Shortening a 2″ cast iron drain pipe
BuckeyeBeaver
| Posted in Construction Techniques on
We’re replacing a basement shower with a new, tiled shower. I need to shorten the 2″ cast iron pipe coming out of the ground. (See photo). I have a Fernco I can use to add on a piece of ABS which will connect to the new drain, but if I put it on with the pipe as it currently exists, the drain assembly sits several inches too high. Is there some way to cut this pipe cleanly without diging up the floor?
Replies
The ideal tool is a chain cutter, but you first have to buy/borrow/rent one, and then somehow get it on there, given that the pipe is recessed in that hole.
Otherwise you could attempt to notch it all around with an appropriate grinder bit on a die cutter or Dremel.
Shortening a 2" cast iron drain pipe
Yeah. A chain cutter is what I know about, but I'd need to open up the floor to fit it in. I used a diamond grit sawzall blade to cut through the old shower drain parts when I demoed the old shower, so I could use that, too, but still would have to dig up the floor.
Thanks for the replay.
See if you can rent an internal pipe cutter. Be sure to get one suitable for cast iron and not just plastic.
Shortening a 2" cast iron drain pipe
That sounds like what I need.
On Monday I'll call around to some tool rental places and see if any of them have one.
Another idea was to get a diamond grit wheel for a Dremel tool. The thought was to do it on the outside. But I do have a dremel chuck on a flexible shaft that would fit inside the pipe. It would probably take a long time to do it, but it might work. Hopefully I'll find an internal pipe cutter for cast iron at a rental place.
Thanks for the replay.
Air tool attachments.
Be sure to check out attachments for small air tools. I think you'll find many more designed specifically for metal cutting.
Chip out a little bigger hole and get in there with a side grinder. You are fixing the floor anyway, An extra cubic foot of concrete is trivial.
You do have the problem that that pipe is going to be brittle and apt to crack in ways that would not be appreciated. Be prepared for the possibility that you may need to dig all the way down and replace a section.
Hard for me to gauge from the photo how much below the top of the slab you need to go and access.
Without renting a tool or buying an interior cutoff disc, an angle grinder with an abrasive disc would be my choice. I'd score around the outside if I could, making a few go-arounds as needed, going deeper each time.
I'd possibly make relief cuts from the top down if that would help. Straight or angled to nibble away what needs to be nibbled.
4" angle grinder, straight
4" angle grinder, straight down with longitudinal cuts 6 places, then just tap the 'fingers' witha hammers and you are set to go.
Or, if you are good with a hammer and cold chisel, just chip it away. Air hammer with straight blade and peel it down to where you need.
Get a long nose electric die grinder and a 1 1/2 inch cutting disk. Stick it inside the pipe and cut away.
Harbor freight sells a die grinder for $50.00
Thanks for all the comments, suggestions, and warnings. I happened upon a retired plumber at my local Home Depot who has successfully used Dremel disks. He says i should expect to use up a 5 pack of carbide disks. I have an old Dremel scroll saw with a power take off, flexible shaft accessory that will fit inside the 2" pipe. I'll be giving this a try on the weekend and will post pictures and my experience afterwards.
Thanks again for all the helpful comments.
Another thing that would work is a plasma cutter. They are probably not available for rental, but if you know anyone who restores cars, or welds, they may do the job for you. It's incredibly fast to cut with one, and the cut is clean.
Even an oxygen +fuel (acetylene, propane, mapp, natural gas) cutting torch would work well.
I'm surprised no one has suggested a shaped charge.
Resolved: Shortening a 2" cast iron drain pipe
Success!
Our first try was with an old Dremel scroll saw with a power take off for a flexible shaft. The tool was from the late '60s. It was something my dad used to carve some chess pieces. By now it no longer has enough power to keep the cut off wheel turning once it hit the pipe. So, off to the Big Box store, the one where Homer works, to get a new Dremel 4000 and a flexible shaft for it. Nice case. Even has a place in it for the flexible shaft.
First we dug out the hole so there'd be room for the Fernco. Losening the sand and gravel was pretty easy. The tool that worked to get it out of the hole was the ShopVac.
Next I marked the Dremel flexible shaft with blue tape to show me the depth of cut. I used four out of the package of five cut off disks. Unfortunately I did not have a way to maintain a horizontal cut, so by the time I got around to where I started I was off by about 1/4". I put an iron bar against the outside of the pipe, and put a crow bar inside the pipe and gave a gentle tug. The pipe snapped off nice as you please, and didn't damage what was below the cut.
One of the concerns raised by one of you was keeping chunks of cast iron out of the drain. All that went down there was what was ground. It was a nice, smooth cut with not chunks broken off.
Then I put a short piece of 2" ABS in the Fernco and snugged up the hose clamp. I pushed the Fernco over the cast iron pipe and adjusted the hight of the ABS to be 2-5/8" below the concrete floor. This is the position needed for the Durock Shower System.
I had to dig out a bit for my 1/4" socket drive to fit, but I was able to use it to tighten the Fernco to the cast iron pipe
Before we cover it up we'll pour some sand around the pipe. It wiggles a bit right now, and it didn't do that before we dug down this morning.
On with the rest of the project.
Thanks for all the encouragement and tips.
Thanks to you, too.
Too often we never learn the out come of our advice. It's satisfying when we do.
Thanks for coming abck to tell us what you did.