drilling steel?

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Just to say thanks for all the help.....
I got a new drill with variable speed, a Champion 750W from Focus, a new B&D Bullet drill and used some cheap engine oil i had laying around as lub. Decided that although in theory the drill had a 2 speed range setting that the slowest was still too fast for the 12mm drill bit, so I held the trigger, pushed the drill down fairly hard and drilled pretty slow, while my helper sqirted oil on the work. What a difference! It was amazing...... cut though the steel easy :)
Thanks again
Dave PS The work was clamped in a vice under a wolfcraft drill stand, which was clamped to a B&D workmate. All seemed pretty solid and safe'ish!

a
Does
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I've got the tee shirt for that, but it was a long time ago :-) I've drilled many metals since then and have learned a lot about the subject.

I'm not sure about the quality of that drill, but see later.

a
The maximum speed you quote is for best conditions. 1000 RPM is a bit fast for the average home user.

Does
Some one else has said that you should pilot hole the metal by using a smaller drill, followed by a larger one. Good advice. When you come to drill the hole to the size you want, you will need a much slower drill rotation speed. The only way to do this, is to start and then stop the power to the drill, thus keeping the rotation speed down. This will be hard on the power tool, but kind on the twist drill. If the power tool heats up, take a break till it cools down.
By keeping a heavy pressure all the time, on the drill, (very important you keep lots of pressure while cutting the hole) on the power drill, to ensure that you continue cutting, you will be better off starting and stopping the drill by flicking the switch on every few moments. This keeps the rotational speed down and will prevent the cutting edge of the drill from blunting through heat.
HTH
And I hope you understand what I am saying :-)
Dave
Dave
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wrote:

I agree that this is the best way, provided your drill motor has enough power to do it. The problem comes when you don't have enough power to let you push hard enough to get a sufficient bite. Then the bit just spins and dulls. A clue you aren't pushing hard enough is when you don't get nice curls coming off the bit as you drill. If you're just getting piddly little shavings, you aren't feeding aggressively enough, and the bit dulls prematurely. If the motor stalls when you push hard enough, you don't have enough motor (or it's geared too high) to let you drill that hole.
Gary
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On Sat, 30 Aug 2003 08:30:30 +1200, Bruce Simpson

A lot depends on the hole size, and the rigidity of your drill press / hand drill.
If you try to drill 13mm straight off with a hand drill, then there's the potential for so a slight difference in cut depth from side to side turning into a considerable off-axis force. The hole is likely to wander like crazy, possibly with injury.
If you're drilling on a rigid drill press, then even then you can have problems with thin sheet (and I mean <16 gauge) deforming beneath the drill bit.
Personally I like to use a stepped drill or similar for this sort of work (HVAC ?) You not only drill a pilot hole, you use it to guide the next drill step.
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When drilling thin stock, it's hard to beat a step drill. Makes a rounder hole (more round?) and is far less likely to snatch the material.
John
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On 30 Aug 2003 07:56:21 -0700, snipped-for-privacy@cbpu.com (JohnM) wrote:

What are you drilling these holes with? Bench drill or what? I'm not an expert but make sure you lubricate the bit, use even pressure, drill a pilot hole(!), use a properly sharpened or new bit, keep the revs down. It *is* mild steel you are drilling isn't it? Sure? Maybe try working up to that size using smaller bits.
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Better still to use a Q-Max type punch. Although IIRC 3 mm steel might be a bit much.
--
He who laughs last, thinks slowest.

Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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buy a pillar drill. Get some good quality metal drills, I bought a set from machine mart for about 30, sizes from 1mm to 13mm. Skimping on equipment will get you nowhere.

a
Does
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