Cutting Large Diameter Copper Waste Pipe
ASwissCarpenter
| Posted in Construction Techniques on
I’m remodeling a 1950’s bath where all of the DWV is plumbed with 3″ copper. I need to extend one of the arms with a Fernco to new PVC. What’s the best way to cut large copper tube without a huge tubing cutter? I’m going to assume that a long metal blade in a sawzall will do the trick, but any suggestions to keep deformation to a minimum and get a decent enough cut? Any better technique that I’m not thinking of?
Replies
You might want to use a couple worm drive clamps as guides.
match the tooth count to the job.
I just did this at a friend's home where I had to cut 3" copper to insert some new PVC for a new 3-piece bathroom. I tried using an oscillating multi-tool and a fine-tooth blade in a reciprocating saw, but it was very easy to deform the old copper and have the copper pipe develop a split. Using a grinder with a thin metal-cutting blade worked the best, with negligible deformation or splitting of the copper, and making a very clean cut.
To bolster the copper pipe, I sleeved the ends with 3" copper connectors without stops, then used the appropriate Fernco fitting to connect the PVC to the old copper. The copper connectors enabled me to properly torque the Fernco without deforming the old copper...
Since I didn't have an acetylene torch for sweating the copper connectors, I actually glued the fittings in place with a product called "Just for Copper", and it worked very well, though the product information indicates that it's for 2" diameter copper and smaller. If you try this approach, be sure to dry fit the connector, so it slips on without trouble when the "Just for Copper" is applied.
The "Just for Copper" really comes in handy for the places you can't use heat. I would also vote for a metal cutting disc in an angle grinder. You can now get a diamond cutting version for metal.