Drill bits

single

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Is there a make of drill bits that actually work? I'm doing a load of stainless steel things and whatever i use seems to take forever.
 

ostell

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What you trying to use at the moment? HSS?
You need a special for stainless steel, cobalt bits, but you drill slowly, carefully, with constant pressure and some cooling.
 

macd

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Makita cobalts at the moment with lube but they seem rubbish.
HSS is perfectly good for stainless steel. Above all you need:
1. sharp bits;
2. heavy pressure;
3. low speed;
4. lubrication/cooling (nothing special for occasional jobs: light oil will do);
5. no excessive heat build-up (to which all the above contribute);
6. patience.

Excessive heat work-hardens the steel, and then the job's b**gered.
 

30boat

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Are you using a pillar drill? Stainless needs a lot of pressure which is hard to apply without one. I use old oil for lubricant but cutting oil is better.
 

rob2

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It's a knack to get it right and I'm currently out of practice! All the above advice is correct yet it's easy to believe the bit is no good if you don't get it right at the start as the dimple you create will immediately heat treat itself to an almost undrillable state, so don't stint on the cooling and don't attempt it with a single speed pistol drill as that will be too fast regardless of drill size.

Rob.
 

Richard10002

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I bought some Dormer drill bits a few years ago for some steel and stainless steel work a few years ago. Worked very well and stayed sharp.
 

rogerthebodger

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HSS is OK an any HSS make will do. The trick over and above what as been said is to ensure the drill is cutting and not just rubbing.

Either a pillar drilling machine or if with a hand held electric drill I tend to used my battery drill which I find is about the right speed where as a mains drill tend to be too fast even on its slowest speed.
 

single

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I bought some Dormer drill bits a few years ago for some steel and stainless steel work a few years ago. Worked very well and stayed sharp.

I've just been looking at Dormer but bloody expensive. I suppose it might be worth it in the long run.
 

bill bligh

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As above slow speed firm but not too much pressure (drill bit will over heat) cutting fluid. Also you tube (sharpening Hss or twist drill bits) you will save money and time once you have learnt how.
 

BobnLesley

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An acquaintance and steel fabricator advised me years ago that there was a lot of rubbish talked about 'special' drill bits and that all you needed for stainless was 'a half-way decent hss bit that is SHARP' ever since I've tended to start a job by sharpening several drill bits and using each for no more than one or two holes before replacing; re-sharpening the lot if/when I run out.
The other 'trick' I've discovered, though by luck rather than good management, is to use an 18.8 volt cordless drill on its slow-speed setting', but rather than fitting the battery, connect it to a 12-volt one, this gives a lovely speed for drilling stainless.
 

single

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An acquaintance and steel fabricator advised me years ago that there was a lot of rubbish talked about 'special' drill bits and that all you needed for stainless was 'a half-way decent hss bit that is SHARP' ever since I've tended to start a job by sharpening several drill bits and using each for no more than one or two holes before replacing; re-sharpening the lot if/when I run out.
The other 'trick' I've discovered, though by luck rather than good management, is to use an 18.8 volt cordless drill on its slow-speed setting', but rather than fitting the battery, connect it to a 12-volt one, this gives a lovely speed for drilling stainless.

I just came to that conclusion.Some new HSS bits were better than used cobalts. Speed isn't any problem, it's very controllable with the cordless Makita.
 

Heckler

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I bought some Dormer drill bits a few years ago for some steel and stainless steel work a few years ago. Worked very well and stayed sharp.

I did the same, searched on Ebay SS drill bits, £3 ish for 1/8" ish sizes. Got a short spiral with a strange edge on them. Worth every penny. Slow, lube, heavy pressure.
S
 

PCUK

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Teach yourself to sharpen your bits on the bench grinder and you'll never need 'special' bits again. I make mine very coarse and they rip through stainless like butter.
 

Avocet

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Teach yourself to sharpen your bits on the bench grinder and you'll never need 'special' bits again. I make mine very coarse and they rip through stainless like butter.
I wish I could do that! I consider myself a failure as an engineer because I can't (repeatably) get them right. Every now and then I get one right and it works very well, but most of the tim, the results are "variable"! I just have a real blind spot when it comes to drill sharpening!

On the OP's point, my thoughts are:
(a) I've got some Makita drill bits that were part of a (remarkably cheap!) set of drill and driver bits. They're pretty rubbish. I was surprised for something with Makita's name on it to be honest. I don't know whether they use lower quality stuff in their "bargain bucket" promotions though.
(b) As others have said, Dormer drills are excellent. I also like Presto.
(c) It wil lbe almost impossible to put "too much" pressure on any drill of diameter 8mm and above if just using a hand drill.
(d) As has also been said, slow is good. Once the drill starts to "polish" the workpiece, you've had it - literally a couple of seconds and the drill bit is toast.
 

lw395

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I wish I could do that! I consider myself a failure as an engineer because I can't (repeatably) get them right. Every now and then I get one right and it works very well, but most of the tim, the results are "variable"! I just have a real blind spot when it comes to drill sharpening!

On the OP's point, my thoughts are:
(a) ......(d) As has also been said, slow is good. Once the drill starts to "polish" the workpiece, you've had it - literally a couple of seconds and the drill bit is toast.
The trouble is, a lot of the things yotties want to drill is pre-abused, work hardened ss.
So cobalt drills earn their keep.
Carbide drills sold for tiles can be good too.
 

DinghyMan

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HSS or TIN/Nitride coated HSS are better than Cobalt for stainless steel. Cobalt is OK for spotting drills and countersinks but don't buy cheap stuff - look for cncpoorboy on Ebay.

Follow macd's suggestions above.

Do not centre punch before drilling as you are just adding a work hardened area directly where you want to drill.

I work with a lot of stainless that has been bent and work hardened and a piller drill with plenty of pressure, spotting drill, sharp drills, and plot holes and it drills almost as easily as mild steel. On the lathe I drill 50mm plus with <6mm drills regularly using cheap and cheerful bulk buy HSS bits from UK Drills on Ebay
 
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