Drilling 4mm Steel

I think you mean, "give us the job and we'll finish the tools"

Reply to
stuart noble
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Those speed recommendations appear to exactly agree with my copy of the Dormer Twist Drill and Reamer Handbook recommendations for the lowest grades of mild steel. But, those are speeds for optimised conditions in high speed production environments i.e. rigid machinery setups, drills in perfect condition, the correct coolant/lubricant. They also balance the cost of replacing/resharpening the drills on a regular basis with the need to get fast throughput which means running faster than the drill bit would ideally like to survive forever. For DIY use, especially with hand tools you can forget them. In fact halving them isn't too much. Even on my milling machine if I want my drills to last for the sake of taking a few seconds more I rarely run at more than 550rpm with drills of the 8mm to 10mm range. I hardly ever have to resharpen a drill because I don't burn them out.

For a hole of 4mm depth I would also use some

To the OP. The average hand power drill runs far too fast for drilling in steel, even mild steel. If you have a variable speed control then wind it down as far as it will go but it will still probably be too fast. A few hundred rpm is ideal and only special high torque/low speed drills do that. Drill bits burn out in seconds when they run too fast.

Buy decent quality HSS drill bits. Go to your local Engineers Merchants (yellow pages) and see what they have on special offer. Kamasa, Dormer, anything German is what the pros use in engineering shops. Forget Halfrauds and other mickey mouse car bits suppliers. You can often get a set of quality 1mm to 10mm drills in 0.5mm increments for under £20.

Use a centre punch to locate the drill bit and start with a small drill, say

5mm, which will be better suited to the over fast power drill. Then work up in 2mm increments to enlarge the hole. Use a squirt of any sort of oil to cool and lubricate the cut. Engine oil is ok at a pinch. Having said that I run dry on the mill because oil makes the swarf stick to everything but then I'm running at very slow speeds and on a rigid machine. I'll drill through every 1mm in a couple of seconds without ever burning a drill out.

Get a good quality drill bit at the right speed and you'll wonder why you ever had a problem because it'll cut mild steel like butter.

Dave Baker - Puma Race Engines

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I'm not at all sure why women like men. We're argumentative, childish, unsociable and extremely unappealing naked. I'm quite grateful they do though.

Reply to
Dave Baker

I hesitated to say this against the advice of those much more skilled than me, but on my own cheap (40 quid) B&Q pillar drill I leave it on the low speed for everything. I've not developed the art of sharpening small drills, and although they're cheap enough that doesn't help if you need one *now*.

Luckily, with most mains drills, enough pressure will slow them down considerably, and a pause to let things cool down will help too.

One good source of small drills is autojumbles - you'll get a pack of ten designed for production use for the cost of one from a shed.

Reply to
Dave Plowman

Well thanks to all I'm now the proud owner of a nice new set of holes :) Cheers!

PS I did em with unmarked bright steel drills, couldnt find the HSS ones for some reason.

Regards, NT

Reply to
N. Thornton

"Kalico" wrote in news:K3NEb.3062$ snipped-for-privacy@wards.force.net:

I regret it if I jumped too quickly, it wasn't d-i-y I take that seriously, it's this group; usenet is full of very abusive and sneery types, and this group is usually pretty gentle on the uninformed; I am prolly overanxious to keep it that way.

mike r

Reply to
mike ring

I am keen to keep it that way too. One need only check my past posts to see how gentle I am on beginners. Hell, I even work as a teacher, so sneeriing at the uneducated is not something that would come easily to me.

Merry Christmas Mike Rob

Reply to
Kalico

Glad you saw the funny side of your original post.

Anyway, most important thing is - have you had more success with another HSS drill bit? If not, and it is still taking ages (ok, 2 mins not really too long) then it could be a bit more than mild steel

All the best Rob

Reply to
Kalico

Not like the teachers I remember, then?

Reply to
Dave Plowman

Dave Plowman wrote in news: snipped-for-privacy@argonet.co.uk:

Not at East Ham Grammar in the fifties, either.

Course, we did end up educermated and numeramate

mike r

Reply to
mike ring

I hope _you_ are kidding. I don't take that long to put a 5mm hole down the centre of a 6mm x 100mm long piece of 416 stainless steel.

Colin Bignell

Reply to
nightjar

Looks like our favourite president George W has started posting!

Reply to
Kalico

"Kalico" wrote in news:cblFb.3595$tQ6.42669 @wards.force9.net:

Not acquainted with Homer J Simpson, then? Have a donut.

mike r

Reply to
mike ring

Hi, In case you didnt see my reply, yes, all done ty.

Regards, NT

Reply to
N. Thornton

No, I've done many holes that have taken over 2 minutes, mostly in brick or concrete. Even the 4mm took over 2 minutes a hole, but done it surely was.

Regards, NT

Reply to
N. Thornton

Who's him?

Er! What's that about unedcurmutated and innumerably innumerate?

See W.W.II Grandmas Buggins, "Ingrediments" and "Reconstituated" etc.!

Also; my late father, a teacher in the UK for about 40 years, said that a common 'Teachers Common Room' joke was about "Casting sham pearls of wisdom before real swine"!. Oh gosh; that included all of us pupils! :-) (Escaped from the school system in 1952). Terry.

Reply to
Terry

I suspect you need to either buy a drill sharpener, or buy a more powerful drill, or get a chart of drill speeds. The only holes I recall taking that long were the ones I cut with core drills for the bathroom wastes and for the fan. However, each included going outside and up a ladder, to drill from that side, once the guide drill had broken through.

Colin Bignell

Reply to
nightjar

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