Hiya

I have just tried drilling some 3mm thick mild steel with a 13mm
hole......... hell of a lot of noise, loads of vibration and now the drill
seems to do anything but drill!

Ok, please stop laughing, I'm a beginer!!

The drill bit was a Piranna 'Bullet' that it said was for drilling metal,
but what I have only just realsied is that the max recomended rpm for 10mm
was about 1000. The drill was the cheapest Clarkes one speed drill (i'm on a
budget and this might be a '1 of' project) so I guess this is much faster.

So my questions a
Is the drill running too fast? What speed should i drill 12mm holes at? Does
anyone know where I can the cheapest drill to drill at the recommended
speed?

Thanks for any help given

Dave

"Dave" wrote in message
...
Hiya

I have just tried drilling some 3mm thick mild steel with a 13mm
hole......... hell of a lot of noise, loads of vibration and now the drill
seems to do anything but drill!

Ok, please stop laughing, I'm a beginer!!

The drill bit was a Piranna 'Bullet' that it said was for drilling metal,
but what I have only just realsied is that the max recomended rpm for 10mm
was about 1000. The drill was the cheapest Clarkes one speed drill (i'm on
a
budget and this might be a '1 of' project) so I guess this is much faster.

So my questions a
Is the drill running too fast? What speed should i drill 12mm holes at?
Does
anyone know where I can the cheapest drill to drill at the recommended
speed?

Thanks for any help given

Dave

May I answer two questions you haven't asked?
1. Use a lubricant, old engine oil will do, and it will save your drill
bit
2. Fix (clamp) the sheet of steel and be prepared for a 'snatch' when
you break through.
BAH

Dave wrote:

Hiya

I have just tried drilling some 3mm thick mild steel with a 13mm
hole......... hell of a lot of noise, loads of vibration and now the drill
seems to do anything but drill!

Ok, please stop laughing, I'm a beginer!!

The drill bit was a Piranna 'Bullet' that it said was for drilling metal,
but what I have only just realsied is that the max recomended rpm for 10mm
was about 1000. The drill was the cheapest Clarkes one speed drill (i'm on a
budget and this might be a '1 of' project) so I guess this is much faster.

So my questions a
Is the drill running too fast? What speed should i drill 12mm holes at? Does
anyone know where I can the cheapest drill to drill at the recommended
speed?

Thanks for any help given

Dave

I'd aim to use lkess than 1000rpm for 12mm but you are where you are and have
only one drill speed.
Clamp the work firmly onto a sacrificial piece of wood. the workmust not deflect
away fromthe drill bit. This is possibly where your noise is coming from.
For mild steel, a quality brand drillbit (dormer etc) is all you should need.
Use a pilot drill say about 4mm followed ideally by something around 8mm.
As a minimum, the pilot drill should allow the chisel portion of the next drill
to pass into the pilot hole.
Often helps to put some oil when drilling.

Good luck

Bob

In article ,
Dave wrote:
The drill bit was a Piranna 'Bullet' that it said was for drilling
metal, but what I have only just realsied is that the max recomended rpm
for 10mm was about 1000. The drill was the cheapest Clarkes one speed
drill (i'm on a budget and this might be a '1 of' project) so I guess
this is much faster.

IIRC, most single speed drills run at about 2400 off load - but you
should be able to slow it down quite a bit on load.

--
*Starfishes have no brains *

Dave Plowman London SW 12
RIP Acorn

On Thu, 28 Aug 2003 20:21:50 +0000 (UTC), "Dave"
wrote:

I have just tried drilling some 3mm thick mild steel with a 13mm
hole......... hell of a lot of noise, loads of vibration and now the drill
seems to do anything but drill!

You're pretty lucky it didn't decide to spin the metal, rip a hole in
your leg and leave you bleeding to death from a femoral artery ! 8-)

13mm isn't a small hole in thin steel. Now I'm a cowboy, but even I
don't like to drill that with a handheld drill. If I have to, I do
make sure it's clamped down pretty well. If I don't have a slow power
drill, I'll do it by hand. I am _not_ going to over-speed a big drill
bit into something that's likely to fly up and tear chunks out of me -
Sorry, done that one far too many times already.


Use lubricant. Something oily is good. Buy some RTD if you want (it's
gooey enough not to run away from a hole in a wall), but old engine
oil is a lot better than nothing.

Drill a pilot hole. You should be able to fit the centre chisel edge
of the bigger drill into the existing pilot hole.

Use a backer - bit of scrap wood clamped on the back, or something. If
you don't do this, then it's going to go completely random when you
break through,

Go slow. For 13mm, go damned slow.

Use decent drills. The shed sets are garbage. Go to a real engineer
and get some black ones (you're in the UK - buy some Presto), not the
Chinese gold-coloured TiN ones.

Don't drill 13mm holes in thin sheet with a handheld twist drill. Get
a Conecut or something if you're going to make a habit of it. A
two-flute drill that isn't held rigidly gives you a lousy hole that's
probably more pentagonal than round.

"Andy Dingley" wrote in message
...
....
Use decent drills. The shed sets are garbage. Go to a real engineer
and get some black ones (you're in the UK - buy some Presto), not the
Chinese gold-coloured TiN ones.

The colour is not really a guide. The TiN coating reduces friction and can
be applied to any quality of drill. I would, however, agree that you don't
want to buy any drills made in the Far East.

... A
two-flute drill that isn't held rigidly gives you a lousy hole that's
probably more pentagonal than round.

For a two-flute drill it will be triangular, rather than pentagonal - that
would require four flutes. Polygonal holes are always drilled using one less
flute than the number of sides you want to end up with.

Colin Bignell

Dave

1000rpm is way too fast. You should be running at 750 (ish)rpm in mild
steel if using high speed steel (HSS) twist drill but slower, say, 220 (ish)
rpm if using carbon steel twist drill (yes, they're still around). Other
posted advice is good about pilot holes, clamping and coolant, but don't use
water as this can cause small checks or cracks which may result in the twist
drill tip chipping out. You may have knackered your 13mm twist drill so a
re-grind may be necessary - check for dullness of the tip and wear to the
extreme outer corners of the cutting edges (a sure sign/confirmation of too
high a speed).

Speeds and feeds for any type of metal cutting is a complex business.
Factors such as type of material to be cut, the type of drill, the kind of
steel in the drill, the design & condition of the drilling machine, the
shape & sharpness of the drill point and the coolant used.

The 'economy' drilling machines affordable by DIYers mostly have limited
speed ranges (& usually excluding slows!), acceptable for lots of jobs in
timber, plastic, most non-ferrous, & 'light' steel work. They're clearly
not designed for heavy duty work. But if you follow earlier advice about
pilot holes (lots of them getting bigger in stages 'till you reach 13mm) you
should get away with this job.

Best of luck

Paul

This may assist you in your quest...
http://www.wwch.org/TechData/DrillBitSpds.htm

Jesse L Zufall
Silt Colo

---- ****----
If at first you don't succeed, skydiving is not for you.
"Dave" wrote in message
...
Hiya

I have just tried drilling some 3mm thick mild steel with a 13mm
hole......... hell of a lot of noise, loads of vibration and now the drill
seems to do anything but drill!

Ok, please stop laughing, I'm a beginer!!

The drill bit was a Piranna 'Bullet' that it said was for drilling metal,
but what I have only just realsied is that the max recomended rpm for 10mm
was about 1000. The drill was the cheapest Clarkes one speed drill (i'm on
a
budget and this might be a '1 of' project) so I guess this is much faster.

So my questions a
Is the drill running too fast? What speed should i drill 12mm holes at?
Does
anyone know where I can the cheapest drill to drill at the recommended
speed?

Thanks for any help given

Dave

Thanks for the help people

BTW

Didnt rip my leg open as the hand drill is in a stand with the work clamped
I'm a beginer but i can remember back to my metal work days at school!

cheers
dave

PS wont a power drill that allows screwdriving, or a variable speed drill be
able to run at slow speed?


"Dave" wrote in message
...
Hiya

I have just tried drilling some 3mm thick mild steel with a 13mm
hole......... hell of a lot of noise, loads of vibration and now the drill
seems to do anything but drill!

Ok, please stop laughing, I'm a beginer!!

The drill bit was a Piranna 'Bullet' that it said was for drilling metal,
but what I have only just realsied is that the max recomended rpm for 10mm
was about 1000. The drill was the cheapest Clarkes one speed drill (i'm on
a
budget and this might be a '1 of' project) so I guess this is much faster.

So my questions a
Is the drill running too fast? What speed should i drill 12mm holes at?
Does
anyone know where I can the cheapest drill to drill at the recommended
speed?

Thanks for any help given

Dave

On Fri, 29 Aug 2003 02:03:14 +0100, nightjar wrote:

The colour is not really a guide. The TiN coating reduces friction and can
be applied to any quality of drill.

I used to like TiN coatings. I have some old ones here (German,
AFAIR) that are still in excellent condition after much use.

But the common TiN sets around now aren't worth a damn. As a general
rule of shopping, I'd avoid the colour entirely unless you're
absolutely sure of the quality. A TiN coating (even a good one) adds
little for most DIY users, until you're into production work on tough
metal. How many drills do any of us really _wear_ out, compared to
loss or breakage ?

The cobalt drills are even worse ! The "coated" sets with the blue
rainbow finish (mine came form Northern Tools) are absolute rubbish.
OTOH, a real set (from Axminster) of silver-coloured M42 steel were a
great addition to the workshop.

I would, however, agree that you don't
want to buy any drills made in the Far East.

My Japanese stuff is good. I'm sure that both the Chinese sources
could do better too, if there was a call for it - but "cheap sets for
DIY sheds" are always going to be intended to be cheap, not high
quality.


For a two-flute drill it will be triangular, rather than pentagonal - that
would require four flutes.

I'd agree that large holes in sheet tend to the triangular, or more
likely torn and oval during breakthrough.

But I've definitely had chatter in a drillpress, probably caused by
drilling a pilot hole larger with a blunt drill, used too fast, and
these have been pentagonal.

"Dave Plowman" wrote in message
...
In article ,
Dave wrote:
The drill bit was a Piranna 'Bullet' that it said was for drilling
metal, but what I have only just realsied is that the max recomended rpm
for 10mm was about 1000. The drill was the cheapest Clarkes one speed
drill (i'm on a budget and this might be a '1 of' project) so I guess
this is much faster.

IIRC, most single speed drills run at about 2400 off load - but you
should be able to slow it down quite a bit on load.

It doesn't slow down enough. I've spent a while blunting bits
with a single speed B and D before borrowing bu FiL's
Lidl special offer with a gearbox which was much easier.
Even a cheap Argos with a lockable trigger is better.

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!

"Dave" wrote in message
...
Hiya

I have just tried drilling some 3mm thick mild steel with a 13mm
hole......... hell of a lot of noise, loads of vibration and now the drill
seems to do anything but drill!

Ok, please stop laughing, I'm a beginer!!

The drill bit was a Piranna 'Bullet' that it said was for drilling metal,
but what I have only just realsied is that the max recomended rpm for 10mm
was about 1000. The drill was the cheapest Clarkes one speed drill (i'm on
a
budget and this might be a '1 of' project) so I guess this is much faster.

So my questions a
Is the drill running too fast? What speed should i drill 12mm holes at?
Does
anyone know where I can the cheapest drill to drill at the recommended
speed?

Thanks for any help given

Dave

On Fri, 29 Aug 2003 11:59:09 +0100, "Nick Finnigan"
wrote:

"Dave Plowman" wrote in message
...
In article ,
Dave wrote:
The drill bit was a Piranna 'Bullet' that it said was for drilling
metal, but what I have only just realsied is that the max recomended rpm
for 10mm was about 1000. The drill was the cheapest Clarkes one speed
drill (i'm on a budget and this might be a '1 of' project) so I guess
this is much faster.

IIRC, most single speed drills run at about 2400 off load - but you
should be able to slow it down quite a bit on load.

It doesn't slow down enough. I've spent a while blunting bits
with a single speed B and D before borrowing bu FiL's
Lidl special offer with a gearbox which was much easier.
Even a cheap Argos with a lockable trigger is better.

I've found that the judicious application of some off/on/off/on
trigger work can provide what amounts to a lower spindle speed even on
a cheap single-speed electric hand-drill.


--
you can contact me via http://aardvark.co.nz/contact/

On Fri, 29 Aug 2003 01:39:45 +0100, Andy Dingley
wrote:

Use lubricant. Something oily is good. Buy some RTD if you want (it's
gooey enough not to run away from a hole in a wall), but old engine
oil is a lot better than nothing.

Is it?

When I was out of cutting lube I trued using a squirt of Mobil 1 once.

It was really bad. The drill would not "bite", despite the
application of significant pressure -- and then when it did bite --
well fortunately the work was clamped really well (as it always is in
my shop ;-) so the drill-press stalled (only 3/4HP and a 12mm drill
bit).

It would appear that the film-strength of a good motor oil (a
synthetic anyway) is too high for it to function as a good cutting
oil. I would assume that cutting oil should be designed to have a
relatively low film strength so as to allow the cutting edge to reach
the work and actually do some cutting -- rather than skating around in
a thin film of oil.

But, given that I'm not an industrial chemist, I might be completely
wrong.

However, if you've got some synthetic motor oil in your shop, try
using some as cutting oil and see what happens.

--
you can contact me via http://aardvark.co.nz/contact/

On Fri, 29 Aug 2003 02:03:14 +0100, nightjar wrote:


"Andy Dingley" wrote in message
.. .
...
Use decent drills. The shed sets are garbage. Go to a real engineer
and get some black ones (you're in the UK - buy some Presto), not the
Chinese gold-coloured TiN ones.

The colour is not really a guide. The TiN coating reduces friction and can
be applied to any quality of drill. I would, however, agree that you don't
want to buy any drills made in the Far East.

Correct -- and the black ones you buy here are made of pewter I swear
(well I swear at them anyway).

One brand sold here seem to use black oxide on their really poor
quality (ie: either soft as butter or brittle as ice) drill bits. I
steer well clear and just stick to a known brand of good quality HSS
(for most metals) or cobalt (for stainless).
--
you can contact me via http://aardvark.co.nz/contact/

On Fri, 29 Aug 2003 01:58:07 GMT, Jim K
wrote:

Make sure you don't have the drill in reverse. I've done that before
and it makes you feel real stupid when you finally notice.

Actually, a TV ad for a really crappy brand of TiN-coated drill bits
here in NZ was dumb enough to do a "conventional drill-bit versus
*our* titanium drill bit" comparison. Of course the titanium drill
went straight through the piece of 1" square-section -- whereas the
conventional bit just spun, hardly making a mark.

It didn't take a rocket scientist to spot however, that the
conventional drill bit was spinning the wrong way!

I checked out a set of these "titanium" drills and they were crap.
Not only was the titanium coating already starting to rub off while
they were still in tbe box, but the angles were uneven and there were
actually coarse grinding marks visible. I swear they look as if they
were ground by hand on some old foot-operated grinding stone.

I heard from someone else who actually bought a set that they *bent*
two of the bits through about 70 degrees simply by applying a normal
amount of pressure.

Fortunately these drills have a 30 day money-back/replacement
guarantee but I suspect that most of those stupid enough to buy them
are only drilling stuff like softwood where they must last at least 30
days of occasional use ;-)

--
you can contact me via http://aardvark.co.nz/contact/

"Dave" wrote in message
...
Hiya

I have just tried drilling some 3mm thick mild steel with a 13mm
hole......... hell of a lot of noise, loads of vibration and now the drill
seems to do anything but drill!

Ok, please stop laughing, I'm a beginer!!

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.

The drill bit was a Piranna 'Bullet' that it said was for drilling metal,

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

but what I have only just realsied is that the max recomended rpm for 10mm
was about 1000. The drill was the cheapest Clarkes one speed drill (i'm on
a
budget and this might be a '1 of' project) so I guess this is much faster.

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

So my questions a
Is the drill running too fast? What speed should i drill 12mm holes at?
Does
anyone know where I can the cheapest drill to drill at the recommended
speed?

Thanks for any help given

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

On Sat, 30 Aug 2003 08:35:44 +1200, Bruce Simpson wrote:
On Fri, 29 Aug 2003 01:39:45 +0100, Andy Dingley
wrote:
Use lubricant. Something oily is good. Buy some RTD if you want (it's
gooey enough not to run away from a hole in a wall), but old engine
oil is a lot better than nothing.

Is it?

When I was out of cutting lube I trued using a squirt of Mobil 1 once.

It was really bad. The drill would not "bite", despite the
application of significant pressure -- and then when it did bite --
well fortunately the work was clamped really well (as it always is in
my shop ;-) so the drill-press stalled (only 3/4HP and a 12mm drill
bit).

It would appear that the film-strength of a good motor oil (a
synthetic anyway) is too high for it to function as a good cutting
oil. I would assume that cutting oil should be designed to have a
relatively low film strength so as to allow the cutting edge to reach
the work and actually do some cutting -- rather than skating around in
a thin film of oil.

But, given that I'm not an industrial chemist, I might be completely
wrong.

You aren't wrong. Motor oil is formulated to *prevent* metal to metal
contact. When drilling, you *must have* metal to metal contact in order
for the bit to cut. The main purpose of cutting oil is to *cool* the bit
to prevent it getting so hot it loses its temper. The high sulphur content
also tends to promote shearing action. It is not intended to *lubricate*.

Gary

On Sat, 30 Aug 2003 08:30:30 +1200, Bruce Simpson wrote:
On Thu, 28 Aug 2003 22:51:08 +0100 (BST), "Dave Liquorice"
wrote:
1) Don't try and drill it in one step. Drill smaller hole(s) and
increase in size up to the required 13mm.

Is that really the best way to do it?

I've found that, when drilling thin material such as 3mm, there's
little point (and sometimes a few problems) in drilling more than a
pilot (the size of the web in the final drill-bit) then the final
hole.

Drilling an intermediate hole only seems to encourage chatter and even
a little wandering when the final drill is used.

So long as the web is clear, a drill bit of any size should be able to
do the hole in one fell swoop.

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

In article ,
Bruce Simpson wrote:
When I was out of cutting lube I trued using a squirt of Mobil 1 once.

Good grief. You could have had a drum of the stuff couriered around for
the cost of that stuff. ;-) Talk about black gold.

--
*Eat well, stay fit, die anyway

Dave Plowman London SW 12
RIP Acorn

On Sat, 30 Aug 2003 01:58:17 +0100, Dave Plowman
wrote:

In article ,
Bruce Simpson wrote:
When I was out of cutting lube I trued using a squirt of Mobil 1 once.

Good grief. You could have had a drum of the stuff couriered around for
the cost of that stuff. ;-) Talk about black gold.

Actually, I spend probably about US$9 a year on the stuff for the
workshop. I use it as way-oil, general lube and rust protectant.
It's clean, doesn't smell, works *very* well and a little goes a long
way.

I once made the mistake of using regular mineral motor oil instead --
what a stink -- it took days to come out of my hands.

--
you can contact me via http://aardvark.co.nz/contact/

"Bruce Simpson" wrote in message
...
On Fri, 29 Aug 2003 02:03:14 +0100, nightjar wrote:


"Andy Dingley" wrote in message
.. .
...
Use decent drills. The shed sets are garbage. Go to a real engineer
and get some black ones (you're in the UK - buy some Presto), not the
Chinese gold-coloured TiN ones.

The colour is not really a guide. The TiN coating reduces friction and
can
be applied to any quality of drill. I would, however, agree that you
don't
want to buy any drills made in the Far East.

Correct -- and the black ones you buy here are made of pewter I swear
(well I swear at them anyway).

Yep. I had one unspiral itself when I tried to drill with it. Thinking it
was an isolated fault, I returned it to the supplier and the same thing
happened with the replacement and with the replacement for the replacement,
even though the supplier, a respected specialist supplier of drills to the
engineering trade, assured me that they were all from different batches.

One brand sold here seem to use black oxide on their really poor
quality (ie: either soft as butter or brittle as ice) drill bits. I
steer well clear and just stick to a known brand of good quality HSS
(for most metals) or cobalt (for stainless).

As I mostly use automatic machinery, I prefer solid carbide for stainless.

Colin Bignell

On Sat, 30 Aug 2003 08:35:44 +1200, Bruce Simpson
wrote:

but old engine oil is a lot better than nothing.

Is it?

Yes, it works fine. Note the qualifier "old"

On Sat, 30 Aug 2003 08:30:30 +1200, Bruce Simpson
wrote:

I've found that, when drilling thin material such as 3mm, there's
little point (and sometimes a few problems) in drilling more than a
pilot (the size of the web in the final drill-bit) then the final
hole.

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.

"Dave" wrote in message ...
Hiya

I have just tried drilling some 3mm thick mild steel with a 13mm
hole......... hell of a lot of noise, loads of vibration and now the drill
seems to do anything but drill!

Ok, please stop laughing, I'm a beginer!!

The drill bit was a Piranna 'Bullet' that it said was for drilling metal,
but what I have only just realsied is that the max recomended rpm for 10mm
was about 1000. The drill was the cheapest Clarkes one speed drill (i'm on a
budget and this might be a '1 of' project) so I guess this is much faster.

So my questions a
Is the drill running too fast? What speed should i drill 12mm holes at? Does
anyone know where I can the cheapest drill to drill at the recommended
speed?

Thanks for any help given

Dave

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

In article ,
JohnM wrote:
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.

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 London SW 12
RIP Acorn

Just drilled to holes to mount my mill vise.

I used 450rpm.

First hole with a 1/8 drill.

Second hole with a 3/8 drill.

Steel plate thickness was 8mm.

my 2 cents

"Dave" wrote in message
...
Hiya

I have just tried drilling some 3mm thick mild steel with a 13mm
hole......... hell of a lot of noise, loads of vibration and now the drill
seems to do anything but drill!

Ok, please stop laughing, I'm a beginer!!

The drill bit was a Piranna 'Bullet' that it said was for drilling metal,
but what I have only just realsied is that the max recomended rpm for 10mm
was about 1000. The drill was the cheapest Clarkes one speed drill (i'm on
a
budget and this might be a '1 of' project) so I guess this is much faster.

So my questions a
Is the drill running too fast? What speed should i drill 12mm holes at?
Does
anyone know where I can the cheapest drill to drill at the recommended
speed?

Thanks for any help given

Dave

In article , Bruce Simpson
writes
On Fri, 29 Aug 2003 01:39:45 +0100, Andy Dingley
wrote:
Use lubricant. Something oily is good. Buy some RTD if you want (it's
gooey enough not to run away from a hole in a wall), but old engine
oil is a lot better than nothing.

Is it?

Not really -- use WD40 instead or, failing that, water applied from a
hand spray. Even if the water doesn't lubricate the drill bit, it will
at least help to keep it tolerably cool.

I must admit that, whilst I've not tried it as a drilling coolant or
lubricant, I have used "I Can't Believe It's Not Butter" [1] when
turning stainless steel; it seemed to work reasonably well, though the
workshop stank like a chip shop for days afterwards.

[1] I'd bought two tubs in a B.O.G.O.F. supermarket promotion and, on
tasting it, I soon decided I'd been overcharged on both. There again,
I'd doubt that anyone could pay me enough to *eat* the stuff...

--
Paul

In article , Paul Hewish
writes
1000rpm is way too fast. You should be running at 750 (ish)rpm in mild
steel if using high speed steel (HSS) twist drill but slower, say, 220 (ish)
rpm if using carbon steel twist drill (yes, they're still around). Other
posted advice is good about pilot holes, clamping and coolant, but don't use
water as this can cause small checks or cracks which may result in the twist
drill tip chipping out. You may have knackered your 13mm twist drill so a
re-grind may be necessary - check for dullness of the tip and wear to the
extreme outer corners of the cutting edges (a sure sign/confirmation of too
high a speed).

IIRC, those "Piranha" drills are impossible to regrind to the same
profile and may have too thick a web for a conventional re-grind.

Speeds and feeds for any type of metal cutting is a complex business.
Factors such as type of material to be cut, the type of drill, the kind of
steel in the drill, the design & condition of the drilling machine, the
shape & sharpness of the drill point and the coolant used.

http://snurl.com/278c or, to download (18Mb), http://snurl.com/278d

But if you follow earlier advice about pilot holes (lots of them
getting bigger in stages 'till you reach 13mm) you should get away with
this job.

Except that, by then, the final hole may have wandered a little from
where you'd like it to be.

The cutting point of a twist drill is meant to be the "chisel edge"; by
drilling a pilot hole, you're making the drill cut on the flutes rather
than the chisel edge and therefore the drill will faithfully follow the
pilot hole. However, as the smaller drill is thinner, it is also more
flexible and may have deformed or deflected as it was fed into the work-
piece. Yes, it's a lot easier to drill one or more pilot holes, but it
may not be as accurate as drilling with the "right" size of drill.

But then, if one really wanted accuracy, one would drill slightly
undersize and then ream out the hole to the final diameter...

--
Paul

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.

"Dave" wrote in message
...
Hiya

I have just tried drilling some 3mm thick mild steel with a 13mm
hole......... hell of a lot of noise, loads of vibration and now the drill
seems to do anything but drill!

Ok, please stop laughing, I'm a beginer!!

The drill bit was a Piranna 'Bullet' that it said was for drilling metal,
but what I have only just realsied is that the max recomended rpm for 10mm
was about 1000. The drill was the cheapest Clarkes one speed drill (i'm on
a
budget and this might be a '1 of' project) so I guess this is much faster.

So my questions a
Is the drill running too fast? What speed should i drill 12mm holes at?
Does
anyone know where I can the cheapest drill to drill at the recommended
speed?

Thanks for any help given

Dave