I have a front door which has an elaborate cast iron/wrought iron frame.
I really don't know which! It looks a bit like this
http://www.p-wholesale.com/upimg/21/...new043-392.jpg

I need to drill into it and screw in a small screw - something like M3
or M4. I did manage to make a small pilot hole with an HSS drill, and I
am fairly hopeful that I can enlarge that. Before doing so, I want to
make sure that I can find a suitable tap for the M3 or M4 screw.

I tried Screwfix, and they sell whole sets for quite a lot of money, and
none of them have good reviews. I just need one, so can anyone advise me
what to get, please? And where?

In article ,
GB wrote:
I tried Screwfix, and they sell whole sets for quite a lot of money, and
none of them have good reviews. I just need one, so can anyone advise me
what to get, please? And where?

A good tool shop or engineering supplier. Of course you may not have one
within reach. And they can be very expensive. Ebay is probably the easy
option. Look for a known brand like Dormer.

--
*I went to school to become a wit, only got halfway through.

Dave Plowman London SW
To e-mail, change noise into sound.

On Wednesday, September 5, 2012 2:39:43 PM UTC+1, GB wrote:
I have a front door which has an elaborate cast iron/wrought iron frame.
I really don't know which! It looks a bit like this
http://www.p-wholesale.com/upimg/21/...ew043-392..jpg


I need to drill into it and screw in a small screw - something like M3
or M4. I did manage to make a small pilot hole with an HSS drill, and I
am fairly hopeful that I can enlarge that. Before doing so, I want to
make sure that I can find a suitable tap for the M3 or M4 screw.


I tried Screwfix, and they sell whole sets for quite a lot of money, and
none of them have good reviews. I just need one, so can anyone advise me
what to get, please? And where?

It's most probably mild steel unless it's quite old, in which case it *could* be wrought iron - but I'd not treat those very differently. It's unlikely to be cast iron, I'd say.

There are plenty of online suppliers if you don't have a good tool shop near you, or you could try eBay - e.g. http://www.ebay.co.uk/itm/HSS-M3-METRIC-HAND-TAP-SET-3PCS-3-0MM-X-0-5MM-/250453022361?pt=UK_Home_Garden_PowerTools_SM&hash= item3a5029d699
You'd probably be looking to pay around £3 for an HSS tap (I wouldn't go for carbon steel) or maybe £5-6 for a set of three, plus around a fiver for a tap wrench. As long as you're tapping a through hole or one drilled significantly deeper than the screw you can probably get away with just a taper or second tap. (The traditional way is to start tapping using a taper tap, then when this has reached near the bottom of the hole do the same with the second and then the plug or bottoming tap)
You can buy special lubricants for tapping, but for a one-off you could probably get away with 3-in1 or similar. I wouldn't try to tap mild steel or wrought iron without lubricant.
Finally, remember that taps are quite brittle and an absolute PITA to remove if you break them in the hole, so take things steadily, make sure you start the tap straight, and don't try to take the tap hard down to the bottom of the hole (that part is much easier if you can arrange for it to be a through hole!)
If you can use an M4 rather than M3 tap it probably will be a little stronger.
Good luck!

On 05/09/2012 14:39, GB wrote:
I have a front door which has an elaborate cast iron/wrought iron frame.
I really don't know which! It looks a bit like this
http://www.p-wholesale.com/upimg/21/...new043-392.jpg


I need to drill into it and screw in a small screw - something like M3
or M4. I did manage to make a small pilot hole with an HSS drill, and I
am fairly hopeful that I can enlarge that. Before doing so, I want to
make sure that I can find a suitable tap for the M3 or M4 screw.

I tried Screwfix, and they sell whole sets for quite a lot of money, and
none of them have good reviews. I just need one, so can anyone advise me
what to get, please? And where?

Would a self-tapping screw do the job?

On 05/09/2012 16:04, wrote:
On Wednesday, September 5, 2012 2:39:43 PM UTC+1, GB wrote:
I have a front door which has an elaborate cast iron/wrought iron frame.
I really don't know which! It looks a bit like this
http://www.p-wholesale.com/upimg/21/...ew043-392..jpg


I need to drill into it and screw in a small screw - something like M3
or M4. I did manage to make a small pilot hole with an HSS drill, and I
am fairly hopeful that I can enlarge that. Before doing so, I want to
make sure that I can find a suitable tap for the M3 or M4 screw.


I tried Screwfix, and they sell whole sets for quite a lot of money, and
none of them have good reviews. I just need one, so can anyone advise me
what to get, please? And where?

It's most probably mild steel unless it's quite old, in which case it *could* be wrought iron - but I'd not treat those very differently. It's unlikely to be cast iron, I'd say.

There are plenty of online suppliers if you don't have a good tool shop near you, or you could try eBay - e.g. http://www.ebay.co.uk/itm/HSS-M3-METRIC-HAND-TAP-SET-3PCS-3-0MM-X-0-5MM-/250453022361?pt=UK_Home_Garden_PowerTools_SM&hash= item3a5029d699
You'd probably be looking to pay around £3 for an HSS tap (I wouldn't go for carbon steel) or maybe £5-6 for a set of three, plus around a fiver for a tap wrench. As long as you're tapping a through hole or one drilled significantly deeper than the screw you can probably get away with just a taper or second tap. (The traditional way is to start tapping using a taper tap, then when this has reached near the bottom of the hole do the same with the second and then the plug or bottoming tap)
You can buy special lubricants for tapping, but for a one-off you could probably get away with 3-in1 or similar. I wouldn't try to tap mild steel or wrought iron without lubricant.
Finally, remember that taps are quite brittle and an absolute PITA to remove if you break them in the hole, so take things steadily, make sure you start the tap straight, and don't try to take the tap hard down to the bottom of the hole (that part is much easier if you can arrange for it to be a through hole!)
If you can use an M4 rather than M3 tap it probably will be a little stronger.
Good luck!


Thanks so much! I think that that answers all my questions, including
the ones I have no asked! (I was all set to ask what the difference is
between a taper, plug and bottoming tap.) It does need to be a blind
hole, so I'll need all three.

On 05/09/2012 16:05, Andrew May wrote:
On 05/09/2012 14:39, GB wrote:
I have a front door which has an elaborate cast iron/wrought iron frame.
I really don't know which! It looks a bit like this
http://www.p-wholesale.com/upimg/21/...new043-392.jpg



I need to drill into it and screw in a small screw - something like M3
or M4. I did manage to make a small pilot hole with an HSS drill, and I
am fairly hopeful that I can enlarge that. Before doing so, I want to
make sure that I can find a suitable tap for the M3 or M4 screw.

I tried Screwfix, and they sell whole sets for quite a lot of money, and
none of them have good reviews. I just need one, so can anyone advise me
what to get, please? And where?

Would a self-tapping screw do the job?

It will need to be undone and done up again from time to time, so it's
probably better to do it right from day one. Thanks

In article ,
Andrew May wrote:
On 05/09/2012 14:39, GB wrote:
I have a front door which has an elaborate cast iron/wrought iron
frame. I really don't know which! It looks a bit like this
http://www.p-wholesale.com/upimg/21/...new043-392.jpg


I need to drill into it and screw in a small screw - something like M3
or M4. I did manage to make a small pilot hole with an HSS drill, and
I am fairly hopeful that I can enlarge that. Before doing so, I want
to make sure that I can find a suitable tap for the M3 or M4 screw.

I tried Screwfix, and they sell whole sets for quite a lot of money,
and none of them have good reviews. I just need one, so can anyone
advise me what to get, please? And where?

Would a self-tapping screw do the job?

On my old Rover, there are some self tapping bolts with a fine thread and
flutes down them that go into mild steel plates. No idea what they're
called or where you'd find them. The smallest are 1/4" diameter.

--
*Some days you're the dog, some days the hydrant.

Dave Plowman London SW
To e-mail, change noise into sound.

On Wed, 05 Sep 2012 16:56:20 +0100, "Dave Plowman (News)"
wrote:

In article ,
Andrew May wrote:
On 05/09/2012 14:39, GB wrote:
I have a front door which has an elaborate cast iron/wrought iron
frame. I really don't know which! It looks a bit like this
http://www.p-wholesale.com/upimg/21/...new043-392.jpg


I need to drill into it and screw in a small screw - something like M3
or M4. I did manage to make a small pilot hole with an HSS drill, and
I am fairly hopeful that I can enlarge that. Before doing so, I want
to make sure that I can find a suitable tap for the M3 or M4 screw.

I tried Screwfix, and they sell whole sets for quite a lot of money,
and none of them have good reviews. I just need one, so can anyone
advise me what to get, please? And where?

Would a self-tapping screw do the job?

On my old Rover, there are some self tapping bolts with a fine thread and
flutes down them that go into mild steel plates. No idea what they're
called or where you'd find them. The smallest are 1/4" diameter.

Taptite. They are available in much smaller sizes too

Ignore the photo on the link below as it isn't correct. They are properly
threaded using standard metric threads and produce perfectly usable female
thread forms in a wide range of substrates.

http://www.comdir.co.uk/Products.asp...HeadPoziDrive/

(no connection etc)


--

GB wrote:
I have a front door which has an elaborate cast iron/wrought iron
frame. I really don't know which! It looks a bit like this
http://www.p-wholesale.com/upimg/21/...new043-392.jpg

I need to drill into it and screw in a small screw - something like M3
or M4. I did manage to make a small pilot hole with an HSS drill, and
I am fairly hopeful that I can enlarge that. Before doing so, I want
to make sure that I can find a suitable tap for the M3 or M4 screw.

I tried Screwfix, and they sell whole sets for quite a lot of money,
and none of them have good reviews. I just need one, so can anyone
advise me what to get, please? And where?

MSC Industrial supply which used to be J&L.

www.mscdirect.co.uk/

Page 164. Metric HSS taps for about £4 each. Don't buy carbon steel,
especially in small sizes. They snap like carrots. You won't need a
bottoming tap (taper tap) for an easy cutting material like cast iron so a
second (plug) tap will do most jobs with a bottoming only needed for blind
holes. Cast iron taps best dry so no lubricant.
--
Dave Baker

Andrew May wrote:
On 05/09/2012 14:39, GB wrote:
I have a front door which has an elaborate cast iron/wrought iron frame.
I really don't know which! It looks a bit like this
http://www.p-wholesale.com/upimg/21/...new043-392.jpg



I need to drill into it and screw in a small screw - something like M3
or M4. I did manage to make a small pilot hole with an HSS drill, and I
am fairly hopeful that I can enlarge that. Before doing so, I want to
make sure that I can find a suitable tap for the M3 or M4 screw.

I tried Screwfix, and they sell whole sets for quite a lot of money, and
none of them have good reviews. I just need one, so can anyone advise me
what to get, please? And where?

Would a self-tapping screw do the job?

very dodgy into cast iron.


--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

The Other Mike wrote:
On Wed, 05 Sep 2012 16:56:20 +0100, "Dave Plowman (News)"
wrote:

In article ,
Andrew May wrote:
On 05/09/2012 14:39, GB wrote:
I have a front door which has an elaborate cast iron/wrought iron
frame. I really don't know which! It looks a bit like this
http://www.p-wholesale.com/upimg/21/...new043-392.jpg


I need to drill into it and screw in a small screw - something like M3
or M4. I did manage to make a small pilot hole with an HSS drill, and
I am fairly hopeful that I can enlarge that. Before doing so, I want
to make sure that I can find a suitable tap for the M3 or M4 screw.

I tried Screwfix, and they sell whole sets for quite a lot of money,
and none of them have good reviews. I just need one, so can anyone
advise me what to get, please? And where?

Would a self-tapping screw do the job?
On my old Rover, there are some self tapping bolts with a fine thread and
flutes down them that go into mild steel plates. No idea what they're
called or where you'd find them. The smallest are 1/4" diameter.

Taptite. They are available in much smaller sizes too

Ignore the photo on the link below as it isn't correct. They are properly
threaded using standard metric threads and produce perfectly usable female
thread forms in a wide range of substrates.

Of which cast iron is not one.

http://www.comdir.co.uk/Products.asp...HeadPoziDrive/

(no connection etc)




--
Ineptocracy

(in-ep-toc-ra-cy) €“ a system of government where the least capable to
lead are elected by the least capable of producing, and where the
members of society least likely to sustain themselves or succeed, are
rewarded with goods and services paid for by the confiscated wealth of a
diminishing number of producers.

On Wednesday, September 5, 2012 6:18:12 PM UTC+1, Dave Baker wrote:
snip
Page 164. Metric HSS taps for about £4 each. Don't buy carbon steel,
especially in small sizes. They snap like carrots. You won't need a
bottoming tap (taper tap) for an easy cutting material like cast iron so a
second (plug) tap will do most jobs with a bottoming only needed for blind
holes. Cast iron taps best dry so no lubricant.

We seem to have come to opposite conclusions about whether this is cast iron - I looked at the picture and reckoned that most of it would be mild steel unless it was old enouh to have been made out of wrought iron. I'm not sure what's the best test to suggest to the OP to confirm - for me I'd probably decide by the behaviour when drilling, as cast iron will produce small chips where mild steel would tend to produce spirals or helices of swarf, but for someone who has possibly not dealt with either it would be more difficult.

On Sep 5, 5:46*pm, The Other Mike
wrote:
On my old Rover, there are some self tapping bolts with a fine thread and
flutes down them that go into mild steel plates. No idea what they're
called or where you'd find them. The smallest are 1/4" diameter.

Taptite. *They are available in much smaller sizes too

No, Taptite are for aluminium. They have a non-circular section, but
no flutes, so they work by deforming a thread rather than cutting it.
It's a bitlike a rolled thread, but internal. They work very well
(especially on copper, which is otherwise a sod to tap), but only on
ductile materials.

On Sep 5, 2:39*pm, GB wrote:
I need to drill into it and screw in a small screw - something like M3
or M4.

If it's mild steel or a high quality cast iron casting, then you can
buy a cheap set of carbon steel taps (all sizes). However this will
probably be a set of just one tap for each size, approximately a
second. So they'll tap through holes, but not blind holes. (If
you're stuck, tap once, grind the taper off, then tap to the bottom
again).

Carbon steel taps don't work on alloy steels, cheap cast iron or
wrought iron (unless it's swords). Then you need to use HSS taps.
These are a bit too expensive to buy a whole set, but they are worth
buying as a pair: second and plug, of a useful size like M4 (or more
useful M6). Taper (the first) taps are only usable in through holes,
useful for experienced tappers, and only necessary in hard metals.
Otherwise it's easier to just start with the second tap.

I wouldn't use anything smaller than M5 for this type of work, unless
essential.

"GB" wrote in message
...
I have a front door which has an elaborate cast iron/wrought iron frame. I
really don't know which! It looks a bit like this
http://www.p-wholesale.com/upimg/21/...new043-392.jpg

I need to drill into it and screw in a small screw - something like M3 or
M4. I did manage to make a small pilot hole with an HSS drill, and I am
fairly hopeful that I can enlarge that. Before doing so, I want to make
sure that I can find a suitable tap for the M3 or M4 screw.

I tried Screwfix, and they sell whole sets for quite a lot of money, and
none of them have good reviews. I just need one, so can anyone advise me
what to get, please? And where?


Whatever tap(s) you use, NEVER drive the tap in until it's too hard to get
it any farther,
Take no more than one or two turns of the tap at a time, removing the tap
completely and cleaning it (and blowing the hole out with an air gun if you
have one) between each go. That way you're unlikely ever to suffer the
disaster of a sheared tap.