I need to cut two 40mm diameter holes in 5mm (I think) thick steel, it
may be a little thinner.

Will an ordinary hole cutter manage this? Any particular brands which
will survive better? Or is there a better tool?

I'm not too fussed if it takes quite a while and/or if the hole cutter
is worn out when finished.

--
Chris Green

On Mon, 8 Aug 2011 18:58:00 +0100, wrote:

I need to cut two 40mm diameter holes in 5mm (I think) thick steel, it
may be a little thinner.

Ring drill 5mm or so holes, junior hacksaw between the holes, half
round file?

--
Cheers
Dave.

wrote:
I need to cut two 40mm diameter holes in 5mm (I think) thick steel, it
may be a little thinner.

Will an ordinary hole cutter manage this? Any particular brands which
will survive better? Or is there a better tool?

I'm not too fussed if it takes quite a while and/or if the hole cutter
is worn out when finished.

http://www.screwfix.com/p/bosch-coba...saw-40mm/22748

or any of the 40mm holesaws from screwfix or anywhere else.

--
Adam

ARWadsworth wrote:
wrote:
I need to cut two 40mm diameter holes in 5mm (I think) thick steel,
it may be a little thinner.

Will an ordinary hole cutter manage this? Any particular brands
which will survive better? Or is there a better tool?

I'm not too fussed if it takes quite a while and/or if the hole
cutter is worn out when finished.

http://www.screwfix.com/p/bosch-coba...saw-40mm/22748

or any of the 40mm holesaws from screwfix or anywhere else.

Just to add to that, nothing blunts a holesaw faster than artex. I can add
lots of holes to a metal CU with a cutter, but one ceiling can bugger a
cutter up in minutes.

--
Adam

wrote:
I need to cut two 40mm diameter holes in 5mm (I think) thick steel, it
may be a little thinner.

Will an ordinary hole cutter manage this? Any particular brands which
will survive better? Or is there a better tool?

I'm not too fussed if it takes quite a while and/or if the hole cutter
is worn out when finished.

Do you mean a hole punch? I've not seen any that work with stainless over
3mm thick.

ARWadsworth pretended :
wrote:
I need to cut two 40mm diameter holes in 5mm (I think) thick steel, it
may be a little thinner.

Will an ordinary hole cutter manage this? Any particular brands which
will survive better? Or is there a better tool?

I'm not too fussed if it takes quite a while and/or if the hole cutter
is worn out when finished.

http://www.screwfix.com/p/bosch-coba...saw-40mm/22748

or any of the 40mm holesaws from screwfix or anywhere else.

Slow speed drill and lots of cutting paste to keep it cool.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk

In article ,
wrote:
I need to cut two 40mm diameter holes in 5mm (I think) thick steel, it
may be a little thinner.

Will an ordinary hole cutter manage this? Any particular brands which
will survive better? Or is there a better tool?

I'm not too fussed if it takes quite a while and/or if the hole cutter
is worn out when finished.

You might do better to find a local place with a water jet cutter.
Surprisingly cheap - assuming you can get the material to them.

A hole cutter will work - but use a very low speed and plenty cutting
fluid. And make sure you don't overheat it.

--
*Reality? Is that where the pizza delivery guy comes from?

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

wrote in message ...
I need to cut two 40mm diameter holes in 5mm (I think) thick steel, it
may be a little thinner.

Will an ordinary hole cutter manage this? Any particular brands which
will survive better? Or is there a better tool?

I'm not too fussed if it takes quite a while and/or if the hole cutter
is worn out when finished.

--
Chris Green
There are hole cutters and hole cutters. Some are only for wood.
You can get one for the job, they are not expensive. (Screwfix) It will need
to run pretty slow, a biggish drill (ideally a pillar drill or SD type
fitted with a chuck) and you need coolant on it, (water or oil ). If using
a hand drill, you can rock it as will then cut faster. Cooling is the
secret, without, it will overheat and go blunt in seconds.

harryagain wrote:

wrote in message ...
I need to cut two 40mm diameter holes in 5mm (I think) thick steel, it
may be a little thinner.

Will an ordinary hole cutter manage this? Any particular brands which
will survive better? Or is there a better tool?

I'm not too fussed if it takes quite a while and/or if the hole cutter
is worn out when finished.


There are hole cutters and hole cutters. Some are only for wood.

Yes, that's why I asked! :-)


You can get one for the job, they are not expensive. (Screwfix) It will need
to run pretty slow, a biggish drill (ideally a pillar drill or SD type
fitted with a chuck) and you need coolant on it, (water or oil ). If using
a hand drill, you can rock it as will then cut faster. Cooling is the
secret, without, it will overheat and go blunt in seconds.

As it's a boat hull I don't think a pillar drill is going to be
practical! :-) However I do have an SDS drill with a chuck accessory
so I can use that.

Lots of cooling - OK, thanks.

--
Chris Green

On Tue, 9 Aug 2011 11:49:50 +0100, wrote:

harryagain wrote:

wrote in message ...
I need to cut two 40mm diameter holes in 5mm (I think) thick steel, it
may be a little thinner.

Will an ordinary hole cutter manage this? Any particular brands which
will survive better? Or is there a better tool?

I'm not too fussed if it takes quite a while and/or if the hole cutter
is worn out when finished.

As it's a boat hull I don't think a pillar drill is going to be
practical! :-) However I do have an SDS drill with a chuck accessory
so I can use that.

Lots of cooling - OK, thanks.

Having done similar.
If the Drill is powerful enough to make the job easy it will be
strong enough to hurt you wrists if the cutter jams which it may do
just before it breaks through unless you can keep it really straight.
Be ready or use a drill with a clutch mechanism.
Should you be drilling a hull out of water from a position below your
holes remember gravity. Not many will drill such holes without eye
protection I hope but you really need something to stop swarf dropping
on hair /scalp and down your neck etc as well.
The swarf will can be surprisingly hot and sharp as well.
Thicker cutting fliuds will help by "sticking" the swarf together to
an extent.
G.Harman

wrote:
harryagain wrote:

As it's a boat hull I don't think a pillar drill is going to be
practical! :-) However I do have an SDS drill with a chuck accessory
so I can use that.

That will be handy for making oval holes.

--
Adam

ARWadsworth wrote:
wrote:
harryagain wrote:

As it's a boat hull I don't think a pillar drill is going to be
practical! :-) However I do have an SDS drill with a chuck accessory
so I can use that.

That will be handy for making oval holes.

It won't matter too much, they're just clearance holes for two small
ducts with a (supplied) stainless steel plate for the outside of the
hull that terminates them. Thus a bit of 'flap' isn't really an issue
because the stainless steel plate will cover any infelicities.

--
Chris Green

On Aug 8, 6:58*pm, wrote:
I need to cut two 40mm diameter holes in 5mm (I think) thick steel, it
may be a little thinner.

Plasma cutter. If not yours, ask where you got the steel

A decent hole saw will do it too, but it's a boring job. You _really_
want a drill press for this, not a handheld. Also a supply of
lubricant.

On Aug 9, 11:49*am, wrote:

As it's a boat hull I don't think a pillar drill is going to be
practical! :-) *

Magnetically clamped drill is the usual for in-place drilling. They're
hireable.

I'd ask a boatyard to do this. A bigger yard, handling steel hulls (or
anywhere with much work on narrowboats), will have a magnetic drill
and a plasma cutter.