cast iron pipe & hole saw

[Daljit]

Hi

Can anyone advise what kind of hole saw i would use to drill into a cast iron waste pipe? Where to buy? I'm thinking of drilling a hole to fit a bath waste pipe which is about 42mm wide.

thanks

Daljit

[Great Scot]

If I were undertaking such a task I would use a mag drill with a good cutter . Another option might be a (good) Starret hole saw with appropriate pilot and arbor. GS

[John Stumbles]

I've drilled smaller holes (about 25mm) in a cast-iron bath with a standard bimetal hole saw from screwfix or the likes. It was hard work!

[Jim Michaels]

Bimetal hole saw, lots of lubricant, steady grip, slow speed, spare pilot bits, and a lot of time.

Improvements from experience; clamp a wood block (cut curve in backside) to pipe and once through the wood remove the pilot bit and increase speed. When almost fully cut, stop drilling, place a wire into pilot hole to hold coupon and pry coupon to break last bit on each side. Plan on getting about one hole per saw.

FYI Coupon is the American technical term for the remnant from a hole saw and often an inspector will want to see it to verify a proper hole was made.

SPAMX from email address

[Roger R]

Perhaps we had better have an English term for use over here. How about Receipt?

Roger R

[Stuart Noble]

Might be easier to replace the cast iron section with plastic

[Phil L]

We already have one, it's 'cutout'

[Ed Sirett]

I've done this a couple of times. There are two approaches:

1) (by the book method). Cut out a section of the soil stack and replace the section with plastic. Get two rubber couplings and put a section of 110m plastic in the gap. You then hole saw the side of the plastic and add a strap on or solvent weld boss. 63mm is the size you'll need IIRC.

2) Use a grit edged hole saw again 63mm IIRC and add strap on boss. You'll need to pack out the strap as the CI soil stack is a bit less than 110m. You'll need to seal the boss to the CI plumber mait or silicone should do.

[Dave Plowman (News)]

I'd be slightly worried about the weight of the stack above sitting on this - and the disruption you might cause to the fixings by cutting the stack.

I prefer the sound of this.

[David Hansen]

On Tue, 16 Jan 2007 22:41:12 +0000 (UTC) someone who may be Ed Sirett wrote this:-

That is roughly what I did two decades ago in one of the houses I keep an eye on. The right sort of boss has a short projection so that the water stream will not touch the cast iron for some way down.

Still sound two decades later and likely to remain that way for a very long time. Far better in all respects than removing a section of cast iron pipe and replacing it with plastic.

[pjlusenet]

When I was younger and slightly more ignorant than I am now I used several HSS drill bits to make a circle of holes in the pipe. I got them as close together as possible and then knocked the centre through with a hammer. Of course when I mentioned this to a friend 'in the trade' he was horrified and said I was lucky I didnt shatter or crack the stack!

(so it sounds like you're smarter than me)

[Stuart Noble]

I think the idea is to replace a whole section of the cast iron so there's no cutting involved.

[Dave Plowman (News)]

Could then be a *very* costly option given there's usually a vent to each stack.

[Ed Sirett]

On the few occasions I've done this I've mostly gone for the grit edged hole saw.

A couple of times I went for the replace the upper half of the soil stack with plastic which has the advantage that you only need one of the expensive rubber couplings.

>

[Daljit]

Just to say thanks for all advice given.

Daljit

[bobs]

what is a mag drill. I was thinking of buying a 1/2" impact driver

[newshound]

Magnetic drill. Google it.

For sure I would not be using an impact driver on cast iron pipe.