After spending three hours laying on my back drilling out the busted exhaust studs on my son in laws BMW M5 manifold and destroying five of those Dewalt drill bits I think its time to get a high quality set of bits that I can re-sharpen and reuse. Where and what brand is the very best? I want both numbered and lettered bits.
On another subject,,, If someone should ask you to help replace the clutch on a 2002 BMW M/5, Lock the door, Take the phone off the hook, and Run fast and hide.
Australian made Sutton are excellent, as are the English made P&N if you can find them. Sounds like the job is pretty tough, have you considered using tungsten carbide?
Standard tungsten carbide tipped masonary drills from any hardware shop can be sharpened properly to 118 degrees and removing the negative rake using a green silicon grinding wheel. This may be a cheap, inexpensive alternative. Keep the RPM's low and coolant as to not overheat and melt the silver solder that holds them together.
I have used these in toolrooms for years. Whilst the diameter drilled is inaccurate they are a cheap method of removing broken punches, studs, bolts, cap screws etc.
David, you just answered a question I've had regarding carbide tipped masonry drill bits. I've bought some very expensive carbide drill bits in the past and the sticker shock was a little hard to recover from. And on top of it all the carbide bits will not take any abuse at all. To me drill bits are like screwdrivers, they're perishable tooling. And of course drill bits are perishable but often they're more perishable thane at other times. .
Anything else is a waste of money. IMHO
Try mscdirect.com. More tools then you will ever want. We use mainly cobalt drills in our shop. They're good for materials ranging from plastic to Inconel.
I don't buy carbide drills because they break too easily and are pricey. We run low volumes so no need to invest. We do use insert drills though.
For tougher drilling, look for a split point cobalt drill bit with a 140 degree cutting edge. The flatter tip resists chipping the edges. This is what we used when drilling stainless steel and they held up well. For better control and working in tight places, I would also recommend going with a stub drill instead of the standard jobber length drill.
On a side note, I seldom drill out broken studs/screws. Instead, I weld a nut to what is left and the heat from welding usually breaks the stud/screw free. Adding heat to the manifold area doesn't hurt either.
I take masonry bits to my drill doctor and put a split point on them not expensive but great for rusted bolts!