off in nice spirals.  my PC is slightly to the right of Genghis
2012 HSE SD4 In Orkney Grey now gone, best car ever.

I recall "back in the day" for really hard jobs, instead of Dormer HSS bits we used "Cobalt" bits. They were quite short but "well 'ard".

Bob 10MY (Sept 09) TD4 HSE Auto in Stornoway Grey (Now Gone)

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It was a Cobalt bit clearly just the exhaust studs had been tempered over the past 10 years of use. Just wanted to know if any one had any bright ideas for future reference. Thanks for everyone's input.

Recently bought a 1/2 cobalt bit, cost an arm & 2 legs! https://www.bunnings.com.au/sutton-tools-2...t_p6350492 Procrastination, mankind's greatest labour saving device!

Acoustic insulation ARB TPMS 3xARB air compressors After cooler Air tank On-board OCD pressure air/water cleaning Additional 50L fuel Carpet in doors ABE 2x1kg Waeco 28L modified fridge Battery 4x26ah Solar 120w Victron MPPT 100/20 DC-DC 18amps 175amp jumper plug Awning 6x255/60R18

Wow! When I last used them, the Queen was paying for them!  10MY (Sept 09) TD4 HSE Auto in Stornoway Grey (Now Gone)

08 FL2 TD4 SE Manual in Rimini Red (Now Gone)