The fitting in the last picture is not threaded on the bottom, but it is a very tight fit. The plastic PVC coupling slips over the outside of the riser. If it doesn't hold then I'll have to rethink that part. The riser pipe is cast iron, I believe, or something like that. Actually, I assembled it on the workbench in the garage, but brought it inside for the pictures to get better lighting. But, once that puppy has been used you can believe Elaine will never allow it to pass over the threshold of our home again....
