At some point in the next week or two, I'll want to drill and tap a
dozen holes into stainless steel tube, this is 2mm wall thickness, 42mm
diameter handrail, I'll have a 100-200mm offcut to practice on.

Now, we didn't do metalworking at school, so I'm lacking in the basics,
but a bit of searching seems to suggest ...

For M5 bolts, use a 4.2mm drill, assuming it's 0.8mm course pitch (need
to check) hopefully an 18V cordless drill/driver isn't going to struggle?

Drill slowly to avoid work-hardening

Lubricate (use WD40 at a push)

As I'm tapping through, rather than into, the steel use a spiral point,
rather than spiral flute, tap.

What flavour of HSS (cobalt, vanadium, extra vanadium, nitride/oxide
coating etc) does the tap need to be to cope with 304 stainless?

I see 1/4" hex shank taps are available, e.g.
http://uk.rs-online.com/web/p/threading-taps/6699384

Will these work OK in the drill/driver? Or should I hand tap?

Given I'm unlikely to ever want/need a full tap/die set, can you buy
screwdriver or T-handle style single taps?

Any other tips appreciated.

Andy Burns wrote:
At some point in the next week or two, I'll want to drill and tap a
dozen holes into stainless steel tube, this is 2mm wall thickness, 42mm
diameter handrail, I'll have a 100-200mm offcut to practice on.

Now, we didn't do metalworking at school,
No, I wasn't allowed to because I was GCE material so metalwork would
have been 'wasting my time'.

so I'm lacking in the basics,
but a bit of searching seems to suggest ...

For M5 bolts, use a 4.2mm drill, assuming it's 0.8mm course pitch (need
to check)
Are you sure that's right?

hopefully an 18V cordless drill/driver isn't going to struggle?
Take it very steady.

Drill slowly to avoid work-hardening

Lubricate (use WD40 at a push)

As I'm tapping through, rather than into, the steel use a spiral point,
rather than spiral flute, tap.

What flavour of HSS (cobalt, vanadium, extra vanadium, nitride/oxide
coating etc) does the tap need to be to cope with 304 stainless?

I see 1/4" hex shank taps are available, e.g.
http://uk.rs-online.com/web/p/threading-taps/6699384

Will these work OK in the drill/driver? Or should I hand tap?
Oh God, hand tap! It will be a total ****-up otherwise. It's a bit of an
art. Practice first.
Buy the tap that only makes a shallow thread, use that first, then the
normal one.


Given I'm unlikely to ever want/need a full tap/die set, can you buy
screwdriver or T-handle style single taps?
No use the crossbar type. You have to put quite a lot of force into it.
But you also have to have a precise and careful touch.

Any other tips appreciated.
Don't do it!

Bill

On 21/09/2013 19:51, Andy Burns wrote:
At some point in the next week or two, I'll want to drill and tap a
dozen holes into stainless steel tube, this is 2mm wall thickness, 42mm
diameter handrail, I'll have a 100-200mm offcut to practice on.

Now, we didn't do metalworking at school, so I'm lacking in the basics,
but a bit of searching seems to suggest ...

For M5 bolts, use a 4.2mm drill, assuming it's 0.8mm course pitch (need
to check) hopefully an 18V cordless drill/driver isn't going to struggle?

Drill slowly to avoid work-hardening

Lubricate (use WD40 at a push)

As I'm tapping through, rather than into, the steel use a spiral point,
rather than spiral flute, tap.

What flavour of HSS (cobalt, vanadium, extra vanadium, nitride/oxide
coating etc) does the tap need to be to cope with 304 stainless?

I see 1/4" hex shank taps are available, e.g.
http://uk.rs-online.com/web/p/threading-taps/6699384

Will these work OK in the drill/driver? Or should I hand tap?

Given I'm unlikely to ever want/need a full tap/die set, can you buy
screwdriver or T-handle style single taps?

Any other tips appreciated.


To drill stainless steel, use a slow speed drill, and don't put too much
pressure on the drill. Also, I strongly recommend you use proper metal
cutting fluid or paste.

You said you were going to tap the drilled holes, so make sure you use
the correct sized drill bit for the tap size.You can do a search for that.
Well I've done it for you:
http://www.engineershandbook.com/Tab...ictapdrill.htm

I have only had about 30 odd years experience in the engineering trade,
so I know nothing, lol.

Good luck

Bill Wright wrote:

Andy Burns wrote:

we didn't do metalworking at school,

No, I wasn't allowed to because I was GCE material so metalwork would
have been 'wasting my time'.

Round our way, Grammar school did woodwork, secondary modern did metalwork.

For M5 bolts, use a 4.2mm drill

Are you sure that's right?

No, but it's *an* answer I found, happy to be told different.

Take it very steady.
hand tap! It will be a total ****-up otherwise. It's a bit of an
art. Practice first.

Yes, I suspect my short offcut will look rather bullet-ridden before I
try the real holes.

Buy the tap that only makes a shallow thread, use that first, then the
normal one.

Do they have proper names?

use the crossbar type. You have to put quite a lot of force into it.
But you also have to have a precise and careful touch.

OK

Don't do it!

That is an option if I **** up all my test holes, metal bashing is my
neighbour's original trade.

Bob H wrote:

To drill stainless steel, use a slow speed drill, and don't put too much
pressure on the drill. Also, I strongly recommend you use proper metal
cutting fluid or paste.

Good enough?
http://www.cromwell.co.uk/SHR7324000K

make sure you use the correct sized drill bit for the tap size.
http://www.engineershandbook.com/Tab...ictapdrill.htm

Thanks, that confirms the 4.2mm drill for M5x0.8

I have only had about 30 odd years experience in the engineering trade,
so I know nothing, lol.

:-)

Bob H wrote:

To drill stainless steel, use a slow speed drill, and don't put too much
pressure on the drill. Also, I strongly recommend you use proper metal
cutting fluid or paste.

I've just remembered somewhere with a substantial pillar drill I can
probably talk my way into using ...

On 21/09/2013 20:27, Andy Burns wrote:
Bob H wrote:

To drill stainless steel, use a slow speed drill, and don't put too much
pressure on the drill. Also, I strongly recommend you use proper metal
cutting fluid or paste.

Good enough?
http://www.cromwell.co.uk/SHR7324000K

Yes that will do just fine. Give the drill bit plenty of it when its
cutting.

make sure you use the correct sized drill bit for the tap size.
http://www.engineershandbook.com/Tab...ictapdrill.htm

Thanks, that confirms the 4.2mm drill for M5x0.8

I have only had about 30 odd years experience in the engineering trade,
so I know nothing, lol.

:-)

On Sat, 21 Sep 2013 20:07:49 +0100, Bill Wright
wrote:

No, I wasn't allowed to because I was GCE material so metalwork would
have been 'wasting my time'.

Ah. You had that one as well. (

Bob H wrote:
On 21/09/2013 19:51, Andy Burns wrote:
At some point in the next week or two, I'll want to drill and tap a
dozen holes into stainless steel tube, this is 2mm wall thickness,
42mm diameter handrail, I'll have a 100-200mm offcut to practice on.

Now, we didn't do metalworking at school, so I'm lacking in the
basics, but a bit of searching seems to suggest ...

For M5 bolts, use a 4.2mm drill, assuming it's 0.8mm course pitch
(need to check) hopefully an 18V cordless drill/driver isn't going
to struggle? Drill slowly to avoid work-hardening

Lubricate (use WD40 at a push)

As I'm tapping through, rather than into, the steel use a spiral
point, rather than spiral flute, tap.

What flavour of HSS (cobalt, vanadium, extra vanadium, nitride/oxide
coating etc) does the tap need to be to cope with 304 stainless?

I see 1/4" hex shank taps are available, e.g.
http://uk.rs-online.com/web/p/threading-taps/6699384

Will these work OK in the drill/driver? Or should I hand tap?

Given I'm unlikely to ever want/need a full tap/die set, can you buy
screwdriver or T-handle style single taps?

Any other tips appreciated.


To drill stainless steel, use a slow speed drill, and don't put too
much pressure on the drill. Also, I strongly recommend you use proper
metal cutting fluid or paste.

You said you were going to tap the drilled holes, so make sure you use
the correct sized drill bit for the tap size.You can do a search for
that. Well I've done it for you:
http://www.engineershandbook.com/Tab...ictapdrill.htm

I have only had about 30 odd years experience in the engineering
trade, so I know nothing, lol.

Good luck

Taps come in setrs of three - taper, second cut and final cut.
use them in that order in a hand tap wrench, and do it very slowly,
in a series of small cuts - one or two turns cutting followed by a few
turns in reverse to clear the swarf from the flutes of the tap.
Lubricate with white spirit.

Jim Hawkins

In article , Jim Hawkins
writes
Bob H wrote:

To drill stainless steel, use a slow speed drill, and don't put too
much pressure on the drill. Also, I strongly recommend you use proper
metal cutting fluid or paste.

You said you were going to tap the drilled holes, so make sure you use
the correct sized drill bit for the tap size.You can do a search for
that. Well I've done it for you:
http://www.engineershandbook.com/Tab...ictapdrill.htm

I have only had about 30 odd years experience in the engineering
trade, so I know nothing, lol.

Good luck

Taps come in setrs of three - taper, second cut and final cut.
use them in that order in a hand tap wrench, and do it very slowly,
in a series of small cuts - one or two turns cutting followed by a few
turns in reverse to clear the swarf from the flutes of the tap.
Lubricate with white spirit.

Whilst true for a blind hole there is no need to run anything but a
taper for 2mm material with plenty of clearance behind.

I'd be a lot more worried about using cheese type HSS taps in stainless
for a bottom hole but I would certainly have a go with one on thin
material. For this I would view excess force as a warning of impending
breakage and an invitation to back off (breaking the swarf) before
resuming.

With cobalt drills being so reasonably priced these days I would buy 2
or 3 for the job, just in case, they will make it sooo much easier, they
really are a joy to use but more brittle. No need for a pilot at that
diameter but an automatic (or manual) centre punch will make centring
easier.
--
fred
it's a ba-na-na . . . .

fred wrote:

there is no need to run anything but a
taper for 2mm material with plenty of clearance behind.

Thanks, makes sense

I'd be a lot more worried about using cheese type HSS taps in stainless
for a bottom hole but I would certainly have a go with one on thin
material.

I find it odd that they only specify suitability for "some" stainless
steel, without saying which

http://www.cromwell.co.uk/SHR0850330A

I presume 304 is less hard than 316?

With cobalt drills being so reasonably priced these days I would buy 2
or 3 for the job, just in case, they will make it sooo much easier

Yes, I always bargain on a having couple of spares for small diameters,
had already put some cobalt ones in the basket.

In article ,
Andy Burns wrote:
At some point in the next week or two, I'll want to drill and tap a
dozen holes into stainless steel tube, this is 2mm wall thickness, 42mm
diameter handrail, I'll have a 100-200mm offcut to practice on.

Now, we didn't do metalworking at school, so I'm lacking in the basics,
but a bit of searching seems to suggest ...

For M5 bolts, use a 4.2mm drill, assuming it's 0.8mm course pitch (need
to check) hopefully an 18V cordless drill/driver isn't going to struggle?

A 2mm wall thickness ain't going to give much of a thread for M5 bolts.
The usual way would be to weld in bosses to increase the thickness. As a
rule of thumb, you want about the same thread length as the diameter as a
minumum.

--
*If you can't see my mirrors, I'm doing my hair*

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

On 21/09/2013 20:17, Andy Burns wrote:

Round our way, Grammar school did woodwork, secondary modern did metalwork.


The Grammar school I went to did both, but only until the 3rd year, then
if you wanted to continue with metalwork you had to do Technical Drawing
which I disliked somewhat Ok, disliked a lot, I ended up doing
maths/chem/phys/bio instead

Dave Plowman (News) wrote:

A 2mm wall thickness ain't going to give much of a thread for M5 bolts.

It's what's specified by the manufacturer of the tube and brackets,
nonetheless.

The usual way would be to weld in bosses to increase the thickness. As a
rule of thumb, you want about the same thread length as the diameter as a
minumum.

The balluster posts are available pre-cut/drilled to take the glass
clamps, so I've purchased those, which are M8 tapped, I don't think they
use thread inserts for them.

On Sat, 21 Sep 2013 19:51:15 +0100 Andy Burns wrote :
At some point in the next week or two, I'll want to drill and tap a
dozen holes into stainless steel tube, this is 2mm wall thickness,
42mm diameter handrail, I'll have a 100-200mm offcut to practice on.

Would threaded pop rivets be suitable? e.g.
http://www.poprivet.co.uk/productran...t=m5fro_s_s_39

--
Tony Bryer, Greentram: 'Software to build on',
Melbourne, Australia www.greentram.com

Dave Plowman (News) wrote:

A 2mm wall thickness ain't going to give much of a thread for M5 bolts.
The usual way would be to weld in bosses to increase the thickness.

If you thought Apple were the masters of the "some sequences shortened"
video, try this

http://youtu.be/dKeoFqSddaI?t=49s

As a rule of thumb, you want about the same thread length as the
diameter as a minumum.

Contrary to my earier reply, they do seem to use an insert on the M8
bolts, I'll check when they arrive, if they use them in the pre-made
posts, then rivnuts may be the way to go for the M5 holes.

http://youtu.be/yZxyucLqXCA?t=10s

Tony Bryer wrote:

On Sat, 21 Sep 2013 19:51:15 +0100 Andy Burns wrote :

I'll want to drill and tap a dozen holes into stainless steel tube,
this is 2mm wall thickness, 42mm diameter handrail

Would threaded pop rivets be suitable? e.g.
http://www.poprivet.co.uk/productran...t=m5fro_s_s_39

Yes, just started considering that, the tool is as cheap as buying tap &
holder, and sounds an easier process.

Andy Burns wrote:
fred wrote:

there is no need to run anything but a
taper for 2mm material with plenty of clearance behind.

Thanks, makes sense

I'd be a lot more worried about using cheese type HSS taps in stainless
for a bottom hole but I would certainly have a go with one on thin
material.

I find it odd that they only specify suitability for "some" stainless
steel, without saying which

http://www.cromwell.co.uk/SHR0850330A

I presume 304 is less hard than 316?

With cobalt drills being so reasonably priced these days I would buy 2
or 3 for the job, just in case, they will make it sooo much easier

Yes, I always bargain on a having couple of spares for small diameters,
had already put some cobalt ones in the basket.


contrary to common opinion ordinary Stainless is not hard per se but it
is tough, it is softer than a lot of steels.

On 22/09/2013 04:56, Tony Bryer wrote:
On Sat, 21 Sep 2013 19:51:15 +0100 Andy Burns wrote :
At some point in the next week or two, I'll want to drill and tap a
dozen holes into stainless steel tube, this is 2mm wall thickness,
42mm diameter handrail, I'll have a 100-200mm offcut to practice on.

Would threaded pop rivets be suitable? e.g.
http://www.poprivet.co.uk/productran...t=m5fro_s_s_39


Taptite screws would be better IMO.
They are shaped to roll a thread into thin sheets as you screw them in.
they don't cut the metal like self tapers do.

"Andy Burns" wrote in message
...
At some point in the next week or two, I'll want to drill and tap a dozen
holes into stainless steel tube, this is 2mm wall thickness, 42mm diameter
handrail, I'll have a 100-200mm offcut to practice on.

Now, we didn't do metalworking at school, so I'm lacking in the basics,
but a bit of searching seems to suggest ...

For M5 bolts, use a 4.2mm drill, assuming it's 0.8mm course pitch (need to
check) hopefully an 18V cordless drill/driver isn't going to struggle?

Drill slowly to avoid work-hardening

Lubricate (use WD40 at a push)

As I'm tapping through, rather than into, the steel use a spiral point,
rather than spiral flute, tap.

What flavour of HSS (cobalt, vanadium, extra vanadium, nitride/oxide
coating etc) does the tap need to be to cope with 304 stainless?

I see 1/4" hex shank taps are available, e.g.
http://uk.rs-online.com/web/p/threading-taps/6699384

Will these work OK in the drill/driver? Or should I hand tap?

Given I'm unlikely to ever want/need a full tap/die set, can you buy
screwdriver or T-handle style single taps?

Any other tips appreciated.

It's not practical to tap metal only 2mm thick for an M5 screw.
SS is a bugger to anything with, esp.tapping threads.

Welding job really by someone who is good at it.

You might be able to drill a clearance hole and fish a bolt down the pipe
and out of the hole.

harryagain wrote:

"Andy Burns" wrote:

drill and tap a dozen
holes into stainless steel tube, this is 2mm wall thickness, 42mm diameter
handrail

It's not practical to tap metal only 2mm thick for an M5 screw.
SS is a bugger to anything with, esp.tapping threads.

Even though it *is* what is recommended by the manufacturer (they only
use rivnuts or flowdrilling for M6 and M8 holes and the brackets require
M5) I've taken on-board the difficulties of tapping, and have ordered
some A2 M5 rivnuts and a setting tool - plenty to practice with.

On 21/09/2013 19:51, Andy Burns wrote:
At some point in the next week or two, I'll want to drill and tap a
dozen holes into stainless steel tube, this is 2mm wall thickness, 42mm
diameter handrail, I'll have a 100-200mm offcut to practice on.


Any other tips appreciated.


2mm is not very thick for a thread, but stainless is quite soft ...
drill with lubricant, white spirit will do if you don't have proper
cutting fluid.

Use a taper tap first, keep it 100% vertical ... don't waggle it about,
moderate pressure, screw it in gently ... it will start to bite .. then
1/2 turn fwd, followed by 1/4 turn back, and keep going until through.

Then put through the 2nd tap (or plug) depends which you have.

"Andy Burns" wrote in message
o.uk...
harryagain wrote:

"Andy Burns" wrote:

drill and tap a dozen
holes into stainless steel tube, this is 2mm wall thickness, 42mm
diameter
handrail

It's not practical to tap metal only 2mm thick for an M5 screw.
SS is a bugger to anything with, esp.tapping threads.

Even though it *is* what is recommended by the manufacturer (they only use
rivnuts or flowdrilling for M6 and M8 holes and the brackets require M5)
I've taken on-board the difficulties of tapping, and have ordered some A2
M5 rivnuts and a setting tool - plenty to practice with.


Well then that would work, no tapping required.
Be sure to make a good indent with a centre punch in the pipe before you
start to drill.
The drill tends to wander on SS, esp. on a convex surface.
I don't think you will need practice, pretty straightforward.
Just lots of coolant. I find WD40 OK for this.

On 21/09/2013 20:38, Andy Burns wrote:
Bob H wrote:

To drill stainless steel, use a slow speed drill, and don't put too much
pressure on the drill. Also, I strongly recommend you use proper metal
cutting fluid or paste.

I've just remembered somewhere with a substantial pillar drill I can
probably talk my way into using ...


Yes you *definitely* need a pillar drill, and a good centre punch mark
to start. And clamp the pipe securely, ideally in a proper machine vice.
Wrap with cardboard to prevent marking.

Low speed, but IME quite high pressure. And a sharp drill.

See if you can find someone with a tin of trefolex cutting compound,
ideally for the drilling but especially for the tapping. And definitely
tap by hand, with frequent reversals (each time it starts to tighten
significantly) to clear swarf.

On 21/09/2013 23:47, Dave Plowman (News) wrote:
In article ,
Andy Burns wrote:
At some point in the next week or two, I'll want to drill and tap a
dozen holes into stainless steel tube, this is 2mm wall thickness, 42mm
diameter handrail, I'll have a 100-200mm offcut to practice on.

Now, we didn't do metalworking at school, so I'm lacking in the basics,
but a bit of searching seems to suggest ...

For M5 bolts, use a 4.2mm drill, assuming it's 0.8mm course pitch (need
to check) hopefully an 18V cordless drill/driver isn't going to struggle?

A 2mm wall thickness ain't going to give much of a thread for M5 bolts.
The usual way would be to weld in bosses to increase the thickness. As a
rule of thumb, you want about the same thread length as the diameter as a
minumum.


Good point. Rivnuts are another good option.

newshound wrote:

Andy Burns wrote:

we didn't do metalworking at school

Rivnuts are another good option.

Thanks all for the education ...

The parts should arrive this week, I'll have to cut the (5 metre) tube
into the banister and balustrade lengths, mark it, then take it for a
quick trip up the motorway to use the pillar drill.

In article ,
Andy Burns wrote:
Even though it *is* what is recommended by the manufacturer (they only
use rivnuts or flowdrilling for M6 and M8 holes and the brackets require
M5) I've taken on-board the difficulties of tapping, and have ordered
some A2 M5 rivnuts and a setting tool - plenty to practice with.

I've got one of those kits and it's very useful. Not tried it in tube,
though. They're really designed for a flat surface.

--
*Errors have been made. Others will be blamed.

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

Dave Plowman (News) wrote:

Andy Burns wrote:

have ordered some A2 M5 rivnuts and a setting tool

I've got one of those kits and it's very useful. Not tried it in tube,
though. They're really designed for a flat surface.

I've bought some with countersunk heads

http://www.ebay.co.uk/itm/251202027233
http://i726.photobucket.com/albums/w...CSKheaddia.jpg

and some flat head ones

http://www.ebay.co.uk/itm/310543511992
http://i726.photobucket.com/albums/w...NUTDIAGRAM.jpg

Hoping the countersunk ones will work best, the internal deformed
portion will be what resists pulling-out, the reduced head will be less
good at resisting push-in, but that will be sandwiched between the
surrounding tube and the saddle-bracket, so should not be much of an issue.

I saw a suggestion that the flat ones could be peened over if necessary,
there are some inbetween small flat head ones too, but I didn't buy any
of those.

In article ,
Andy Burns wrote:
Dave Plowman (News) wrote:

Andy Burns wrote:

have ordered some A2 M5 rivnuts and a setting tool

I've got one of those kits and it's very useful. Not tried it in tube,
though. They're really designed for a flat surface.

I've bought some with countersunk heads

http://www.ebay.co.uk/itm/251202027233
http://i726.photobucket.com/albums/w...CSKheaddia.jpg

and some flat head ones

http://www.ebay.co.uk/itm/310543511992
http://i726.photobucket.com/albums/w...NUTDIAGRAM.jpg

Hoping the countersunk ones will work best, the internal deformed
portion will be what resists pulling-out, the reduced head will be less
good at resisting push-in, but that will be sandwiched between the
surrounding tube and the saddle-bracket, so should not be much of an
issue.

I saw a suggestion that the flat ones could be peened over if necessary,
there are some inbetween small flat head ones too, but I didn't buy any
of those.

I'm sure it will provide an adequate fixing. Just how good it will look -
if you can see it - will be the issue.

--
*Even a blind pig stumbles across an acorn now and again *

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

On 23/09/2013 06:29, harryagain wrote:
"Andy Burns" wrote in message
o.uk...
harryagain wrote:

"Andy Burns" wrote:

drill and tap a dozen
holes into stainless steel tube, this is 2mm wall thickness, 42mm
diameter
handrail

It's not practical to tap metal only 2mm thick for an M5 screw.
SS is a bugger to anything with, esp.tapping threads.

Even though it *is* what is recommended by the manufacturer (they only use
rivnuts or flowdrilling for M6 and M8 holes and the brackets require M5)
I've taken on-board the difficulties of tapping, and have ordered some A2
M5 rivnuts and a setting tool - plenty to practice with.


Well then that would work, no tapping required.
Be sure to make a good indent with a centre punch in the pipe before you
start to drill.
The drill tends to wander on SS, esp. on a convex surface.

It would be worth buying a centre drill for starting the holes...

http://www.ebay.co.uk/itm/RDGTOOLS-S...item43acd35fc6




--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article ,
John Rumm wrote:
Well then that would work, no tapping required. Be sure to make a good
indent with a centre punch in the pipe before you start to drill. The
drill tends to wander on SS, esp. on a convex surface.

It would be worth buying a centre drill for starting the holes...

http://www.ebay.co.uk/itm/RDGTOOLS-S...item43acd35fc6

I'm not sure how much use those are in a pillar drill - they're more
designed for use in a lathe. And tend to be made out of rather softer
steel than ordinary twist drills - so go blunt more quickly.

A decent centre punch should do the job - perhaps with a support down the
tube inside to avoid damage.

--
*Lottery: A tax on people who are bad at math.

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

On 23/09/2013 14:47, Dave Plowman (News) wrote:
In article ,
John Rumm wrote:
Well then that would work, no tapping required. Be sure to make a good
indent with a centre punch in the pipe before you start to drill. The
drill tends to wander on SS, esp. on a convex surface.

It would be worth buying a centre drill for starting the holes...

http://www.ebay.co.uk/itm/RDGTOOLS-S...item43acd35fc6

I'm not sure how much use those are in a pillar drill - they're more
designed for use in a lathe. And tend to be made out of rather softer
steel than ordinary twist drills - so go blunt more quickly.

IME they are ok as long as the quill is not too sloppy. Even then, if
you adjust the table so you don't need to use the drill at full depth
they usually give a marked improvement on the smaller twist drills.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

John Rumm wrote:

On 23/09/2013 14:47, Dave Plowman (News) wrote:

John Rumm wrote:

It would be worth buying a centre drill for starting the holes...
http://www.ebay.co.uk/itm/290662342598

I remember dad having a set of them, but those were rusted to hell 30
odd years ago.

I'm not sure how much use those are in a pillar drill - they're more
designed for use in a lathe. And tend to be made out of rather softer
steel than ordinary twist drills - so go blunt more quickly.

IME they are ok as long as the quill is not too sloppy. Even then, if
you adjust the table so you don't need to use the drill at full depth
they usually give a marked improvement on the smaller twist drills.

They don't seem to come in metric sizes (or at least not a full range),
so e.g. a 1/4" centre drill would only be useful as a pilot hole for a
7mm hole for the rivnut.

On 23/09/2013 18:28, Andy Burns wrote:
John Rumm wrote:

On 23/09/2013 14:47, Dave Plowman (News) wrote:

John Rumm wrote:

It would be worth buying a centre drill for starting the holes...
http://www.ebay.co.uk/itm/290662342598

I remember dad having a set of them, but those were rusted to hell 30
odd years ago.

I'm not sure how much use those are in a pillar drill - they're more
designed for use in a lathe. And tend to be made out of rather softer
steel than ordinary twist drills - so go blunt more quickly.

IME they are ok as long as the quill is not too sloppy. Even then, if
you adjust the table so you don't need to use the drill at full depth
they usually give a marked improvement on the smaller twist drills.

They don't seem to come in metric sizes (or at least not a full range),
so e.g. a 1/4" centre drill would only be useful as a pilot hole for a
7mm hole for the rivnut.


You only use a centre drill to make a "countersink", not to make a
through hole! I agree with John, they are fine in any reasonable pillar
drill.

newshound wrote:

You only use a centre drill to make a "countersink", not to make a
through hole! I agree with John, they are fine in any reasonable pillar
drill.

Oh OK, see I told you we didn't get taught it at school!

On Mon, 23 Sep 2013 14:12:12 +0100, John Rumm
wrote:

It would be worth buying a centre drill for starting the holes...

http://www.ebay.co.uk/itm/RDGTOOLS-S...item43acd35fc6

Split point drills will do a significantly better job and will only require one
operation.


--

On 23/09/2013 18:28, Andy Burns wrote:
John Rumm wrote:

On 23/09/2013 14:47, Dave Plowman (News) wrote:

John Rumm wrote:

It would be worth buying a centre drill for starting the holes...
http://www.ebay.co.uk/itm/290662342598

I remember dad having a set of them, but those were rusted to hell 30
odd years ago.

I'm not sure how much use those are in a pillar drill - they're more
designed for use in a lathe. And tend to be made out of rather softer
steel than ordinary twist drills - so go blunt more quickly.

IME they are ok as long as the quill is not too sloppy. Even then, if
you adjust the table so you don't need to use the drill at full depth
they usually give a marked improvement on the smaller twist drills.

They don't seem to come in metric sizes (or at least not a full range),
so e.g. a 1/4" centre drill would only be useful as a pilot hole for a
7mm hole for the rivnut.

The size is not that important - its just to get a hole started in the
right place. You don't have to drill that deep with them.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

In article ,
The Other Mike wrote:
On Mon, 23 Sep 2013 14:12:12 +0100, John Rumm
wrote:

It would be worth buying a centre drill for starting the holes...

http://www.ebay.co.uk/itm/RDGTOOLS-S...item43acd35fc6

Split point drills will do a significantly better job and will only
require one operation.

I was trying to remember what they were called.

--
*Nostalgia isn't what is used to be.

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

"John Rumm" wrote in message
o.uk...
On 23/09/2013 06:29, harryagain wrote:
"Andy Burns" wrote in message
o.uk...
harryagain wrote:

"Andy Burns" wrote:

drill and tap a dozen
holes into stainless steel tube, this is 2mm wall thickness, 42mm
diameter
handrail

It's not practical to tap metal only 2mm thick for an M5 screw.
SS is a bugger to anything with, esp.tapping threads.

Even though it *is* what is recommended by the manufacturer (they only
use
rivnuts or flowdrilling for M6 and M8 holes and the brackets require M5)
I've taken on-board the difficulties of tapping, and have ordered some
A2
M5 rivnuts and a setting tool - plenty to practice with.


Well then that would work, no tapping required.
Be sure to make a good indent with a centre punch in the pipe before you
start to drill.
The drill tends to wander on SS, esp. on a convex surface.

It would be worth buying a centre drill for starting the holes...

http://www.ebay.co.uk/itm/RDGTOOLS-S...item43acd35fc6



I think the main danger with thin SS is the drill gabbing and breaking as it
breaks through the metal.
You need not to be pressing too hard when you are almost through.

On Sat, 21 Sep 2013 20:17:21 +0100, Andy Burns
wrote:

Round our way, Grammar school did woodwork, secondary modern did metalwork.

Oddly, mine did both, in the interests of providing an all-round
education.