I have the most useless set of drill bits on the planet. Excluding masonry drills, I use my bits mostly for sheet metal, body work stuff, and if they work on metal then I'll use them on wood too. But they are all blunt and I've got dozens. Attempts to sharpen them on a bench grinder have met with little success. I also have a gimmicky thing which is supposed to attach to a hand drill, but I've never got it working. So I keep buying more drills, expensive ones too, and quickly wear them out. So you professional engineers out there, what do I get for amateur use? Also how do I work out how fast to drill. I have a bench mounted pillar drill, a corded hand drill and a battery powered hand drill. YouTube videos give some clues but I'm still puzzled.
I would like to know the answer to this too as mine never last long either and for some reason I don’t throw away the blunt ones so end up trying many until I get a useful bit
You're not alone. I've got quite an impressive collection of blunt drill bits. I've found the cobalt bits from Screwfix tend to last longest. The drill sharpening attachments (I've got a Bosch thing) tend to be fairly useless. A proper sharpener/jig that does the right angles is a pretty complicated affair, usually found in machine shops.
I have a great set but the make is not on them. I've had them for 10+ years. They might be cobalt drill bits. They were about £40 for the set 0.5mm to 10mm in 0.5mm steps so not expensive per drill really, average £2 per drill. Too fast/not enough pressure blunts drills. The bigger the drill the slower the speed and the more pressure you need. In practice I find it difficult to go too slow with a hand drill. Dip the ends in lubricant, don't let them get hot. It's all in the action TBH. Common sense - they must cut not spin around polishing off the cutting edge, big ones need a pilot hole etc. If the spin without cutting you're going too fast or not applying enough pressure or a combination of the two. If I break mine I don't replace with anything very special, but I never buy boxes of jobber drills that work out at tuppence each, they are definitely crappola.
I like others are in the same boat as you , i watch the likes of cutting edge engineering in youtube drill massive three inch plus holes ,yet i cannot get an eighth inch drill make more than two holes then its knackered, i tried sharpening drills with the usual no success. Its a dark art. I think my drills are made of lead
I remember seeing 2" twist drills used where I worked as a young 'un tand they used a feed , constant stream of coolant and the drill was really slow. There's a formula for it somewhere. But there are drill bits and drill bits. I acquired a 1/2" bit from a factory 40 years ago that was still going until some idiot I foolishly lent to to snapped it a couple of years ago, I'd never sharpened it.
Hack saws are the same - got to let them cut. Slow/high pressure is the key. Fast and weedy polishes the cutting points off the teeth.
I think Kurtis does have some fancy piece of kit to sharpen them. Possibly showed it in one of his vids. Could also be prodigious use of the word "f---" that keeps them sharp
When I was a metal window and door fitter we had a drill sharpening machine in the so-called workshop but nobody used it because we were lazy and had accounts at the builders merchants. No idea if it worked.
I think that I have done best by buying packs of 10 same sized drill bits sold as cobalt jobber drill bits made by e.g. Dormer or Rennie cost a few pounds each in e.g. 4mm size. So over £20 a set.. A set of these last for ages, dont go blunt on cutting steel and have no trouble cutting stainless steel running slow with high pressure.
We use Dormer A002 HSS TiN coated drills , can cut stainless all day long if speeds are correct , and cutting oil ( Rocol) . If bigger holes cone cutters or stepped drills are better but run slow . Hacksaw blades generally use Starret .
An old boy I used to work with at a little engineering place taught me how to sharpen drills, which has stayed with me for the most part. Although you do need a steady hand, and a fine grinding wheel. I do struggle with smaller drills though.. anything under about 4 mm I just butcher, then buy a new one lol
As said previously, pressure seems to be the the be all and end all of steel drilling. I don’t really care what sized bit you use, get loads of pressure behind it and drill so you can watch it turning and you can watch the swarf abseiling from the bit. Use mechanical means to add applied pressure and it’ll be plain how much it Improves. A nice thin oil lubricant also helps but this I just can’t get a hang of as to why it works and why it should be so. As far as drill bits goes, the middle of Lidl bits are pretty fab for the money. Anything requiring repeated efforts like spotwelds etc the De Walt extreme are wonderous if the slow and pressurised method is employed . As far as sharpening, I use a pair of mole grips and clamp the to the bit to ensure you get the same cut on each side and that’s all you really need whether it be a deep grind or a low grind using an old bench grinder with a set rest that you can guage the angle to be the same. Ozziedog,,,,,,,' I ,,,,, need this pressure on !!
Hacksaw, the best tool to cut a non straight cut, They don't like to be used, they are a lazy tool, will happily sit in the tool draw doing nothing, when you do want to use it it cuts wonky on purpose so it can sit in the draw do nothing again, I use an axe now ,
The picture I posted just above with that 240 red drill. I’ve chocked the tipping point / fulcrum to about level with some four by four and some nice big foot squares of inch ply, the actual lever is a piece of six by two inch timber about five or six feet long. I’ve set up so I can hold the drill and the speed on the trigger to only just moving and I’m increasing the leverage and pressure once I’ve started the drill moving by my foot on the end of the timber lever. Moving so slowly will quickly burn an electric drill out so I let it do a couple of revolutions then release the pressure and spin the drill with no load on to let the fan cool it down for an instant just every so often. I was drilling out the rear most bolt on the rear bumper iron because it and it’s captive nut were both just spinning . It was right in the iron and near the tow bit of iron too so I couldn’t get a drill bit and the drill chuck straight on it. So I’d been pondering how to do this for a while and this is what I came up with. I used a spring loaded centre punch to start the hole halfway between the centre point and the bolt head edge. Then I drilled with an eighth drill on an angle hopefully toward the middle of the bolt. Same again with a three sixteenth then a quarter bit and finally a fife sixteenth bit and here’s the result. View attachment 136 Ozziedog,,,,,,,,,,never but never have I struck so lucky
Hole saws… now there is a tool that rarely works twice in my hands… I now need to drill a 2 and a bit inch hole in some 1/4 plate to make an exhaust flange.. I’m tempted to buy a front section of exhaust just to cut the flange off it. Flange.
When I had to do similar I driller a smaller hole and enlarged it with a carbide bit. It wasn't as bad as I thought it would be, those carbide bits really chew through steel.
Speed feed and pressure, I can blunt a drill bit in seconds if I try or it will last years if I try properly, most folks drill far to fast , slow it down apply a bit more pressure, decent drill bits help so look at the cut when choosing, remember the cheap ones are cheap for a reason
