Cutting a 3" hole in cast-iron waste stack

I'm looking to cut a 3" hole into a cast iron waste stack so that I can attach a 3" PVC adapter to the waste stack in the basement. I will then attach a separate 3" PVC riser (from the 2nd floor) to the PVC adaper in the basement.
I'm wondering if anyone here has any similar cutting experience that they'd be so kind as to impart.
The best advice I have so far is to drill a series of holes on the circle that rpresents the new opening in the cast iron and then connect the holes (scroll saw, sawzall, rotary cutting tool?).
Thanks for your consideration!
Al
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Since the weight of the entire cast iron stack is resting on the pipe, I would have serious concern that opening a 3" hole in the basement could cause the stack to fracture and to collapse.

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I don't think you will have any success cutting a hole into a stack without it shattering. Your best bet is to find a spot where a T-wye can be inserted and do a proper transition to PVC.
Happy modeming, Bill
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On Mon, 19 Apr 2004 15:25:02 GMT, "berkshire bill"

Hi Bill, thanks for the response. That's a good thought about the T-wye, and I had considered that general idea earlier on and there is, in fact, a cleanout at the base of the stack (at the floor) which is about 5 feet and ~30 degrees away from the 3" PVC stubout (about 1' beneath the basement ceiling joists). I started thinking about the hole-cutting idea after a plumber in a plumbing supply suggested the PVC saddle adapter and made it sound like it was a pretty routine solution to my retrofit problem. All the books I'd looked at at the time were unanimous that I'd need to cut a section out of the riser with a chain cutter...now, THAT did scare me. ;) So, the hole cutting possibility seemed way closer to my comfort zone.
I'm going to look closer at the feasibility of the wye-solution and I'll keep you guys updated on how things work out.
Btw, I am under the impression that cast iron machines real well (I suppose that's why it's used for engine blocks), so shattering may not be a risk.
Thanks for the advice.
Al
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Sorry, Bill, it appears that I misunderstood (below) your suggestion. For some reason I thought you were suggesting adapting to an existing cleanout.
Brain fart on my part.
Al

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snipped-for-privacy@rochester.rr.com wrote:

Saddle fittings are not permitted. Also, the PVC saddle may not conform to the radius of the CI pipe.
If you *must* do it this way, consider renting a hole saw the right size. Whether you swiss cheese the hole or saw it, there is the risk of weakening the CI. That stack supports a *lot* of weight all the way to the roof. A small fracture will propagate until the section fails.
Jim
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Hi Jim, thanks for responding.

I had no idea..that's true in all states?

When I hear "hole saw", I think of an accessory that attaches to a hand drill and that's most often used to drill new wood doors to accept locksets. Is the hole saw you refer to similar to this or do you refer to a specialized tool that's dedicated to hole cutting?

There's three 3' sections of pipe stacked onto the section that I would be cutting into; the cast iron extends only to the 2nd floor floor and PVC from there to the roof. Never having lifted a 3' section of that pipe, I have little sense of how much 3 would weigh - I'm *guessing* between 2 and 3 hundred pound -- not really an enormous and unmanageable weight.
But as a precaution, I have taken much of the weight off the section where I'd be cutting. I've installed a steel 4" riser clamp to the cast iron pipe just above the cutting site and just below the CI's bell-type flare and attached a length of chain from each riser clamp bolt to ceiling joists on either side of the CI riser. I snugged the chain with a turnbuckle on either side. The weakest link at each side is rated at 300 lbs.
I'm nevertheless seriously considering Bill's wye-solution.
I'll keep you guys up to date.
Thanks again.
Al
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That's basically the right tool, however, the ones they're referring to are much beefier than the cheapies sold with lockset kits. Usually carbide tips etc.
You will need a _big_ 1/2" drill to do this. And very strong arms.
For a friend, I drilled a 2 1/2" hole in some well casing to install a pitless adapter.
It was an industrial rated hole saw attachment on a heavy duty 1/2" drill (one of those really old 600RPM monstrosities with "jack hammer"-like handles).
Little risk of shattering the pipe (it's steel, not cast iron), but, I broke about four 1/4" pilot bits [+] and knocked off a couple of carbide teeth. I came close to losing a few teeth of my own.
Install a proper Tee like everyone else suggests is the right approach. You won't be happy with the saddle connection. Even if it were legal.
Saddle connectors suck. They ALWAYS leak.
[+] Today's helpful hint: in thick metal (especially pipe), predrill the pilot hole for a hole saw. Then, substitute in a suitably sized hex screwdriver bit into the hole saw, and use _that_ to guide the hole saw. Standard hex screwdriver bits are _vastly_ better able to stand up to chatter than a 1/4" drill bit. How did I learn this? By running out of 1/4" drill bits and being a bit desperate...
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
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Thanks for the advice, Chris, you've pretty much persuaded me to abandon the saddle idea. See embedded comments below.

This is decisive for me. If the installation of a PVC saddle likely will have an iffy result, there's hardly much point in putting myself thru the apparently arduous and problematic installation proccess.
And its illegal to boot.
I'm quite happy I talked with you guys before I dove in.

Good tip!

I put the above phrase (latin?) into Google and it returned a bunch of articles written by yourself in different forums - not very helpful. Would you translate?

I guess I'm not sufficiently up on Star Trek trivia. What's the name of the SC class you refer to here? The "Lewis"?
Thanks again, Chris.
Al
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We all have to have our own little mysteries ;-)
Tho, I'm told it's lousy latin.


http://ravenstarstudios.com/components/clewis.html http://artships.com/spamfighters.php
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.
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Cut out a short section of the CI pipe and install a proper tee. Make sure the upper section is supported before cutting.
--

Larry Wasserman Baltimore, Maryland
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Al
I read the entire thread before responding
Your best and easiest path to success is get a group of Torch Blades (trademark of Milwaukee) and a Sawzall.
The Torch Blades cut cast iron like it was just steel. It may two or three blades to do both cuts. I could do it with one but I have been using a sawzall for 30 plus years.
You have indicated that you have the upper portion of the stack supported.
I dont recall if the stack is 3 or 4" but get the correct Wye either 3 x 3 or 4 x 3 and add at least 6 " of PVC to both of the runs of the Wye and add about 1/4" to the total developed length and make your two cuts.
While you are at home cheapo or wherever you shop for plumbing stuff pick up two Fernco's for the stack diameter. Not No-Hub. Not some other cheap junk...Make sure the name Fernco is on the rubber sleeve.
A Fernco is a Rubber Sleeve that will fit over your cast iron (take note of whether on not your cast iron is XH or not).
You have now assembled your PVC Wye with a 6" piece of Sch 40 PVC glued into each run of the Wye.
You have sucessfully cut out the proper length of cast iron leaving at least 3" of cast iron sticking out of any fitting so you can slide the fernco over the cast iron.
You now drive back to the hardware store and get the cast iron soap I forgot above. Cast Iron soap is a very slimey substance that allows rubber to slide over PVC and cast iron.
Liquid dish detergent works in a pinch
Open the stainless steel clamps on the fernco's ...not completely leave the last little bit of the slotted band engaged in the screw portion of the band.
soap the inside of the fernco with the slimey cast iron soap... get the entire insides of the fernco semi soapy...apply some soap to the outside of the PVC pieces sticking out of the runs of your Wye.
Slide the Fernco over both ends of your PVC assembly until the ends of the ferncos are about 1/2" past the ends of the PVC. You want about 1/2" of white plastic sticking out of both ends of your PVC assembly
Soap enough of the cast iron to accept 1/2 of the length of the Fenco plus about 1" longer for slop.
Install the PVC assembly in the opening in your cast iron stack...now it gets to be fun slide the lower Fernco over the cast iron and tighten the lower band only...not bulls ass tight just yet...then holding down on your PVC assembly raise the upper fernco and tighten (see above bout the bull).
Now we have to line up the Wye with your new stack ...since I am not there I cannot advise you step by step...but you will need a 3" PVC Street 45 to plumb the outlet of the Wye.
Once you have the new stack plumb*; it is time to tighten the bottom band. Now we very slowly allow the upper fernco to accept the weight of your existing soil stack.
tighten the uppper fernco upper band when the weight has been accepted
double check plumb on the new stack and tighten inner fernco bands.
that is the proper and code accepted way in just about any place in the US where PVC is accepted as a listed material
Damn I'm tired just typing about it :)
Vic Plank Lancaster PA
snipped-for-privacy@comcast.net
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On 19 Apr 2004 19:36:48 GMT, snipped-for-privacy@aol.com (POPPYPLANK) wrote:
Hi Vic. Thanks for the detailed answer, I very much appreciate it and it's looking at this point that it will be the roadmap I will be following.

Do you recommend against a snap cutter?

Yes, a double chain, turnbuckle arrangement attached to ceiling joists at one end and the riser clamp (gripping the 4" cast iron riser) on the other. However, this arrangement was only intended to relieve the load at the site on the cast iron I had originally intended to cut a 3" hole. I'm not sure I would trust this arrangement to both bear the full weight of the riser and offer sufficient lateral stability to the riser while removing a whole section of it.
What do you consider sufficient support? Do you build a, say, 2x4 framework that supports a riser clamp (clamped to the CI riser) from the floor?

4"
I'm thinking the correct Wye is a "waste T". The leg that will receive the PVC opens perpendicular to the legs that will receive the cast iron, but a downward sweep is molded into the this perpendicular leg. Are we thinking of the same fitting?

Ok. So the length of the cut will be the total length of the PVC assembly plus 1/4".

I will make sure I get Fernco .

I don't know how to distinguish XH from whatever else (SV?) there is. I ground off much of what's embossed on the exposed riser because, as indicated earlier in this thread, I had originally planned to install a PVC saddle T with gasket and I wanted to insure a good seal. But it seems that XH would have a larger OD than the SV.
I guess I'll just have to measure the riser diameter and compare it to the available Ferncos.

Ok.

Damn! I knew I forgot something!

Ok.
Ok.
Ok.
Ok. If I'm reading you right, you're saying that the Ferncos are to be pulled all the way down over the PVC at each end till about 1/2" of PVC is left exposed at the ends.

Ok,
Ok.
I'm not sure I understand what you're telling me, here. Are you saying that I should temporarily install the Street 45 into the Wye outlet so that I can get a fix on how plumb the assembly is, and adjust accordingly? If this's right, I should probably stick a 2' or so length of PVC into the other end of the 45 to put a level up against.

I'm not clear how that's done. You seem to be implying that the support that's initially erected for the CI riser is constructed such that it can be gradually diminished, allowing the riser to actually move down about 1/4". How do you usually accomplish this?

Ok. But I hope you will further comment on how I might accomplish letting the CI riser settle onto the Wye. I take it that the PVC Wye can bear the weight of the riser column.
Has it ever happened to you that that 1/4" of riser movement has translated into consequent problems above..like, for example, a roof leak?

Ok.
Thanks for the detailed proceedure, Vic, much appreciate it. It's looking like this is what I'm going to be doing.
Al
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That depends on the condition of the cast iron you are cutting. I know the combo of Sawzall and Torch Blades will work in every instance. If you try to use a snap cutter and it crushes the old pipe you are in a world of bad things...took me about 12 hours one time when I crushed the cast the snap cutter and I know how to use the snap cutter.

It seems that you have the weight supported...just kinda rig something so you get no left-right or front-back movement of the existing stack (which I am assuming is a vertical stack)

Negative. You are referring to a Sanitary Tee...bad idea...get a wye where the branch is at a 45 degree angle to the run of the pipe. Much better flow for solids and paper and whatever else gets put in the toilet.

Look on the Hubs of the pipe and fittings if it has an XH cast into the hub it is XH ..depending on the age it may or may not have SV ( Service Weight) cast on the hubs.

Thats right Pilgrim :)

I Knew this was gonna be a problem...see above about use of Wye vs. San Tee.
The street 45 will bring your connection from a 45 offset to a vertical riser again...since I dont know where your new PVC riser is in relation to existing cast iron riser...I just wanted to make sure that the new wye with street 45 installed was plumb and level.
Heres a trick get a torpedo level and lay it the wrong way across the top of the street 45 and when all three bubbles are in the lines the fitting is level and plumb in most of the 3 dimensions...just make sure you are on the flat of the torpedo level.

Nah...the 1/4" is just a fudge factor..just allow the existing cast iron stack just to lower slowly...if you have riser clamps just loosen the bolts evenly (side by each) and when you feel the tension on the bolts start to relax...just wait a minute or two and loosen just a bit and wait and repeat process. ( this is a great time to have a malt beverage refreshment) :)

Negative see above

Al: My email is snipped-for-privacy@comcast.net...if you can take some digital pictures of exactly what you are doing ...I can offer more consice advice.
Sorry bout the delay in replying ..I became a grandpoppy twice yesterday....
do you want to hear about my grandbabies?
Vic Plank Lancaster PA

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On 21 Apr 2004 21:17:15 GMT, snipped-for-privacy@aol.com (POPPYPLANK) wrote:
Thanks for the clarifications, Vic.

The CI appears to be in excellent shape, the house was built in 1949. Of course, that applies only to the pipe's exterior, I have no idea what's happening on the inside.

Ok. Yes, the stack is vertical.

Ok. Glad to hear that as it verifies my intuition. For some reason, books on the subject I've seen give the impression that a Sanitary Tee is the preferred fitting and I've wondered why a 45 wouldn't be better.

Ok. I was looking at the Fernco couplings at Home Cheapo and they seem to specify use is ok through a range of weights including both XH and SV, so it appears not to be an issue anyway.

We're on the same page because I had a Wye in mind anyway (I cleverly forgot about the Sanitary T when thinking about your level/plumb instruction).

Ok, I understand.

That's an interesting tip!

Ok. Nothing elaborate, just a little time and patience.

Thanks, Vic, you're more than generous with your time and knowledge. I'm confident I now have the necessary information and related understanding to proceed.

Congratulations, grandpa! :)

Sure, shoot.
My email is: snipped-for-privacy@rochester.rr.com
Thanks again, Vic, I'll let you know how things work out.
Al
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