I need to drill some 4mm sheet steel, but am having no luck on tries 1
1 was with a general purpose drill bit, which became blunt in about 2
minutes, and the end bue/black from the heat.
2 was with a tunsten carbide masonry bit, which survived ok but was
unusably slow. It produced fine powder very very slowly. 20 minutes of
drilling got most of the way through one hole.
What kind of bit should I be using? Or where else am I going wrong?
The drill is a decent mains one. I'm not really set up for driling
Use a decent quality HSS bit. You don't mention the drill size, but your
drill speed should be around 700 rpm for a 1/2" bit, up to 1500 rpm for a
1/4" hole in mild steel. For a hole of 4mm depth I would also use some
coolant, ideally soap oil but for a one off any thin machine oil like 3 in 1
will do. If you are set up correctly you should get through that hole in
less than 20 seconds!
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 ฃ20.
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 (www.pumaracing.co.uk)
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.
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
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.
*There are two sides to every divorce: Yours and shit head's*
Dave Plowman email@example.com London SW 12
Although answering this, I am not entirely sure this is not a wind-up. Can
you convince us it is not?
Frankly, if you do convince us it is not, then many on this group will be a
little worried that you are practicing DIY on a property that someone may
(God help them) buy from you. I honestly don't mean to ridicule you here,
but what you say does encourage it. Also, before any flaims come in, I am
not intending to be rude. But I am sure I am not the only one smiling wryly
at the mo.
I agree that you are most certainly not set up for drilling steel.
20 minutes drilling to get most of the way through a single hole? Masonry
bit to drill 4mm steel? Good grief!
I can see why you might have (mistakenly) tried the 'general purpose' bit,
but did you not think 2 minutes a little long to keep going for? I suppose
it is not as long as 20 minutes.
Two things you might want to check before you drill anything, ever again,
(1) which direction the drill is rotating in
(2) the time when you start - if you notice the hour hand moving, stop
OK, fun over. Assuming you really did miss the fact that a masonary drill
might be for masonary and not 4mm steel, what you need is a small diameter
drill bit suitable for steel. No more than 2mm, drill a hole, then drill
another with a 4mm bit suitable for steel. Those marked HSS - High Speed
Steel, should do the job.
For future work, remember the old saying "Give us the tools and we'll do the
job" or something similar I remember my old Dad muttering when I was a lad
Winston Churchill said that when asking for US equipment to fight the
Germans. They didn't give us the tools, they sold us them with interest
bankrupting the country as the British were fighting their war, holding back
the Germans until the US rearmed. We fought their war, to give a breath
space, with their tools and they charged us and we ended up poverty
stricken; ask anyone being brought up in the 1940/50s of the austerity in
the UK. Something wrong there me thinks.
Now if we had better high speed drill we would not have needed the Yanks
Checked by AVG anti-virus system (http://www.grisoft.com ).
Version: 6.0.552 / Virus Database: 344 - Release Date: 15/12/2003
I think you will find that the second world war was a continuation of
If you think drilling mild steel with a maonry bit is a little ott wait
until you find out what that traitor Churchill was using for a labourer
to build his wall.
(Despite the fact that the country was being run by Cons in the 30's, it
took a real hero to give Poland to Joseph Stalin.)
Posted via Mailgate.ORG Server - http://www.Mailgate.ORG
Actually, he speaks an awful lot of truth here. It is a fact that
Roosevelt made the UK liquidate ALL its US assets to pay for the
materials they supplied.
I think it took until 1990 until holdings by UK companies in the USA
regained their original level.
N. Thornton has posted many times in this group, and has showed no
I'm smiling wryly, too, because I've BTDT, and it may be the toffee
drills I innocently bought, or the kryptonite I was trying to drill, or
lack of knowledge, but I certainly recognise the situation. I've always
booked this as a group where people come who need (and usually get)
advice not ridicule, and I hope such will not be put off by folks like
Hey Mike - "folks like you" ? What is that? Whatever you are hinting at I,
too, certainly hope that people are not put off by it.
Sorry to have tried to introduce a little humour here. Come on though - if
the thought of someone drilling away at a piece of steel for 20 minutes
doesn't make you chuckle, then maybe you are taking the wonderful world of
DIY a little too seriously. And with DIY, that is probably the biggest
mistake anyone could ever make, if only due to Murphy's Law....
I tried to make a point of saying I was being good humoured about the
winding-up. I guess here lies another example of the drawbacks of text
Best regards to all, including the OP.
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.
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
Er! What's that about unedcurmutated and innumerably innumerate?
See W.W.II Grandmas Buggins, "Ingrediments" and "Reconstituated"
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).
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