I'm changing inch and a half (40mm) outside waste pipes, from old dirty white to new shiny black. When it occurred to me that it's possible that not everyone knows this simple trick for marking pipes for a square cut.
Cut a two inch wide (can be wider for bigger pipes, but too wide won't be so easy to manage on smaller pipes) piece of card (cereal pack card is ok) that has a good straight edge, which is long enough to bend around the pipe to be cut with a bit of an overlap. After making a mark where the cut needs to be, wrap the card around the pipe and line up with the mark and make sure the the card edge matches position on the overlap. Then mark the pipe.
If however you have a dark pipe, you can wrap some masking tape around the pipe, roughly central to where you need to cut. Then you can make more easily seen marks.
Now that I'm a bit practiced at this, especially with the darker pipes just wrap the masking tape around the pipes, how I suggested for the card, usually with two inch wide tape, I line it up on the second or third go. Obviously small waste pipes aren't that critical
Yeah, I can cut accurately enough without this, but I thought I'd share for those that can't.
Below is a picture where I used a small piece of masking tape to mark the pipe length allowing for saw cut, and then wrapped the masking tape with accurate overlap to use the edge of which as my sawing line.
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